Fundamentals of Materials Chemistry 9781774694343

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The Fundamentals of Materials Chemistry

THE FUNDAMENTALS OF MATERIALS CHEMISTRY

Edited by: Saeed Farrokhpay

ARCLER P

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e

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www.arclerpress.com

The Fundamentals of Materials Chemistry Saeed Farrokhpay

Arcler Press 224 Shoreacres Road Burlington, ON L7L 2H2 Canada www.arclerpress.com Email: [email protected]

e-book Edition 2023 ISBN: 978-1-77469-681-1 (e-book)

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ABOUT THE EDITOR

Dr Saeed Farrokhpay is a Chemical Engineer with several years of experience in mineral & material processing. He obtained his PhD from University of South Australia in 2005. He is currently a Technical Consultant in Australia. He has worked for more than 20 years at mineral and chemical industries, universities and research centers around the world. Dr Farrokhpay has published more than 90 papers in high ranked journals and conference proceedings. He has also edited several technical and scientific books, and served as an editorial board member of several international scientific journals.

TABLE OF CONTENTS

List of Figures ........................................................................................................xi List of Tables ...................................................................................................... xvii List of Abbreviations ........................................................................................... xix Preface........................................................................ ................................... ....xxi Chapter 1

Introduction to Materials Chemistry ......................................................... 1 1.1. Introduction ........................................................................................ 2 1.2. History of Materials Chemistry ............................................................ 3 1.3. Factors in the Design of New Materials ............................................... 8 1.4. Design of New Materials Through A “Critical Thinking” Method ......... 9 References ............................................................................................... 14

Chapter 2

Solid-State Chemistry .............................................................................. 19 2.1. Introduction ...................................................................................... 20 2.2. Amorphous Vs. Crystalline Solids ...................................................... 20 2.3. Types of Bonding In Solids ................................................................ 22 2.4. The Crystalline State.......................................................................... 30 2.5. The Amorphous State ........................................................................ 33 References ............................................................................................... 47

Chapter 3

Chemistry of Semiconducting Materials .................................................. 57 3.1. Introduction ...................................................................................... 58 3.2. Characteristics and Kinds of Semiconductors .................................... 58 3.3. Semiconducting Nanowires .............................................................. 65 3.4. Silicon-Dependent Uses ................................................................... 67 3.5. Thermoelectric (TE) Materials ............................................................ 68 3.6. Important Materials Uses: Photovoltaic (Solar) Cells ......................... 74 References ............................................................................................... 80

Chapter 4

Fundamentals of Polymeric Materials ..................................................... 87 4.1. Introduction ...................................................................................... 88 4.2. The History of the Concept of the Macromolecule ............................ 89 4.3. Classification of Polymers ................................................................. 91 4.4. Structure and Properties of Polymers ................................................. 93 4.5. Thermoplastic Polymers .................................................................... 93 4.6. Thermosetting Polymers .................................................................. 101 4.7. Naturally Occurring Polymers......................................................... 108 References ............................................................................................. 113

Chapter 5

Introduction to Carbon Materials.......................................................... 121 5.1. Introduction .................................................................................... 122 5.2. The Graphite Family........................................................................ 126 5.3. The Diamond Class ......................................................................... 130 5.4. The Fullerene Family ....................................................................... 136 References ............................................................................................. 137

Chapter 6

Chemistry of Nanomaterials .................................................................. 141 6.1. Introduction .................................................................................... 142 6.2. Fundamentals of Nanomaterials...................................................... 145 6.3. Characteristics of Nanoparticles (NPS) ............................................ 148 6.4. Classification of Nanomaterials....................................................... 155 6.5. Properties of Nanomaterials ............................................................ 157 6.6. Nanomaterial Processing and Synthesis .......................................... 163 6.7. Accumulation and Uniformity of Nanoparticles (NPS) .................... 176 6.8. Characterization of Nanoparticles (NPS) ......................................... 178 6.9. Application of Nanomaterials ......................................................... 180 References ............................................................................................. 186

Chapter 7

Introduction to Composite Materials .................................................... 199 7.1. Introduction .................................................................................... 200 7.2. Fiber Reinforced Plastics (FRPS) ...................................................... 203 7.3. Science of Composite Materials ...................................................... 204 7.4. Orthotropic, Isotropic, and Anisotropic Materials............................ 208 7.5. Rule of Mixtures and Curing of Composites .................................... 210 7.6. Composites Versus Metallic Materials ............................................. 212 viii

7.7. Drawbacks and Advantages of Composite Materials ....................... 214 7.8. Fabrication Process for Composite Materials ................................... 215 References ............................................................................................. 227 Chapter 8

Characterization Techniques for Different Materials ............................ 235 8.1. Introduction .................................................................................... 236 8.2. Electromagnetic Spectroscopy ........................................................ 236 8.3. Nuclear Magnetic Resonance (NMR) Spectroscopy ........................ 240 8.4. Light Scattering Techniques ............................................................. 247 8.5. Electron Microscopy ....................................................................... 248 8.6. Scanning Probe Microscopy (SPM) ................................................. 252 8.7. X-Ray Diffraction (XRD) .................................................................. 253 References ............................................................................................. 257 Index ..................................................................................................... 263

ix

LIST OF FIGURES

Figure 1.1. Schema of classification for the numerous sorts of building materials Figure 1.2. Schedule of significant development endeavors in the field of materials science and engineering Figure 1.3. Using the manipulation of Co atoms on a Cu(111) surface, we were able to create a 40-nm wide logo for the NIST. Similar to how ripples appear in a pond when stones are put in, the ripples in the background are caused by electrons in the fluid-like layer at the copper surface jumping off cobalt atoms, creating the shapes seen there Figure 1.4. Illustrations for the “top-down” and “bottom-up” approach to materials synthesis Figure 1.5. For the design of a novel material, here is an example of a critical thinking strategy Figure 2.1. Ionic model for sodium chloride Figure 2.2. An extended metal network with d-orbital overlap between neighboring metal atoms Figure 2.3. A band figure for titanium metal that shows the continuity between the valence band and conduction band (i.e., no bandgap) Figure 2.4. Instances of h-bonding in (a) water/ice; and (b) the HF2 ion in liquid hydrogen fluoride are shown Figure 2.5. Diagram illustrating three frequently used ways for growing single crystals Figure 2.6. There are models of the 14 Bravais lattices. The various types of Bravais centering are indicated by the symbols P (primitive/simple), F (face-centered), I (bodycentered), and C (complex/complex) (base-centered). The basic rhombohedral Bravais lattice, abbreviated R, is a trigonal symmetry primitive unit cell Figure 2.7. Core structure comparison of (a) siloxy-substituted alumoxane gels with (b) diaspore; and (c) boehmite minerals. The atoms of oxygen and aluminum are depicted in red and blue, correspondingly Figure 2.8. Illustration of the products obtained through sol–gel processing Figure 2.9. Unit cell of the α-quartz crystal lattice Figure 2.10. An optical fiber in cross-section. The transmission of visible light thru a step-index multimode fiber (a); a graded-index multimode fiber (b); and a single-mode fiber (c) is shown

Figure 2.11. Cross-section schematic of an (a) electrochromic device; and (b) suspended-particle device Figure 2.12. A powdered cement grain is seen in the cross-section. Tricalcium silicate (Ca3SiO5), tricalcium aluminate (Ca3Al2O6), and tetracalcium aluminoferrite (Ca2SiO4) Figure 3.1. Silicon electronic band representations. (a) Bands arising from sp3 hybrid orbital overlapping; and (b) bands coming from molecular orbital overlapping are shown Figure 3.2. The extrinsic and intrinsic semiconductor band representations. (a) An intrinsic semiconductor with an equal amount of free holes and electrons; (b) an n-type extrinsic semiconductor with a larger amount of electrons; and (c) a p-type extrinsic semiconductor with a larger amount of holes can be seen Figure 3.3. The formation or movement of holes and electrons caused by siliconsilicon bond thermolysis is seen in this diagram. The movement of an electron from a neighboring shell to fill the vacancies is shown in (a) the discharge of an electron and the development of a hole; and (b) the discharge of an electron from a shell to fill the vacancies Figure 3.4. Replication of electron-hole pairs generates whether it is photon energy or heat, as seen in this diagram Figure 3.5. Relationship of (a) direct energy bandgap (such as GaAs); and (b) indirect energy bandgap (such as silicon, germanium) materials Figure 3.6. Resistivity to temperature comparison for (a) metals; and (b) semiconductors Figure 3.7. Harvesting triplets are seen in this diagram. The triplet excitation energy is transformed to heat in the absence of a triplet emitter, resulting in a loss of 75% of the efficiency of quantum. Several organometallic compounds are also depicted, along with their respective spin-orbit pairing values, which are directly related to their application in luminescent OLEDs Figure 3.8. Schematical representation of a thermoelectric gadget that can be used for generating power or cooling Figure 3.9. Bi2Te3 unit cell – a well-studied TE material. Bismuth atoms are blue, whereas tellurium atoms are pink Figure 3.10. The lattice of an empty IrSb3 skutterudite. Antimony atoms are revealed in black (top); and Type I/Type II clathrates (bottom). Figure 3.11. Crystalline structure diagram of CoO2-dependent thermoelectric oxides publicized are (a) NaxCoO2; (b) Ca3Co4O9; and (c) Bi2Sr2Co2Oy Figure 3.12. The temperature base of ZT values for different thermoelectric materials. TAGS mentions to (GeTe)0.85(AgSbTe2)0.35 Figure 3.13. Representation of (a) a single-junction; and (b) multijunction photovoltaic cell Figure 3.14. Diagram of a dye-based photovoltaic cell. The TiO2-bound dye molecules perform as the light harvester xii

Figure 3.15. The backward or forward electron transfer between the TiO2 surface and the activator is described in depth in this diagram. The sensitizer ligand has a carboxylate group, which is required for Lewis base–acid-binding to the oxide surface. A holetrapping group, as represented in (b), prohibits back contribution from the TiO2 surface to the activator (enhancing the photocurrent created via the dye-sensitized solar cells) Figure 4.1. Polymer categorization Figure 4.2. Various kinds of macromolecules Figure 4.3. Comprehensive categorization of polymers Figure 4.4. The structural formula of polythene Figure 4.5. Polypropylene’s structural formula Figure 4.6. PMMA polymer’s structural formula Figure 4.7. Structure of vinyl benzene (styrene) Figure 4.8. PVC’s structural formula Figure 4.9. Epoxy’s structural formula Figure 4.10. The fragment of the phenol-formaldehyde polymer Figure 4.11. Structures of melamine and urea Figure 4.12. The structure of polytetrafluoroethylene Figure 4.13. Cellulose’s structural formula Figure 4.14. The structural formula of starch Figure 4.15. Structures of protein: (a) primary structure; (b) secondary structure; (c) tertiary structure; (d) quaternary structure Figure 5.1. There are three carbon allotropes which are: (a) graphite, with the two hues illustrating the A and B layers in the AB stacking pattern; (b) diamond; (c) fullerene. There are pentagons and hexagons to be found Figure 5.2. The crystalline structure of HCP Figure 5.3. Measured phase diagram of C, showing the optimum stages for a variety of pairings of pressure (on the vertical axis) and temperature (on the horizontal axis) Figure 5.4. The comparison of the structures of C60 and C70 molecules. The additional 10 C atoms are indicated by the red balls in C70 Figure 5.5. Carbon-carbon composites are used to make rocket nozzles Figure 5.6. A diamond-coated metal instrument Figure 5.7. A diamond-coated elliptical stoneware fiber Figure 5.8. PECVD (plasma-enhanced chemical vapor deposition) is used to cover a diamond using carbon-containing gas as the carbon source Figure 5.9. After annealing, chemical vapor extraction single-crystalline diamond sheets with various hues and sizes ranging from one half to two carats were obtained

xiii

Figure 5.10. To transfer the heat generated by the chip, a chemical vapor deposition diamond heat spreader sheet is used between the heat sink and the semiconductor chip Figure 5.11. (a) DLC (diamond-like carbon), diamond, and other materials’ toughness (Vickers scale); (b) DLC as well as other materials’ coefficients of friction Figure 5.12. DLC is applied to a metal cutting instrument Figure 5.13. The structure of graphene. The C atoms appear black, whereas the H atoms are gray Figure 5.14. An instance of C60 that has been functionalized Figure 6.1. Evolution of technology and science and the future Figure 6.2. Nanomaterial (e.g., carbon nanotube) Figure 6.3. SEM images showing (a) Ti NPs film having 80 nm thickness; (b) an Au film that is near-percolating; (c) Cu NPs that are monodispersed; and (d) Fe nanorods Figure 6.4. TEM images of NPs (examples) with different compositions and morphologies. (a) Cu NPs that are monodispersed; (b) Fe nanorods; (c) core-shell Cu–Si NPs; (d) porous Fe3O4 NPs; (e) Ni NPs decorated Fe3O4 cubes; (f) porous silica spheres on whose surface γ-Fe2O3 NPs are adsorbed; and (g) porous silica spheres embedded γ-Fe2O3 NPs. For more details regarding the characterization and preparation of these composites Figure 6.5. Binary NP’s schematic images: a mixed structure (a); a core-shell structure (b); and a layered structure; (c) of both elements A and B Figure 6.6. Ternary NP’s schematic images formed of A, B, and C elements: (a) a multicore–shell morphology (a dumbbell-like morphology is presented by cores); (b) a core–multishell morphology; and (c) an alloyed core-shell morphology Figure 6.7. (a) A Cu@Ag core-shell NP; (b) a Cu@Si multicore–shell NP; (c) a Fe@ Fe2O3 core-shell NP; (d) a CuAg mixed NP; (e) a Si NP inoculated with Ag NPs resulting in a satellite morphology; and (f) a FeAg dumbbell-like NP where the crystalline hemisphere corresponds to Ag Figure 6.8. Nanomaterial’s classification: (a) 0D clusters and spheres; (b) 1D nanofibers, nanorods, and nanowires; (c) 2D nanofilms, networks, and nanoplates; (d) 3D nanomaterials Figure 6.9. Examples of nanomaterials Figure 6.10. Emission of fluorescence (CdSe) ZnS quantum dots of different spectra and sizes of absorption of different shapes and sizes of gold nanoparticles Figure 6.11. Electrical performance of nanotubes Figure 6.12. Nanostructured material’s magnetic properties Figure 6.13. Schematic illustration of the nanoparticle’s preparative methods Figure 6.14. Schematic representation of the mechanical milling principle Figure 6.15. Schematic representation of the synthesis of the sol–gel process of nanomaterials xiv

Figure 6.16. Schematic representation of the gas-phase process of synthesis of singlephase nanomaterials from a heated crucible Figure 6.17. Ultrasonic spray pyrolysis assisted by flame Figure 6.18. Graphic representation of set-up used for nanomaterials gas condensation synthesis followed by collection in solvent media or consolidation in a mechanical press Figure 6.19. A schematic of a CVC reactor Figure 6.20. Schematic of (1) nanoparticle; and (2) particulate film formation Figure 6.21. (a) A representation of the stabilization process employed to γ-Fe2O3 NPs through the means of SDS surfactant; (b) a TEM image of the Fe2O3 NPs (precipitated) without SDS; (c) SDS-modified Fe2O3 NPs TEM image Figure 6.22. (a) A schematic representation of the exfoliation method of the NPs. Step 1: On a spin-coated PVP film, multicore–shell NPs were deposited on a glass substrate. Step 2: the glass/NP/PVP samples were immersed in methanol and then for 15 minutes it was sonicated and then separated for removing excess PVP. Step 3: The precipitated NPs are washed with methanol, and then they were resuspended in ultrapure water. (b) A histogram showing dynamic light scattering that depicts the size distribution of the HNPs Figure 6.23. The transmission electron microscope utilized to characterize the NPs Figure 6.24. The XPS system utilized for analyzing the NPs Figure 6.25. Schematic of microbial fuel cell Figure 6.26. Silicon nanowires in transistors (junctionless) Figure 7.1. CFRP (carbon fiber reinforced plastic) and GFRP (glass fiber reinforced plastic) composites for their particular strength and stiffness Figure 7.2. Typical reinforcement types Figure 7.3. Type and quantity of reinforcement have an impact on composite performance Figure 7.4. Isotropic material under stress conditions Figure 7.5. Anisotropic material under stress conditions Figure 7.6. Epoxy composite and aluminum alloy through-thickness strength comparison Figure 7.7. Fatigue characteristics of epoxy composites and aluminum alloys are compared Figure 7.8. Structural efficiency of different materials Figure 7.9. Major polymer matrix composite fabrication processes Figure 7.10. Schematic of the injection molding process Figure 7.11. Schematic of resin transfer molding Figure 7.12. Certain composites are made with laminates, which have bonded layers

xv

Figure 7.13. Schematic of compression molding process Figure 7.14. Schematic of hand-layup method Figure 7.15. Schematic of spray-up process Figure 7.16. Schematic of filament winding process Figure 7.17. Schematic of pultrusion procedure Figure 7.18. Automated fiber placement setup for composite manufacturing Figure 8.1. Block illustration of a spectrophotometer Figure 8.2. The absorption of a photon is accompanied by probable physical procedures Figure 8.3. Schematic representation of an NMR spectroscopy setup Figure 8.4. Proton NMR spectrum of CHCl3 Figure 8.5. Top: A biosensor molecule is arranged in such a way that it can bind xenon to a protein with great specificity and affinity. The cage-tying xenon and a biotin ligand are coupled by a binding molecule on each end Figure 8.6. Electronic orbits display the discharge of a photoelectron after the assimilation of a photon Figure 8.7. The auger and photoelectric procedures in (a) AES; and (b) XPS Figure 8.8. O 1s core-level XPS spectra of the In2O3 thin films at diverse circumstances: (1) After heating for one h at 700°C in the air; (2) contact with NO2 1 × 102 Pa 200°C ½ h; (3) vacuum 1 × 10–4 Pa at 200°C for ½ h; (4) contact with O2 1 × 104 Pa at 200°C for ½ h Figure 8.9. X-ray photoelectron spectra emphasizing the Se 3d core transitions from ~40 Å plain and ZnS overcoated CdSe dots: (a) bare CdSe; (b) 0.65 monolayers; (c) 1.3 monolayers; and (d) 2.6 monolayers of ZnS. The peak at 59 eV specifies the formation of selenium oxide upon contact with air when surface selenium atoms are unprotected Figure 8.10. Schematic representation of an SEM setup Figure 8.11. Schematic illustration of a TEM setup Figure 8.12. Diagram of the fundamental concept behind scanning probe processes Figure 8.13. Condition for constructive interference Figure 8.14. The correlating simulated designs (dotted line) for distinct particle sizes and experimental XRD designs of ZnO nanocrystals Figure 8.15. Powder XRD spectra of a sequence of InAs nanocrystal sizes on the left. The crystalline area size might be determined by measuring the breadth of the reflections—powder X-ray diffraction showing a sequence of InP nanocrystal sizes on the right. The bottom shove spectrum depicts the mass reflection position with relative intensities

xvi

LIST OF TABLES

Table 1.1. The natural presence of elements in the crust of the earth Table 2.1. Glass transition temperatures Table 2.2. Colors of glass resulting from doping Table 4.1. Procedures for making poly(ethylene) are described in depth Table 6.1. A list of nanomaterials that are under investigation or are being used in the industry Table 6.2. Potential applications and general classification of NPs Table 7.1. The characteristics of composites against metals are compared (Campbell, 2010) Table 8.1. The kinds of interfaces among electromagnetic waves of unlike frequencies with the matter

LIST OF ABBREVIATIONS

AES

auger electron spectroscopy

AFM

atomic force microscopy

AFP

automated fiber placement

ATL

automated tape laying

ATP

automated tow placement

BMCs

bulk molding compounds

CB

conduction band

CNTs

carbon nanotubes

CSH

calcium–silicate–hydrate

CTE

coefficient of thermal expansion

CVC

chemical vapor deposition

DLC

diamond-like carbon

DOS

density of states

DSC

differential scanning calorimetry

DSC

dye-sensitized solar cells

ECDs

electrochromic devices

EDS/EDX

energy-dispersive spectroscopy

EELS

electron energy loss spectroscopy

EMI

electromagnetic interference

EN

engineered nanomaterials

FE

field emission

FRPs

fiber reinforced plastics

GPC

gel-permeation chromatography

HCP

hexagonal close-packed

HOMOs

highest occupied molecular orbitals

LCAO–MO

conventional linear mixture of atomic orbitals–molecular orbitals

LEDs

light-emitting diodes

xix

LUMOs

lowest unoccupied molecular orbitals

MLCT

metal-to-ligand charge transfer

MW

microwave

NASA

National Aeronautics and Space Administration

NMR

nuclear magnetic resonance

NPs

nanoparticles

PECVD

plasma-enhanced chemical vapor deposition

PES

photoelectron spectroscopy

PL

photoluminescence

PVP

polyvinylpyrrolidone

RF

radio frequency

RGO

reduced graphite oxide

RTM

resin transfer molding

SAXS

small-angle X-ray scattering

SEM

scanning electron microscope

SIMS

secondary ion mass spectrometry

SMCs

sheet molding compounds

SPF

sun protection factor

SPM

scanning probe microscopy

STEM

scanning TEM

STM

scanning tunneling microscopy

TE

thermoelectric

TEM

transmission electron microscopy

TEOS

tetraethoxysilane

TFT LCDs

thin-layer transistor liquid crystal displays

TGA

thermogravimetric analysis

TIM

thermal interface material

TMOS

tetramethoxysilane

VOCs

volatile organic compounds

XAFS

X-ray absorption fine structure

XPS

X-ray photoelectron spectroscopy

XRD

X-ray diffraction

PREFACE

The application of chemistry in the design and synthesis of materials having intriguing or potentially valuable physical properties, such as optical, magnetic, structural, or catalytic capabilities, is known as materials chemistry. It also entails the characterization, processing, and understanding of these chemicals at the molecular level. Functional materials are essential components of modern civilization and play an important role in technological advancement. Materials chemistry is remarkable in that it provides the conceptual framework for designing, creating, and comprehending new forms of matter, whether organic, inorganic, or hybrid. Chemistry is generating a new world of materials for use as catalysts, molecular transporters, sensors, artificial scaffolds, light-emitting molecular filters, and electron-conducting ensembles, ranging from nanomaterials and molecular devices to polymers and extended solids, all of which have the potential for widespread scientific and societal impact. The book is divided into eight chapters. Chapter 1 introduces the readers with fundamentals of materials chemistry and the history of materials chemistry. Chapter 2 discusses the introductory concepts of solid-state chemistry and focusses on different types of solid materials. Chapter 3 illustrates the chemistry of semiconducting materials. Chapter 4 sheds light on polymeric materials and their chemistry. Chapter 5 contains information about carbon materials and their chemistry. Chapter 6 introduces the readers with the chemistry of novel nanomaterials and their chemical properties. Chapter 7 focuses on the fundamentals of composite materials and their characteristics with emphasis on the chemistry of matrix and reinforcement materials. Finally, Chapter 8 discusses different characterization techniques for investigating the properties of materials. Despite the fact that most schools and institutions today offer materials chemistry courses and degree programs, there is still a need for a textbook that covers inorganic, organic, and nano-based materials from a structure vs. property perspective. It was a challenging endeavor to try to fill this gap by offering adequate coverage of the continu-

ously growing subject of materials – all in a succinct fashion. The information presented here is best suited for junior and senior undergrads as well as first-year graduates in the disciplines of chemistry, physics, and engineering. Furthermore, this textbook will be particularly valuable for industry researchers as a starting point for learning about materials and procedures, with references supplied for further exploration.

CHAPTER

1

INTRODUCTION TO MATERIALS CHEMISTRY

CONTENTS 1.1. Introduction ........................................................................................ 2 1.2. History of Materials Chemistry ............................................................ 3 1.3. Factors in the Design of New Materials ............................................... 8 1.4. Design of New Materials Through A “Critical Thinking” Method ......... 9 References ............................................................................................... 14

2

The Fundamentals of Materials Chemistry

1.1. INTRODUCTION Life in the 21st century is increasingly reliant on an almost limitless array of modern materials. As consumers, it is simple to take for granted the nanoscopic, micro, and macro building pieces that are the foundation of every object ever manufactured. We have become spoilt by technological advancements that make our lives easier, such as digital cell phones, laptop computers, microwave (MW) ovens, and more convenient ways of public transit. We, on the other hand, rarely stop to consider and evaluate the materials that go into the construction of these modern technical marvels (Heilbron 2003; Klabunde and Richards, 2009; Wright and Sommerdijk, 2018). Material may be described as any solid-state element or technology that has the potential to be employed to meet a present or future societal requirement. Shelter, for example, can be provided by simple building materials like coatings, wood, nails, and other such items. Other, more subtle materials, like nanodevices, may not have yet been extensively demonstrated for specific uses, but they will be critical for the demands of our society in the foreseeable future. It is important to note that while the above description contains solid nanostructural building blocks that may be assembled to form bigger materials, it does not include complex liquid chemicals like fossil oil, which may be more appropriately regarded as a precursor for materials (Brush, 1988; Shirota, 2000; Von Schomberg, 2010). Figure 1.1 depicts a general explanation of the many sorts of materials, which is further explained in the text. Although this demonstrates significant boundaries between several groups, there is sometimes uncertainty over the appropriate classification for a given item. For instance, a thin film is described as having a film thickness of < 1 micron; but, if the film thickness decreases to fewer than 100 nanometers, the components may be more correctly characterized as belonging to the nanometer scale (Brock, 1993; Pasch and Schrepp, 2003). Similarly, liquid crystals are best defined as having characteristics that are midway between those of the amorphous and those of the crystalline phases, while hybrid compound materials contain both organic and inorganic components (Suslick and Price, 1999; Tatko and Waters, 2004). When taken as a whole, materials chemistry is concerned with figuring out how to comprehend the links that exist among the arrangement of the molecules, ions, or atoms that make up a material and the whole bulk

Introduction to Materials Chemistry

3

physical/structural characteristics of that material. Common fields such as surface chemistry, solid-state, and polymer would all be included under the purview of materials chemistry because of this categorization. Examining the structures and characteristics of present materials, synthesizing, and characterizing new materials, as well as employing advanced computational tools to anticipate the properties and structures of materials that have not yet been created are all part of this large field of research (Liu et al., 2005; Duer, 2008; Fahlman, 2018).

Figure 1.1. Schema of classification for the numerous sorts of building materials. Source: https://www.researchgate.net/figure/1-Classification-Scheme-for-theVarious-Composite-Types_fig1_321977658.

1.2. HISTORY OF MATERIALS CHEMISTRY Even though the education of materials chemistry is a comparatively new addition to equally graduate and undergraduate courses, it has always been an essential part of the field of chemistry. Figure 1.2 has an intriguing chronology of the evolution of materials from primitive times to the current day. To the best of most historians’ knowledge, Neolithic man (10,000–300 B.C.) was the first person to recognize that specific materials like clay, wood, and limestone were very easily shaped into materials that could be employed as weaponry, tools, and utensils (Weimerskirch, 1989; Mann, 2001). Copper was employed for a wide range of ornamental, protective,

4

The Fundamentals of Materials Chemistry

and functional purposes as far back as the Chalcolithic Age (4,000–1,500 B.C.) when it would be employed for a wide range of protective, functional, and ornamental purposes. This evolution was the first to recognize the basic properties of metals, like thermal and malleability conductivity, and to apply these properties to their construction. Chalcolithic man, on the other hand, was the first to put top-down materials into practice combination, as they established methods to remove copper from oxide ores like malachite, which they then used in a wide range of applications (Shirota, 2000; Nair et al., 2014). A chance discovery led to the discovery that doping copper with other compounds drastically altered the physical properties of the material during the Bronze Age (1,400 B.C.–0 B.C.), during which time metal alloys were first used. Arsenic-doped copper has been discovered in artifacts from the Middle East that date back to 3,000 B.C. This is because of the widespread accessibility of domeykite and lautite ores, which are both rich in arsenic and copper and can be found in abundance. However, because of the arsenic-related deaths, these alloys were immediately swapped with tin– copper alloys, which were generally employed because they had a lower brittleness, lower melting point, and higher hardness than their arsenicbased predecessors (Wilkes, 2002; Davis, 2014). The Iron Age (1,000 B.C.–1,950 A.D.) was the era in which the first applications for iron-based materials were discovered. Because the earth’s crust includes meaningfully more iron than copper (Table 1.1), it is not surprising that bronze was eventually phased out of use in the production of building materials and other products. Iron silicate, also called wrought iron, was discovered unintentionally as a by-product of copper processing, and was used as a building material (Hu et al., 2014; Kitchen et al., 2014). Table 1.1. The Natural Presence of Elements in the Crust of the Earth Element Aluminum Silicon Oxygen Iron Sodium Magnesium Calcium

Abundance 8.2% 28.2% 46.1% 5.6% 2.4% 2.3% 4.2%

Introduction to Materials Chemistry Titanium Potassium Copper Hydrogen Total

5

0.57% 2.1% 0.005% 0.14% 99.815%

Because when compared to bronze, this substance was softer., it was not widely employed till the Hittites discovered steel about 1,400 B.C. The spread of steel technology to other regions of the world was most expected a result of the Hittites’ war-related departure from the Middle East about 1,200 B.C. The Chinese improved on present iron-making technologies by developing ways for creating iron alloys that allowed iron to be molded into desired forms. Several more empirical advancements were carried out in different regions of the world during this time; nevertheless, scientists did not begin to grasp why these various processes were beneficial until the 18th and 19th centuries A.D (Hill, 1998; Hofmann and Hagey, 2014). Figure 1.2 depicts the primary materials science development activities, together with the approximate year each topic was initially explored. The creation of better ceramics and glasses, which were first discovered by the ancient civilizations, is still of ongoing interest in each of these disciplines. While architectural and structural materials like asphalt ceramics glassware have remained relatively unchanged since their conception, the world of electronics has moved rapidly. Several novel designs for sophisticated material design are undoubtedly still to be discovered, as scientists strive to replicate the fundamental structural order present in live animals and plants, which can be seen when looking at their tiny regimes (Shanahan et al., 2011). Existing materials become outdated when civilization moves on to newer technology, or their ideas are adapted to novel uses. A good instance of this is gramophones, which were widely used in the primary to mid-1900s. Nevertheless, due to the favored tape format, there was a steep reduction in record usage once Marvin Camras invented magnetic tape in 1947. The introduction of small disc technology in 1982 put the last nail in the casket of records, which are now just available at vintage stores and service department sales. The barbs that were once required to perform records are no longer commercially viable, but they have inspired another use at the micro-and nanoscale level: atomic force microscopy (AFM), often known as scanning probe microscopy (SPM) (Ali and Armstrong, 2008).

6

The Fundamentals of Materials Chemistry

Figure 1.2. Schedule of significant development endeavors in the field of materials science and engineering. Source: https://www.degruyter.com/document/doi/10.1515/ci.2009.31.3.4/html.

This materials characterization technology creates pictures of the surface topology of a sample using a tip like a record needle used in phonographs – even includes the regulated positioning of individual atoms (Figure 1.3)! As a result, even if society’s requirements and aspirations are continually altering, the obsolete materials that are being phased out may, however, be useful in the development of new materials and technologies. Without a grasp of the link between material structure and characteristics, the early world of materials discovery was based primarily on empirical findings. Each civilization had distinct demands that were met by adapting any materials were available at the time. Even though this adequately handled whatever social concerns were there at the time, like a trial-anderror approach to materials layout caused in sluggish progress (Düren et al., 2004).

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Intriguingly, the chemistry was seen as a religion until the 19th century, as it was developed from alchemical foundations that centered on a mystical desire to make meaning of the cosmos. The experimenters were on the lookout for the keys to immortality, a “philosopher’s stone” that could turn base matter into the higher matter, techniques to manufacture gold, and magical cures for ailments. Despite their great intentions, their endeavors remained unfulfilled due to a lack of a determined level theory to guide their work (Politzer et al., 2007).

Figure 1.3. Using the manipulation of Co atoms on a Cu(111) surface, we were able to create a 40-nm wide logo for the NIST. Similar to how ripples appear in a pond when stones are put in, the ripples in the background are caused by electrons in the fluid-like layer at the copper surface jumping off cobalt atoms, creating the shapes seen there. Source: https://link.springer.com/book/10.1007%2F978-94-024-1255-0.

Aside from that, their qualitative characterization was limited to their trial-and-error methods, and it was incredibly difficult to regulate the reaction circumstances, making it almost impossible to reproduce the precise operation several times. Thus, just a handful of new compounds were discovered between 1,000 B.C. and 1,700 A.D., all of which turned out to be elements like mercury, iron, and copper in later years. This organization led to the advancement of several modern chemistry experimentation techniques, but the true development of new material design can only be achieved via prescience, which depends on an intense study of local relationships among the properties and structure of a material. According to the evidence shown in this chapter, even with this expertise, many essential materials discoveries have been

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The Fundamentals of Materials Chemistry

achieved by chance—because of an unanticipated event occurring through the meticulously planned synthesis of a distinct chemical!

1.3. FACTORS IN THE DESIGN OF NEW MATERIALS The present social demand and resource availability drive the creation of novel materials. The acceptance of material, on the other hand, is mostly determined by its cost, as seen by variations in the chemical components of currencies across time. Instead of the high quantities of metals such as copper, nickel, gold, and silver seen in early coins, today’s coinage includes worthless ferrous alloys (Oermann et al., 2000). When a new technology or material is developed, it nearly usually comes with a high cost to adopt it. Consider the price of plasma televisions and computers when they were first introduced—tens of thousands of dollars! The costs of a device’s components determine its market price. In the late 1940s, just after the creation of germanium-based transistors, the price of a single transistor was around $8–10. Nevertheless, when germanium was replaced by silicon and manufacturing processes enhanced, the cost of these materials plummeted below 1-millionth of a cent! This has resulted in extraordinary increases in computing efficiency without a corresponding rise in total cost (Yaghi et al., 2003; Ok, 2016). There are two ways to material synthesis: “top-down” and “bottom-up;” Figure 1.4 shows examples of materials created using both methods. Unlike the transformation of complicated natural products into desired materials, which is mostly done from the top-down, synthetic materials are mostly made from the bottom up. This method is the simplest to grasp, and it is even used by youngsters who put together individual LEGOTM building bricks to create more sophisticated structures. Indeed, the relatively new area of nanotechnology has fundamentally altered our understanding of bottom-up procedures, moving away from the traditional technique of molding/combining large precursor materials and toward the self-assembly of individual molecules and atoms. The capacity to change the material design at the atomic level will provide researchers unparalleled control over the qualities that arise. This will open the door to a plethora of potential uses, including speedier electronic gadgets, more effective medicine delivery agents, and “green” energy options like fuel-cell and hydrogen-based technology (Arakaki et al., 2003; Nappi, 2017). Self-autonomic/repairing healing structural materials, which were recently discovered, are an instance of the next generation of “smart materials.” These materials are meant to experience rapid physical

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modification with no or little human involvement, like how our bodies are built to repair themselves. Imagine a future where building cracks heal on their own and car bodywork is restored to showroom condition immediately after an accident. These materials might be used to reduce faulty components on an assembly line over the next few decades, and they could even be used in structures that are now difficult to repair, like implanted medical devices or integrated circuits. The uses will only be restricted by our imaginations as we understand more about how to construct materials with certain qualities from basic molecular/atomic subunits (King, 1995; Fuad et al., 2017).

1.4. DESIGN OF NEW MATERIALS THROUGH A “CRITICAL THINKING” METHOD While critical thinking is necessary for logical problem solving, this way of reasoning is not taught in most bachelor and post-baccalaureate curriculum. Regrettably, the curriculum emphasizes memorizing and preparation for standardized tests. Furthermore, with television, movies, and the Internet has such a huge impact on today’s society, the concept of evoking an intentional flow diagram of thinking is not universally relevant (Muhlisin et al., 2016; Rusmansyah et al., 2019).

Figure 1.4. Illustrations for the “top-down” and “bottom-up” approach to materials synthesis.

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The Fundamentals of Materials Chemistry

Note: The top-down approach is frequently employed in the transformation of naturally occurring goods into useable building materials. (a) A few examples of the types of representations described above also include the conversion of wood into paper goods and specific types of golf ball coverings. (b) The bottom-up approach to materials synthesis is the most widely used method. Source: https://text.123docz.net/document/4814644-materials-chemistry.htm.

The manufacturing of plastics and vinyl, which can be found in everyday home items and automobile interiors, is represented in the illustration above. Polymerization processes, which begin with basic monomeric chemicals and progress through a variety of stages, may be used in any professional path. These abilities are also extremely transferable to the creation of novel materials, which is the subject of this manual. Figure 1.5 is an instance of a critical thinking flow diagram that might be used in the project of a novel material, as shown in the text (Budi and Sunarno, 2018; Tang et al., 2020).

Figure 1.5. For the design of a novel material, here is an example of a critical thinking strategy. Source: https://www.wiley.com/en-us/Introduction+to+Materials+Chemistry %2C+2nd+Edition-p-9781119347255.

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While there are several alternatives for such progress, the subsequent are critical components of each new improvement (Astleitner, 2002; Bağ and Gürsoy, 2021): •

•

•

•

Create a clear definition of the societal demand and the sort of substance that is being pursued. In other words, establish the desired qualities of the novel material before proceeding. Conduct a thorough review of the literature to establish which items are currently in use in the field. This must be completed for the new product to be competitive in the consumer and industrial markets. This ensures that wide research efforts are not unexploited by reinventing the wheel when rather previously exists and patent literature. It should be highlighted that every practice in critical thinking will improve outcomes in more questions than were expected at the start of the practice. According to the flowchart beyond, one will seek intriguing reactions/products and get underway to think about the process of action of the process when looking for interesting products/reactions. It is necessary to have a “firstprinciple” knowledge of the procedure to boost yields of the material and scale up the process for industrial applications. Following the protection of new equipment through the filing of patents, publishing in scientific publications is essential to encourage ongoing research and the development of new and advanced materials. Top scientific journals like Science, Nature, The Journal of the American Chemical Society, The Nano Letters, Advanced Materials, Chemistry of Materials, and Small publish articles every week on the most recent advancements in the most active areas of science. Nature, Science, The Journal of the Advanced Materials, The Chemistry of Materials, American Chemical Society, Small, and Nano Letters are just a few examples of the journals that publish articles every week on the most recent improvements in the most active areas of science. There has been an exponential growth in the number of articles on materials-related topics in recent years. As information continues to accumulate, it encourages greater advancement in the fields of characterization, synthesis, and modeling of materials. Nevertheless, this is only likely to occur when active researchers communicate their findings with their international peers.

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The Fundamentals of Materials Chemistry

One of the primary goals of Materials Chemistry is to give students a broad understanding of the numerous types of materials available, with an emphasis on synthetic techniques and correlations between a material’s structure and its overall attributes. A section named “Important Materials Applications” will be included in each chapter, and it will discuss an intriguing present or future application connected to a certain kind of material. Solar cells, depleted uranium, fuel cells, “self-healing” polymers, and molecular machines are some of the topics covered in these subsections (Zhou et al., 2012; Vong and Kaewurai, 2017). The following major classes of materials will be examined (Chen and Hwang, 2020): • Superconductors; • Metals; • Semiconductors; • Ceramics and glasses; • Magnetic materials; • Soft materials, like composites and polymers; • Nanostructural materials; • Thin films. It will be necessary to thoroughly detail the molecular and atomic structures of all these materials in order to fully comprehend their different qualities. We will not be capable of growing our culture with new, better materials, which will further enhance our way of life unless we have a thorough understanding of these linkages in place. Any discipline of chemistry that requires substantial characterization procedures must employ them. Using nuclear magnetic resonance (NMR) or spectroscopic methods, for example, one can determine whether the proper chemical has been created following an organic synthesis. A similar situation exists in the field of materials chemistry, where characterization methods must be utilized to validate the identification of a material, as well as to discover why a particular material has stopped, to influence the creation of new technologies. This work will provide examples of characterization procedures, which will serve as illustrations of the complex approaches that are utilized to examine the structures and characteristics of contemporary materials. As a result of the extensive coverage of common techniques in other workbooks, this book will concentrate on the methods that are commonly employed by modern materials chemists, like UV-visible

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absorption spectroscopy, atomic absorption/emission spectroscopy, NMR, mass spectrometry, and infrared spectrometry, among others: •

•

Surface/nanoscale analysis: – PES (Photoelectron spectroscopy); – SEM (Scanning electron microscopy); – AES (Auger electron spectroscopy); – EDS/EDX (Energy-dispersive spectroscopy); – TEM (Transmission electron microscopy); – XAFS (X-ray absorption fine structure); – SIMS (Secondary ion mass spectrometry); – SPM (Scanning probe microscopy); – EELS (Electron energy-loss spectroscopy). Bulk characterization: – TGA (Thermogravimetric analysis); – XRD (X-ray diffraction); – GPC (Gel-permeation chromatography); – SAXS (Small-angle X-ray scattering); – DSC (Differential scanning calorimetry).

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The Fundamentals of Materials Chemistry

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Ali, M. M., & Armstrong, P. J., (2008). Overview of sustainable design factors in high-rise buildings. In: Proc. of the CTBUH 8th World Congress (Vol. 8, pp. 3–5). 2. Arakaki, N., Nagao, T., Niki, R., Toyofuku, A., Tanaka, H., Kuramoto, Y., & Higuti, T., (2003). Possible role of cell surface H+-ATP synthase in the extracellular ATP synthesis and proliferation of human umbilical vein endothelial cells 11 grants-in-aid for cancer research (NA), scientific research (B)(TH), scientific research on priority areas of molecular synchronization for design of new materials (TH), and scientific research on exploratory research (TH) from the ministry of education, culture, sports, science, and technology, Japan. Molecular Cancer Research, 1(13), 931–939. 3. Astleitner, H., (2002). Teaching critical thinking online. Journal of Instructional Psychology, 29(2), 53–76. 4. Bağ, H. K., & Gürsoy, E., (2021). The effect of critical thinking embedded English course design to the improvement of critical thinking skills of secondary school learners. Thinking Skills and Creativity, 41, 100910. 5. Brock, W. H., (1993). Norton History of Chemistry (Vol. 1, pp. 1–26). WW Norton. 6. Brush, S. G., (1988). The History of Modern Science: A Guide to the Second Scientific Revolution, 1800–1950 (No. 04, Q125, B8.). 7. Budi, A. P. S., & Sunarno, W., (2018). Natural science modules with SETS approach to improve students’ critical thinking ability. In: Journal of Physics: Conference Series (Vol. 1022, No. 1, p. 012015). IOP Publishing. 8. Chen, M. R. A., & Hwang, G. J., (2020). Effects of a concept mapping‐ based flipped learning approach on EFL students’ English-speaking performance, critical thinking awareness, and speaking anxiety. British Journal of Educational Technology, 51(3). 9. Davis, M. E., (2014). Zeolites from a materials chemistry perspective. Chemistry of Materials, 26(1), 239–245. 10. Duer, M. J., (2008). Solid-State NMR Spectroscopy: Principles and Applications (Vol. 1, pp. 1–24). John Wiley & Sons. 11. Düren, T., Sarkisov, L., Yaghi, O. M., & Snurr, R. Q., (2004). Design of new materials for methane storage. Langmuir, 20(7), 2683–2689.

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12. Fahlman, B. D., (2018). What is “materials chemistry”?. In: Materials Chemistry (Vol. 1, pp. 1–21). Springer, Dordrecht. 13. Fuad, N. M., Zubaidah, S., Mahanal, S., & Suarsini, E., (2017). Improving junior high schools’ critical thinking skills based on testing three different models of learning. International Journal of Instruction, 10(1), 101–116. 14. Heilbron, J. L., (2003). The Oxford Companion to the History of Modern Science (Vol. 1, pp. 2–21). Oxford University Press. 15. Hill, C. L., (1998). Introduction: Polyoxometalates multicomponent molecular vehicles to probe fundamental issues and practical problems. Chemical Reviews, 98(1), 1, 2. 16. Hofmann, A. F., & Hagey, L. R., (2014). Key discoveries in bile acid chemistry and biology and their clinical applications: History of the last eight decades. Journal of Lipid Research, 55(8), 1553–1595. 17. Hu, Y., Li, C. Y., Wang, X. M., Yang, Y. H., & Zhu, H. L., (2014). 1,3,4-thiadiazole: Synthesis, reactions, and applications in medicinal, agricultural, and materials chemistry. Chemical Reviews, 114(10), 5572–5610. 18. King, A., (1995). Designing the instructional process to enhance critical thinking across the curriculum. Teaching of Psychology, 22(1), 13–17. 19. Kitchen, H. J., Vallance, S. R., Kennedy, J. L., Tapia-Ruiz, N., Carassiti, L., Harrison, A., & Gregory, D. H., (2014). Modern microwave methods in solid-state inorganic materials chemistry: From fundamentals to manufacturing. Chemical Reviews, 114(2), 1170–1206. 20. Klabunde, K. J., & Richards, R. M., (2009). Nanoscale Materials in Chemistry (Vol. 1, pp. 4–27). John Wiley & Sons. 21. Liu, Y., Radke, W., & Pasch, H., (2005). Coil−stretch transition of high molar mass polymers in packed-column hydrodynamic chromatography. Macromolecules, 38(17), 7476–7484. 22. Mann, S., (2001). Biomineralization: Principles and Concepts in Bioinorganic Materials Chemistry (Vol. 5, pp. 1–23). Oxford University Press on Demand. 23. Muhlisin, A., Susilo, H., Amin, M., & Rohman, F., (2016). Improving critical thinking skills of college students through RMS model for learning basic concepts in science. In: Asia-Pacific Forum on Science Learning and Teaching (Vol. 17, No. 1, pp. 1–24). The Education

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University of Hong Kong, Department of Science and Environmental Studies. Nair, D. P., Podgorski, M., Chatani, S., Gong, T., Xi, W., Fenoli, C. R., & Bowman, C. N., (2014). The thiol-Michael addition click reaction: A powerful and widely used tool in materials chemistry. Chemistry of Materials, 26(1), 724–744. Nappi, J. S., (2017). The importance of questioning in developing critical thinking skills. Delta Kappa Gamma Bulletin, 84(1), 30. Oermann, M., Truesdell, S., & Ziolkowski, L., (2000). Strategy to assess, develop, and evaluate critical thinking. The journal of Continuing Education in Nursing, 31(4), 155–160. Ok, K. M., (2016). Toward the rational design of novel noncentrosymmetric materials: Factors influencing the framework structures. Accounts of Chemical Research, 49(12), 2774–2785. Pasch, H., & Schrepp, W., (2003). MALDI-TOF Mass Spectrometry of Synthetic Polymers (Vol. 1, pp. 5–21). Springer Science & Business Media. Politzer, P., Murray, J. S., & Concha, M. C., (2007). Halogen bonding and the design of new materials: Organic bromides, chlorides, and perhaps even fluorides as donors. Journal of Molecular Modeling, 13(6), 643–650. Rusmansyah, R., Yuanita, L., Ibrahim, M., Isnawati, I., & Prahani, B. K., (2019). Innovative chemistry learning model: Improving the critical thinking skill and self-efficacy of pre-service chemistry teachers. JOTSE: Journal of Technology and Science Education, 9(1), 59–76. Shanahan, C., Shanahan, T., & Misischia, C., (2011). Analysis of expert readers in three disciplines: History, mathematics, and chemistry. Journal of Literacy Research, 43(4), 393–429. Shirota, Y., (2000). Organic materials for electronic and optoelectronic devices: Basis of a presentation given at materials chemistry discussion No. 2, University of Nottingham, UK. Journal of Materials Chemistry, 10(1), 1–25. Suslick, K. S., & Price, G. J., (1999). Applications of ultrasound to materials chemistry. Annual Review of Materials Science, 29(1), 295– 326.

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34. Tang, T., Vezzani, V., & Eriksson, V., (2020). Developing critical thinking, collective creativity skills and problem-solving through playful design jams. Thinking Skills and Creativity, 37, 100696. 35. Tatko, C. D., & Waters, M. L., (2004). Effect of halogenation on edge− face aromatic interactions in a β-hairpin peptide: Enhanced affinity with iodo-substituents. Organic Letters, 6(22), 3969–3972. 36. Von, S. R., & Davies, S., (2010). Understanding Public Debate on Nanotechnologies (Vol. 1, pp. 1–20). Publication Office of the European Union, Luxembourg. 37. Von, S. R., (2010). Introduction: Understanding Public Debate on Nanotechnologies Options for Framing Public Policy (Vol. 1, pp. 2535). 38. Vong, S. A., & Kaewurai, W., (2017). Instructional model development to enhance critical thinking and critical thinking teaching ability of trainee students at regional teaching training center in Takeo province, Cambodia. Kasetsart Journal of Social Sciences, 38(1), 88–95. 39. Weimerskirch, P., (1989). In: Ellis, M., (ed.), Milestones in Science and Technology: The Ready Reference Guide to Discoveries, Inventions, and Facts (Vol. 1, pp. 75–80). Barbara A. List. ISIS. 40. Wilkes, J. S., (2002). A short history of ionic liquids—From molten salts to neoteric solvents. Green Chemistry, 4(2), 73–80. 41. Wright, J. D., & Sommerdijk, N. A., (2018). Sol-Gel Materials: Chemistry and Applications (Vol. 1, pp. 1–20). CRC Press. 42. Yaghi, O. M., O’Keeffe, M., Ockwig, N. W., Chae, H. K., Eddaoudi, M., & Kim, J., (2003). Reticular synthesis and the design of new materials. Nature, 423(6941), 705–714. 43. Zhou, Q., Ma, L., Huang, N., Liang, Q., Yue, H., & Peng, T., (2012). Integrating WebQuest into chemistry classroom teaching to promote students’ critical thinking. Creative Education, 3(3), 369.

CHAPTER

2

SOLID-STATE CHEMISTRY

CONTENTS 2.1. Introduction ...................................................................................... 20 2.2. Amorphous Vs. Crystalline Solids ...................................................... 20 2.3. Types of Bonding In Solids ................................................................ 22 2.4. The Crystalline State.......................................................................... 30 2.5. The Amorphous State ........................................................................ 33 References ............................................................................................... 47

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2.1. INTRODUCTION Solids have the largest structural variety out of three forms of matter. Solids are made up of atoms, molecules or ions that are stable in their position, while gases and liquids are made up of distinct molecules that really are randomly dispersed because of thermal motion. To completely comprehend the characteristics of solid materials, a detailed understanding of the structural connections among the constituent atoms, molecules, and ions, is required. This chapter will cover several forms of solids, as well as the structural classifications and terminology both for amorphous and crystalline solids. The information in this important chapter will lay the framework for the entire book, which covers a wide range of courses of materials (Glusker et al., 1996; Pogge, 1996).

2.2. AMORPHOUS VS. CRYSTALLINE SOLIDS A solid is a substance that, over time, keeps the volume as well as shape. The solid is defined as crystalline if it has long-range, recurring components. Only if the ions, atoms, or molecules get the chance for organizing themselves in a regular configuration, or matrices, a crystal-like solid can form. For instance, crystalline minerals discovered in nature were produced over thousands of years of tremendous heat and pressure, or via gradual evaporation processes. The majority of naturally occurring crystalline solids are composed of aggregates of microcrystalline units; single crystals free of substantial faults are exceedingly rare in nature and need specific growth processes (Larminie et al., 2003; West, 2014). If the solid lacks large-range structural organization, it is the best defined as an amorphous. Quite frequently, these materials exhibit a high degree of short-range order. However, this family of materials is distinguished from their crystalline counterparts by the absence of lengthy translational order (periodicity). Due to the fact that the bulk of research has focused on crystalline solids in comparison to the amorphous competitors, it is the widespread misperception that, nearly all solids are crystal-like by nature (Clearfield, 1988; Felser et al., 2007). Indeed, unless additional processes are utilized to enhance molecular ordering, a solid product formed by several chemical reactions would be amorphous by nature (i.e., crystal development). Even though a crystalline form is extra thermodynamically advantageous as compared to the disordered phase, amorphous materials are formed more frequently in kinetically bound procedures (e.g., chemical

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vapor deposit, sol–gel, solid precipitating, etc.) (West, 1999; Smart and Moore, 2012). Several materials with long molecular webs, like glasses, might not ever occur in a crystal form. Because the molecules in these materials are so tangled or geometrically complicated, crystallization may not happen when the temperature is gradually reduced (Koinuma and Takeuchi, 2004). These compounds are properly referred as the supercooled liquids because of the stiffness of the solid but tendency to persist in the amorphous form. It was originally considered that the gradual movement of glass over centuries led the base of 19th century-stained glass windows to be correspondingly thicker. Nonetheless, this is now generally established that until the glass structure’s threshold transition temperature is surpassed, the structure remains intact. A transition temperature of glass, Tg, is a temperature under those molecules have really limited mobility (Elliott, 1998; Hurd, 1975). A few other amorphous substances, like polymers, display similar characteristic as well, being hard as well as stiff under Tg and flexible above it. The transition temperatures of glass, typical solid materials are listed in Table 2.1. Though textbooks based on most of solid-state focus entirely on crystal-like materials, this book would try to cover both crystalline and amorphous states, detailing the structure/property correlations of important amorphous types like polymers and glasses (Schnick, 1993; Byrn et al., 1994; Pöttgen et al., 2006). Table 2.1. Glass Transition Temperatures Material SiO2 Borosilicate glass Pd0.4Ni0.4P0.2 BeF2 As2S3 Polystyrene Se∞

Intermolecular ing Covalent Covalent Metallic

Bond- Tg(°C) 1,430 550 580

Ionic Covalent Van der Waal Covalent

570 470 370 310

Poly(vinyl chloride)

Van der Waal

81

Polyethylene

Van der Waal

30

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The Fundamentals of Materials Chemistry

2.3. TYPES OF BONDING IN SOLIDS Each crystalline and amorphous solid is governed by firm sorts of interas well as intra-molecular connections among its subunits. A range optical, electronic, and physical characteristics are seen depending on the type and intensity of these interactions. As predicted, these linkages affect not just the solid-state properties of the material, but as well as the fewer organized liquid stage (Brbot-Šaranović et al., 1986; Zong et al., 2016). For instance, the hydrogen bonding connections among adjacent water molecules inside an ice lattice are as significant in the liquid state, leading to a large surface tension and limited viscosity. Intermolecular forces have indeed been eliminated in the gaseous state, and they no longer affect its characteristics (Saleki-Gerhardt et al., 1994; Gupta, 1996).

2.3.1. Ionic Solids These types of solids are distinguished by a presence of anions as well as cations which are linked by electrostatic connections (Tosi, 1964; Singh, 1982). As shown by popular Group 1–17 or 2–17 binary salts like CaCl2 and NaCl, all only ionic salts have crystal-like forms (Figure 2.1).

Figure 2.1. Ionic model for sodium chloride.

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Note: The chloride ions (white) are arranged face-centered, along sodium ions covering the octahedral interstitial spaces (red). An electrostatic force of attraction, a, among nearby Na+ and Cl ions are shown, as well as the repulsive electrostatic forces, r, among Na+ ions (Kurmaev et al., 1992; Cheng et al., 2021). Source: https://www.ck12.org/book/ck-12-chemistry-intermediate/section/8.2/.

Since a very solid electrostatic interactions among counterions should be broken, the melting temperature of such solids are extraordinarily high. While oppositely charged ions attract one other, similar charge repel each other. The size and charge of ions are the most essential factors in determining the lattice energy, U. (Eqn. (1)). This is, the lattice energy of MgO will be substantially higher than the BaO, and meanwhile the magnesium salt’s ionic bonding is much tighter because of its high charge/ small volume (density with large charge). MgN, on the opposite hand, does not occur, despite the fact that Mg3+ and N3- will be powerfully attracted by electrostatic connections. The amount of ionization energy necessary for the creation of the trivalent magnesium ion is just too high (Krikorian and Sneed, 1979; Weinstein et al., 1981).

(1) 23

–1

where; N (6.02 × 10 molecules mol ) is Avogadro’s number; Zcation,anion is the intensity of ionic charges; r0 is the average length of an ionic bond; e is the electronic charge (1.602 × 10–19 C); Permeability of a vacuum is 4πε0 (1.11 × 10–10 C2 J–1 m–1); M stands for Madelung’s constant; ρ is the exponent of Born. The Born exponent and Madelung constant in Eqn. (1) refer to a precise configuration of ions in a crystalline lattice. The Madelung constant might well be supposed of as a diminishing series that accounts for repulsions and attractions between ions of comparable charge and oppositely charged ions. Each salt or chloride ion, for instance, is covered by six ions of oppositely charged in NaCl lattice shown in Figure 2.1, resulting in a strong force of attraction. However, because there are 12 ions with similar charges farther away, the repulsive interaction is weaker. When all ions in the infinite crystal lattice are considered, the quantity of potential connections grows continually; however, intensities of these forces decrease to zero (Ackerman et al., 1981; Johari, 1991; Sebhatu et al., 1994).

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Because of the dipole-dipole connections among constituent ions and the solvent, ionic solids are really the only ones solvable in highly polar solvents. A solubility of ions (i.e., production of [(H2O)nNa]+) shows a large exothermic activity that would be the key strength for this to happen, because the crystal’s lattice energy must be resolve in this process (Novak, 1974; Aliev and Harris, 2004).

2.3.2. Metallic Solids Physical features such as strong electrical and thermal conductivity and high, malleability, and ductility distinguish metallic solids (i.e., capable to be shaped in the thin wire). Metals have little ionization energies chemically, which makes them quickly oxidized by the surrounding environment (Glasser and Jenkins, 2000; Swaminathan et al., 2007). This describes those metals are present in nature as oxides, sulfates, silicates, aluminates, and other complicated geological forms. It is worth noting that alloys and metals might be as liquids as well STP. Mercury seems to be the one and only pure metal which can be found in liquid form at STP. The electrical arrangements of Hg’s individual atoms are responsible for its liquid state. A full shell of 4f electrons shields the 6s outer shell electrons from the nuclear charge. Because of the shielding, the effective charge of nucleus (Zeff) of these electrons is larger, resulting in less valence electron sharing/delocalization as compared to other metals. Furthermore, the 6s orbital’s relativistic contraction brings these electrons nearer to the nuclei, make them fewer existing to share with surrounding Hg atoms (Naguib and Kelly, 1975; Keppens et al., 1998). Mercury seems to be the one and only metal in the gas phase which does not produce diatomic molecules. Isolated atoms do not pack in the solid matrix because the energy needed to extract electrons from outermost shell is not compensated by the lattice energy (Cargill III, 1970; Mori-Sánchez et al., 2002). Metal bonding is the best defined as like densely packed arrangement of atoms along delocalized valence electrons across the extended structure. Physical properties like as sharp melting temperatures and elasticity are the outcome of this close chemical contact between the solid’s atoms. When a metal is bent, the non-directional bonding enables two different types of deformation to occur. Within the crystal lattice, that either atomic distance between neighboring metal atoms changes (elastic distortion) or the metal atoms’ surfaces migrate past one to other (plastic distortion). Plastic distortion leads in the production of a material with “positional memory” (for instance, springs), while elastic deformation leads in the formation of a

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25

solid that retains its distorted state (Hanneman and Westbrook, 1968; Zhong et al., 2020). Pharmacists are acquainted with the conventional linear mixture of atomic orbitals–molecular orbitals (LCAO–MO) diagrams for diatomic metals like Li or Na. Metals with d orbitals (Figure 2.2) have an extra complicated overlap as compared to those with easy s and p orbitals. According to the LCAO– MO bonding hypothesis, the quantity of molecular orbitals produced must equal the quantity of atoms joined (e.g., MOs with two bonding as well as two antibonding created while in covalent form, four atoms contact). As an instance, it would be an Avogadro’s number of atoms of copper in 63.5 g (1 mol) of copper, equating to 6.022 × 1023 tightly spaced molecular orbitals!

Figure 2.2. An extended metal network with d-orbital overlap between neighboring metal atoms. Source: https://chemistry-europe.onlinelibrary.wiley.com/doi/10.1002/ chem.200600564.

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The Fundamentals of Materials Chemistry

The E≈0 among energy stages between bonding as well as antibonding areas decreases when the quantity of atoms grows to infinity, as in a crystal matrix. This is owing to the fact that nearby atoms in a crystalline structure interact more than atoms in gaseous or liquid state molecules, which are more static. Figure 2.3 depicts the energy stages of same nuclear diatomic Ti2 molecule; when the quantity of titanium atoms becomes infinite, the energy stages in solids are better represented as bands than distinct MO energy states. There is not a difference among the highest occupied molecular orbitals (HOMOs) and the lowest unoccupied molecular orbitals (LUMOs) in metals (LUMOs). An outer most shell group is the electron-occupied band, while the unoccupied band is called the conduction band (CB). The bandgap, Eg, is the energy gap among such levels. Although Eg < 0.01 eV (ca. < 1 kJ/mol) for metals and alloys, the values are on the order of 190 kJ mol–1 and >290 kJ/mol, correspondingly, for insulators and semiconductor (Cooper, 2017).

Figure 2.3. A band figure for titanium metal that shows the continuity between the valence band and conduction band (i.e., no bandgap).

Note: At absolute zero, the Fermi level is the uppermost occurring energy level (imagine adding coffee (electron) into the cup (valence band) – the peak of a liquid stage symbolizes the Fermi level/energy). Source: https://www.researchgate.net/figure/Schematic-energy-band-diagramsof-Ti-TiO2-n-Si-contact-before-and-after-300-o-C-or-500-o_fig2_303444281.

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2.3.3. Molecular Solids This type of solids is composed of individual molecules held with one another by relatively weak intermolecular interactions like dipole-dipole, hydrogen bonding and London Dispersion. Due to the fact that these kinds of forces are substantially feebler than those of ionic or metal bonding, molecular solids often have low melting temperatures. Ice (H2O), dry ice (CO2), solid methane (CH4), sugar (which is composed of different configuration of C6H12O6 molecules), and polymeric materials are all examples. Melting temperatures of polymeric materials vary greatly based on a property of the interactions between the polymer subunits (Georgiou and Koubenakis, 2003; Yu, 2010). Molecular solids can be amorphous or crystalline based on the difficulty of isolated molecules that comprise the majority of substance. As with other solids, the way more complicated the subunits, the more difficult it is for molecules to repetitively form themselves, leading to an amorphous form. In contrast to pure ionic solids, molecular composites are solvable in both nonpolar and polar solvents unless the solvent polarity of the solute and the solvent match (“like dissolves like”). Dipole-dipole interactions and London Dispersion interactions both are subcategories of van der Waal contacts. Whenever two polar molecules come into contact, a natural force of interaction between their oppositely charged ends called dipole-dipole forces are formed. Eqn. (2) may be used to indicate the relative strength of dipole-dipole forces (Bilkadi et al., 1975; De Gusseme et al., 2008):

(2) where; µ is the dipole moment of the molecular dipole (Debyes); R is the mean separation distance (A); T is the absolute temperature (K); and k seems to be the Boltzmann constant (1.38065 × 10–23 J K–1). Along with the mutual attraction of polar molecules, a connection among the solute molecules and the liquid or gas solvent may occur. In strongly polar solvents like water or alcohols, the polar molecules are surrounded by a thick shell of solvent molecules. While this solute/solvent contact contributes to the molecules’ solubility in solvent, it suppresses the dipoledipole connections among separate molecules.

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The Fundamentals of Materials Chemistry

In comparison to dipole-dipole interactions, London Dispersion attractions are significantly feebler in nature because they include nonpolar molecules which lack persistent dipole moments. Molecular attraction can only occur via electron polarization, which results in the formation of tiny dipole-dipole contacts as well as mutual attractive forces. Due to the fact that electron polarization happens far more freely for electrons located far from a nucleus, that effect is stronger for larger molecules with a larger number of electrons, particularly those attached to atoms with such a high atomic number and composed of much more diffuse orbitals. At lower temperatures and pressures, these “induced dipole” factors are necessary for a liquefaction of gases like He and Ar. Eqn. (3) defines the relative force of London Dispersion forces: (3) where; I is the molecule’s ionization potential and α is the molecule’s polarizability. A dipole-induced dipole interaction may arise when the polar as well as nonpolar molecules are present. The strength of association in this case may be calculated using Eqn. (4), which is based on both the dipole moment of a polar molecule and the polarizability of a nonpolar component. Yet again, this relationship does not take into account contacts among the polar molecule and the solvent molecules: (4) Hydrogen atom bonding may well be thought of as a subset of dipoledipole interactions, in which very strong interactions exist among strongly polar molecules. This contact is frequently denoted as A HB, indicating that a hydrogen bond is generated among a Lewis basic group (B) and hydrogen that is covalently bound to an electronegative group (A). The intensities of these connections (ca. 12–30 kJ mol–1) are typically significantly less than those of a covalent bond. Though, the straight F–H–F anion found in concentrated hydrofluoric acid does have a bond energy of around 50 kJ mol–1, making it the strongest hydrogen bond observed to date (Figure 2.4).

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Figure 2.4. Instances of h-bonding in (a) water/ice; and (b) the HF2 ion in liquid hydrogen fluoride are shown. Source: https://study.com/academy/answer/between-hf-and-h2o-which-onehas-the-greater-intermolecular-force.html.

The level of hydrogen bonding has an effect on a wide variety of a composite’s physical characteristics, including boiling and melting temperatures, dielectric constants, vapor pressure, heat capacity, refractive index, fluidity, and solubility behavior (Holmes et al., 2016).

2.3.4. Covalent Network Solids The directed covalent connections between the component atoms of these solids are very strong. Sharp melting temperatures and bulk hardness are usually the result of this bonding array. As illustrated by the highly varied qualities displayed by three allotropes (i.e., distinct structural forms) of carbon, a range of physical characteristics can be noticed because of the organization of the atoms that make up these solids (Moulton and Zaworotko, 2001; Turner et al., 2008). Diamond, for example, is an incredibly solid, insulating substance which really is translucent to light, but graphite is indeed a black, soft solid having ability of conducting electricity all with extended solid’s graphitic layers. Buckminsterfullerene (C60) is unlike any of these carbon forms in that it can be dissolved in aromatic solvents and so conduct chemical reactions. Quartz (SiO2)x, (BN)x, (ZnS)x, (HgS)x, and the two allotropes of Selenium–Grey (Se) and Red (Se8)X are all examples of covalent network solids (Culp et al., 2002; Taynton et al., 2014).

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2.4. THE CRYSTALLINE STATE A single crystal is made up of an unlimited number of molecules, ions, or atoms, collectively referred to as the crystal lattice. The lattice energy is a measure of the intensity of interactions among the species that make up the crystal. It is based on the kind and level of interactions among nearby species. For instance, salts’ extraordinarily high melting temperatures are directly proportional to the intensity of the ionic connections among nearby ions. For molecular classes, the lattice energy is determined by the strength of intermolecular forces like van der Waal and hydrogen bonding forces. Metallic crystals have the lowest lattice energy (ca. 400–500 kJ mol–1). Covalent and ionic crystals have comparable lattice energies (ca. 700–900 kJ mol–1). By comparison, molecular crystalline particles like solid carbon dioxide are considerably more easily broken into separate molecules (ca. 5–20 kJ mol–1) owing to the lattice’s weak Van der Waals interactions (Juodkazis et al., 2006; Shportko et al., 2008). Ions, molecules, or atoms are arranged in such a way that the crystal lattice’s total free energy is minimized. There is a total charge balance between all ions in an ionic crystal. Nonionic crystals have a wider range of packing relations among basic molecules. Hydrogen bonding is one of the most powerful factors in these lattices. The molecules will compact in a way that the number of donor and acceptor hydrogen bond groups is balanced. Frequently, a remaining polar solvent capable of hydrogen bonding plays a significant role in the noticeable packing arrangement. Based on the divergence of the enclosed solvent, different configurations of molecules in the crystal lattice will be seen, with hydrophilic and hydrophobic sets specially oriented relative to one another and the solvent. Empirical observations may be made about the arrangement of molecules within the crystal. While X-ray diffraction (XRD) is utilized to establish the positions of the majority of atoms, neutron diffraction is much effective for positioning hydrogen atoms (Figure 2.5) (Peter et al., 2002).

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Figure 2.5. Diagram illustrating three frequently used ways for growing single crystals.

Note: (a) diffusion, in which vapors from a volatile “nonsolvent” come into contact with the crystallization of solvent; (b) interfacial, in which the nonsolvent is covered on peak of the crystallization solvent; (c) sublimation, in which the solid combination is heated and the vapors phase crystallites on the plane of a cold finger. The crystallization beaker might well be started opening to air all through the sublimation procedure (dynamic vacuum) or locked after sustaining first space to permit for gentler crystal formation (static vacuum). Source: https://link.springer.com/book/10.1007/978-1-4020-6120-2.

Based on an extent to which a solvent is encased inside the crystal matrix, the encapsulated solvent may occasionally leak out, a phenomenon called efflorescence. In comparison, if the solid includes ions along such a large energy density (large ratio of charge and size) and is water solvable, the crystals will rapidly absorb and perhaps convert water from

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the atmosphere. Calcium chloride is the case of a deliquescent crystal. It is used as a dehydrator to remove humidity from a movement of inert gases (Kawano and Fujita, 2007). The term “morphology” refers to the general form or shape of a crystal. Frequently, the same material exists in many crystalline forms. Each of these forms is referred to as a polymorph, as they differ in terms of both component arrangement and unit cell size. While polymorphs vary in terms of the form as well as volume of the cell, most substances display this activity given the right experimental circumstances. The most common causes of crystal structure change are identical ionic ratios of ionic species in ionic crystals, or pressure or temperature fluctuations at the time of crystal formation. These latter processes modify the degree of instability in the crystal lattice, enabling atoms/ions/molecules to migrate towards thermodynamically unfavorable lattice locations at lesser temperatures and/or pressures (Figure 2.6) (Mott, 1969).

Figure 2.6. There are models of the 14 Bravais lattices. The various types of Bravais centering are indicated by the symbols P (primitive/simple), F (facecentered), I (body-centered), and C (complex/complex) (base-centered). The basic rhombohedral Bravais lattice, abbreviated R, is a trigonal symmetry primitive unit cell. Source: https://lamma.engineering.unt.edu/sites/default/files/class14_handout_mtse_3010_2018.pdf.

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Polymorphs are classified as allotropes when the solid is indeed an element. Group 16 elements exhibit one of the most well-known instances of elemental polymorphism (allotropy) (Chalcogens). Sulfur, for example, Sulphur can be in the familiar yellow powder shape phase composed of eight-membered ring configurations (Komarneni et al., 1999; Chandradass and Balasubramanian, 2006). At higher temperatures, however, a polymeric material is created that when slaked yields an endless chain of disordered Sulphur atoms (catena sulfur, or “plastic sulfur”). The remaining Group 16 congeners exhibit a similar degree of structural variation, with the structure with the lowermost total free energy determining the comparative thermodynamic sustainability of a specific allotrope. Typically, the energy required for interconversion among polymorphs is negligible, resultant as phase transitions that happen in response to just minor temperature or pressure changes. By and large, applying pressure to a crystal brings surrounding atoms closer together, reducing the size of a unit cell and increasing the coordination number of separate atoms. At pressures greater than 50 GPa, silicon, for example, undergoes a transformation from a four-coordinate polymorph to a 12-coordinate “SI VII” phase (Hancock and Zografi, 1997; Yanagisawa and Ovenstone, 1999).

2.5. THE AMORPHOUS STATE So far, we have concentrated on materials with a very well crystal-like structure. Now it is period to look at some instances of amorphous solids. We have now covered the formation of amorphous metals, which are metals produced under rapid nonequilibrium circumstances. However, there are two major kinds of amorphous materials, i.e., glasses, and ceramics. Though a bulk of ceramic materials have an amorphous structure initially created at the low temperatures, when their temperature rises, these materials are transformed to crystalline stages, a technique known as annealing. This produces a highly hard ceramic material with a high melting temperature, which is useful for structural requirement or those that occur in harsh conditions like high temperatures and/or pressures (Bouvard et al., 2013; Qi et al., 2014).

2.5.1. Sol–Gel Processing The sol–gel (solution–gelation) technique is a flexible solution-based technology used to create glassy and ceramic materials. Generally, the

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sol–gel process entails the creation of a sol (colloidal dispersion of around 200 nm solid elements) followed by crosslinking to create a viscous gel. Despite the fact that this technology has been in use since the 1930s, the complicated mechanics included in sol–gel have only lately been studied (Chen et al., 1986; Li et al., 1991). Metal alkoxide complexes (M(OR)x, where R = alkyl group) sensitive to water, are the most often utilized initial precursors or materials in the synthesis of the sol (e.g., CH3, C2H5, CF3, etc.). Although sodium silicates were utilized in the initial formulations, the usage of alkoxide precursors prevents unwanted salt byproducts that can only be eliminated by extensive, repetitive washing methods. Furthermore, the composition of a metal and accompanying R groups can be changed to influence the rate and qualities of the final oxide material (Klein, 1985; Pope and Mackenzie, 1986). Typically, sol–gel syntheses are performed during the existence of polar solvents like alcohol or water media, that enhance two fundamental processes of hydrolysis as well as condensation (Eqns. (5) and (6), correspondingly). The molecular weight of the oxide product steadily rises during the sol–gel process, finally generating a very viscid three-dimensional net (step-growth polymerization). M-OR + H2O → M-OH + ROH

(5)

M-OR + M-OH → [M-O-M]n + ROH

(6)

The most likely found metal alkoxides are Si(OR)4 composites like tetraethoxysilane (TEOS) and tetramethoxysilane (TMOS). Several alkoxides of Al, B, Ti, though, are often utilized in the sol–gel procedure and are frequently combined with TEOS. Aluminum silicates, for example, can be produced by hydrolysis/condensation of siloxides that then pass thru the intermediate Al–O–Al network called alumoxanes. Alumoxanes are significant for antiperspirant uses (Figure 2.7) (Schubert et al., 1995; Jillavenkatesa and Condrate, 1998).

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Figure 2.7. Core structure comparison of (a) siloxy-substituted alumoxane gels with (b) diaspore; and (c) boehmite minerals. The atoms of oxygen and aluminum are depicted in red and blue, correspondingly. Source: https://pubs.acs.org/doi/pdf/10.1021/cm00019a033.

Their production is best characterized as Al(O)(OH) units along a central structure similar with that of mineral chemicals or substances on the surface (Figure 2.8) (Schubert, 2005; Singh et al., 2014).

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Figure 2.8. Illustration of the products obtained through sol–gel processing. Source: https://www.researchgate.net/figure/Different-sol-gel-process-steps-tocontrol-the-final-morphology-of-the-product-58_fig3_326015773.

2.5.2. Glasses Glass-based products have historically played a significant part in our civilization, from drinking containers and window to eyewear. Indeed, uses for glass are believed to stretch all the way back to around 3,500 B.C. in Egypt. Though transparent silica-based (SiO2) glass is the most recognizable, there are several additional varieties of glass that may be made for a variety of uses. For example, infrared-transmitting chalcogenide glasses like As2E3 (E = S, Se, Te) are well suited for specific applications like optical storage, infrared lasers, and sensors. Metals may be produced in such a way that their bulk structure is disordered (Davidge and Green, 1968; Chan et al., 2002). By definition, the phrase “glass” refers to an architectural style rather than a specific substance – an amorphous solid which has frozen to stiffness without crystallizing. Glasses are frequently formed by fast cooling a melt; as a result, the component atoms are prevented from migrating into proper crystalline lattice locations. It is worth noting how transparent a solid as chaotic as glass is. That really is, the amorphous phase of glass would significantly improve transparency, which is the degree to which visible light is hindered by the substance through which it passes. Consider single crystals, which will seem transparent if their lattice spaces are less than the

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visual variety of wavelengths (about 300–700 nm). Glass seems transparent in the same way, as the degree of misalignment really covers a path shorter as compared to the wavelength of observable light (Rayleigh scattering, Eqn. (7)). Nevertheless, if the glass has flaws and/or metal or bigger particle intrusions, it becomes extremely opaque (Figure 2.9) (Malta and Carlos, 2003; Wang et al., 2007).

(7) where; n is the variation in index of refraction; and d is the spatial extent occupied by the disorder d.

Figure 2.9. Unit cell of the α-quartz crystal lattice. Source: https://jp-minerals.org/vesta/en/features.html.

The simplest way to manufacture ordinary SiO2 glass, also called quartz glass or fused silica, would be to melt and at the temperature of 1,800– 2,000°C. Dissimilar to other glasses, which need a quick slaking event to generate a glassy solid, quartz becomes a glassy solid automatically at all nevertheless the gentlest cooling speeds—a result of its complicated crystal structure. For instance, it is believed that natural quartz takes hundreds of thousands of years to produce! Fused silica is thermostable up to approximately 1,665°C. Additionally, the coefficient of linear expansion is 5.5 × 10–7 cm cm–1 K–1; in contrast, the melting point as well as coefficient

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of linear expansion of standard window pane glass a λ re around 500°C and 9.0 × 10–6 cm cm–1 K–1, respectively (Chan et al., 2001; Padilla et al., 2006): While quartz’s mechanical qualities make it ideal for high-temperature uses, it is extremely difficult to form using typical glass-blowing procedures. Quartz glass is clear to ultraviolet light (λ = about 190–300 nm), suggesting as the spatial scope of structural misalignment is smaller than that of other glasses which contain additives (vide infra). Resulting that, quartz windows are used to house UV lights, which are critical in a variety of fields such as engineering, chemistry, biology, and materials research (Wohlfarth, 1980; Kang et al., 2015). Glass chemistry has developed into a mature subject, with several varieties attainable through the mixing of oxides. To compensate for SiO2’s unreasonably high melting point, around 18% sodium carbonate (“soda,” Na2CO3) is frequently added to sand. This is the other advantageous use of the freezing-point depression collinearity, which is educated in beginning physical chemistry (for example, adding salt to icy roads in winters). Na+ ions are damaging to completed glass because they are normally dissolved in water, resulting in corrosion (Zhang et al., 1998; Takahashi et al., 2005). To efficiently substitute the sodium (Na+) ions along Ca2+, approximately 10% of lime (CaCO3) is pour to the mix. Whenever this combination is heated to its melting temperature (about 1,000°C), it forms a solution of calcium silicate (CaSiO3) as well as sodium silicate (Na2SiO3). After cooling, the common type of glass is formed, referred to as “crown glass” or soda-lime glass. This form of glassware considers for more than 90% of all glass utilized on a global scale. Interestingly, our present synthetic technique has remained consistent with the original glassmaker’s formula, that also utilized white stone pebbles (quartz, SiO2) as well as plant ash, including sodium- and calcium-based additions (Na2O and lime (CaO), correspondingly (Decreton et al., 2004; Palza et al., 2013). There are a variety of alternative glass recipes that might be utilized to get the necessary qualities. Most likely, these compositions were found accidentally or by trial and error, by experimenting with local materials and observing the resulting qualities. For example, Europe was the first one to realize that K2O, which could be produced at local from plant waste, can be coupled with lime and quartz to produce a potash-lime glass that was future used in stained-glass windows. The other common version uses boric oxide (B2O3) in place of lime and soda to produce borosilicate glass. This glass has similar physical properties as fused silica (e.g., thermal expansion

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coefficient: 3.3 × 10–7 cm–1 K–1), except that its melting point is only around 700°C. Borosilicate glass is the brand name for the kitchenware and laboratory equipment marketed in shops as PyrexTM. These applications require a glass that is resistant to heat expansion (i.e., cracking) caused by severe temperature fluctuations (Schöning et al., 2000; Hanada et al., 2004). PbO was not replaced for lime in glass compositions till the late 17th century. This “soda–lead” glass is just what you understand as crystalline material (pre-Civil War America referred to it as flint glass), and it has long been associated with luxury and excess via the use of costly glassware and chandeliers. To legally be designated as “full lead,” a crystal must have at least 24% lead oxide in its assembly. Lead provides substantial weight to the glass while boosting its refractive index. This latter attribute contributes to the crystal glassware’s well-known clear, glittering look. Additionally, the lead content causes a glass to be softer as compared to standard varieties, which must be chopped with such a diamond saw. Black crystal is, without a doubt, the most magnificent material for contemporary creative design. A mixture of chemicals – generally Fe2O3, CuO, MnO2, and Co2O3 – contributes to the lack of transparency (Bendicho and de Loos-Vollebregt, 1990; Goldman et al., 2009). That since establishment of the first churches, before to the 10th century, colored glass has been utilized. Although ornamental applications account for the bulk of colored glass applications, several Utilitarians use like traffic light signals have emerged in recent years. Glass acquires its hues as a consequence of dopant species introduced during manufacture. Either transition metal ions or colloidal suspensions produce visible color, the hue of which is proportional to the concentration utilized. Color and intensity variations are also highly dependent on the warming region (both temperature and exposure durations) utilized in the glassmaking process. By and large, the seen color is a complement of an ion’s absorbed color. That is, short-wavelength absorption results in a noticeable red color (Copello et al., 2006). For colloidal doped material, the size of the particles has to be shorter than just a visible range, or an opacity glass would then consequence. If one would like a cloudy glass, a variety of chemicals (e.g., SnO2, TiO2, CaF2) may be employed that resulted in a suspension that alters the total index of refraction. Colloidal metals provide a rich red hue, with colloidal gold being employed for the first time in the late 17th century.

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Conversely, a metallic salt like AuCl3 may be introduced to glass and then reduced to metallic Au by heat or chemical means (e.g., using NaBH4). It is worth noting that a red hue will only appear if an agent to inhibit particle aggregation is also introduced. As the mean particle size falls, the visible color shifts toward the blue section of the spectrum (e.g., blue color comes from diameters of 3 × 1020

3 × 1019 – 3 × 1020

1 – 10–3 m

Larger than 1 m

800 nm – 400 nm

10–3 m – 800 nm

< 10–12 m

10–11 m – 10–12 m

Wavelength

10–8 m – 10–11 800 nm – 10–8 m m

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Effect and information

Energy, E (kJ/ mol)

Region

Rotation

Nuclear and transitions

Outer shell electron

Vibration

Bond breaking and ionization

Electron excitation

–

Nuclear

0.001 < E < 0.12

E < 0.001

150 < E