Glass (eBook)

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Jürn W. P. Schmelzer, University of Rostock, Germany.

Foreword 5
Preface 15
List of contributing authorst 21
1 Influence of Thermal Prehistory on Crystal Nucleation and Growth in Polymers 23
1.1 Introduction 23
1.2 State of the Art 24
1.2.1 Dependence of the Properties of Glass-forming Melts on Melt History 24
1.2.2 Polymer Crystallization 28
1.2.3 Differential Fast Scanning Calorimetry 31
1.3 Experimental 36
1.3.1 Samples 36
1.3.2 Suppression of Homogeneous Nucleation at Fast Cooling 38
1.3.3 Non-isothermal Ordering Kinetics 50
1.3.4 Isothermal Ordering Kinetics 58
1.3.5 Identification of Different Nuclei Populations 70
1.3.6 Enthalpy Relaxation and Crystal Nucleation in the Glassy State 74
1.3.7 Summary of Experimental Results and Conclusions 94
1.4 Illumination of the Nucleation and Growth Mechanism 96
1.4.1 Low-temperature Endotherms and Homogeneous Nucleation 96
1.4.2 Some Brief Theoretical Considerations 100
1.5 Conclusions and Outlook 102
2 Early Stages of Crystal Formation in Glass-forming Metallic Alloys 117
2.1 Introduction 117
2.2 Marginal Glass-formers 120
2.2.1 Nucleation versus Growth Control 120
2.2.2 Processing Pathway Modifications 123
2.2.3 Nucleation and Growth Kinetics 127
2.2.4 Characterization of the Amorphous Phase 131
2.2.5 Nanocrystal Formation at Temperatures Well Below Tg 137
2.3 Deformation-induced Nanocrystal Formation 146
2.4 Bulk Metallic Glasses 149
2.5 Conclusions and Hypotheses 153
3 Crystalline and Amorphous Modifications of Silica: Structure, Thermodynamic Properties, Solubility, and Synthesis 159
3.1 Introduction 159
3.2 Properties of Silica Modifications: Literature Search 162
3.2.1 Classical SiO2-literature 163
3.2.2 Original Literature Sources on the Different Silica Modifications 163
3.2.3 Internet Search 164
3.3 Phase Diagram of SiO2 164
3.3.1 Fenner’s Classical Diagram 164
3.3.2 Flörke’s Diagram 165
3.3.3 Contemporary (p - T )-phase Diagrams of SiO2 166
3.4 Modifications of SiO2 and Their Synthesis 170
3.4.1 Mineralogical Characteristics of the SiO2-modifications 170
3.4.2 Synthesis of Quartz 170
3.4.3 Synthesis and Stabilization of ß -cristobalite 173
3.4.4 Synthesis of Keatite: Classical Aspects 181
3.4.5 Synthesis of Coesite 182
3.4.6 Stishovite: Synthesis and Thermal Stability 182
3.4.7 Synthesis of Amorphous Modifications of Silica 185
3.5 Structure and Thermodynamic Properties of the SiO2-modifications 186
3.6 Solubility of the Different SiO2-modifications 192
3.6.1 General Thermodynamic Dependencies 192
3.6.2 Solubility Diagram of SiO2. Ostwald’s Rule of Stages 197
3.6.3 Solubility of SiO2: Size Effects 203
3.6.4 Different SiO2-modifications at Hydrothermal Conditions: Technological Aspects 205
3.7 Resources of the Silica Modifications 208
3.7.1 Mineral Resources of Quartz 208
3.7.2 Plant Resources of Silica 209
3.7.3 Industrial Waste as Sources of Silica 210
3.7.4 Coesite and Stishovite as Impactite Remnants 210
3.8 Some Particularly Interesting Properties of Silica 211
3.9 General Discussion: Technical Perspectives 212
4 The Main Silica Phases and Some of Their Properties 219
4.1 Introduction 219
4.2 Specific Properties of Silica Resulting from the Electronic Structure of Silicon 220
4.2.1 Specific Properties of Silica Compounds and Differences as Compared to Chemical Analogs: Silicon and Carbon 220
4.2.2 Electron Structure of the Silicon Atom and its Interaction with Oxygen 223
4.2.3 Consequences of p-Bonding in Silica 224
4.2.4 Increase in Silicon Coordination Number as a Result of s-p-d-hybridization 225
4.2.5 Implication of s-p-d-hybridization for Chemical Reactions and Physical Transformations of Silica 227
4.3 Phases of Silica and Their Properties 229
4.3.1 Dense Octahedral Silicas: High Pressure Phases 231
4.3.2 Clathrasils: Friable Silica Phases 232
4.3.3 Exception: Fibrous Silica 233
4.3.4 Proper Silicas 233
4.3.5 Main Crystalline Tetrahedral Silicas 235
4.3.6 Amorphous Silica 245
4.3.7 Polyamorphism 247
4.4 Quartz and Some of Its Properties 250
4.4.1 Enantiomorphism of Quartz 250
4.4.2 Twins (Zwillinge) in Quartz 251
4.4.3 Anisotropy of Quartz 254
4.4.4 Thermal Expansion of Quartz 255
4.4.5 High-Low or (a - ß )-Transformation in Quartz 263
4.4.6 Pressure-induced Amorphization of Crystalline Silica 267
4.5 Hydrothermal Synthesis of Quartz 267
4.5.1 Brief History 268
4.5.2 Temperature Drop Method 269
4.5.3 Main Problems of Hydrothermal Synthesis of Quartz 272
4.6 Concluding Remarks 283
4.7 Appendix: The Crystal Skulls 283
5 Chemical Structure of Oxide Glasses: A Concept for Establishing Structure–Property Relationships 291
5.1 Introduction 291
5.2 Structural Models 292
5.3 Thermodynamic Approach 296
5.4 Concept of Chemical Structure 299
5.5 Short-range Order 303
5.5.1 Na2O–B2O3 Glasses 303
5.5.2 Li2O–B2O3 Glasses andMelts 305
5.5.3 Na2O–SiO2 Glasses 309
5.5.4 Na2O–B2O3–SiO2 Glasses 311
5.6 Intermediate-Range Order 311
5.7 Structure–Property Relationships 315
5.8 Summary and Conclusions 318
6 Bubbles in Silica Melts: Formation, Evolution, and Methods of Removal 323
Part I: Experimental Data and Basic Mechanisms 323
6.1 Introduction 323
6.2 Sources of Bubbles in Silica Melt and Glass 324
6.2.1 Brief Account of the Technology of Silica Glass Production 324
6.2.2 Raw Materials as a Source of Bubbles 325
6.2.3 Furnace Atmosphere as a Source of Bubbles 327
6.2.4 Interaction of Heaters and Form-shaping Equipment with the Melt as Source of Bubbles 330
6.2.5 Concentrations of Impurities, Including Dissolved Gases, in Commercial Silica Glasses 330
6.2.6 Experimental Study of Formation and Evolution of Bubbles in Silica Melts 331
6.3 Physico-chemical Properties of Silica Melts Influencing the Formation and Evolution of Gas Bubbles 334
6.3.1 Surface Tension 334
6.3.2 Density 334
6.3.3 Viscosity 335
6.3.4 Solubility and Diffusion of Gases 337
6.4 Summary to Part I 346
Part II: Theoretical Analysis and Computer Simulation of the Process 347
6.5 Introduction to Part II 347
6.5.1 Main Stages of Fusion of Powdered Silica under Heating and Evolution of Bubble Structure 347
6.5.2 Selection of Parameters for the Temperature Dependence Equations that describe the Properties of the Silica Melt Affecting the Kinetics of the Process 348
6.6 Micro-rheological Model and Computer Simulation of the Process 349
6.6.1 The Micro-rheological Model of Powder Sintering and Structuring of a Porous Body 350
6.6.2 Influence of Some Technological Factors on Formation of Bubble Structure under Heating of Powdered Silica Glass: Computer Simulation of the Process 357
6.7 Summary to Part II 365
Part III: Mathematical Modeling and Computer Simulation of the Behavior of Gas-Filled Bubbles in Silica Melts 367
6.8 Introduction 367
6.9 Behavior of Isolated Bubbles 369
6.10 Behavior of Solitary Gas-filled Bubbles under Mass Exchange with the Melt 370
6.11 Two-phase Approach to the Description of Mono-disperse Ensembles of Bubbles 373
6.12 Two-phase Approach to the Description of Poly-disperse Ensembles of Bubbles 378
6.13 Diffusion of the Dissolved Gas in the Melt 382
6.14 Relative Motion of Bubbles in the Melt: Modification of the Mathematical Model 386
6.15 Flow of the Melt Governed by the Motion of the Bubbles: Complete System of Equations for Modeling of the Behavior of Gas-filled Bubble Ensembles in the Melt 391
6.16 Summary to Part III 394
7 Regularities and Peculiarities in the Crystallization Kinetics of Silica Glass 399
7.1 Introduction 399
7.2 Literature Review 403
7.3 Development of Experimental Techniques 413
7.4 Basic Phenomenological Features of the Crystallization Processes 416
7.5 Influence of the Degree of Silica Reduction 420
7.6 Influence of Concentration of “Structural Water” 424
7.7 Influence of the Degree of Fusion Penetration of Quartz or Cristobalite Particles on Crystallization of Quartz Glasses 427
7.8 Influence of Surface Contamination on Crystallization Kinetics 430
7.9 Influence of the Composition of the Gas Medium on Crystallization of Quartz Glass 433
7.9.1 Introductory Comments 433
7.9.2 On Crystallization in Dry Gas Media 433
7.9.3 Experiments on Crystallization in an Atmosphere Containing Water Vapor 435
7.9.4 Crystallization of Quartz Glass in the Atmosphere of Gases in Equilibrium with the Melt 436
7.10 Influence of the Drawing Process on the Crystallization Kinetics of Tubes of Quartz Glasses 439
7.11 Summary of Results and Discussion 444
7.11.1 Introductory Remarks 444
7.11.2 Influence of Surface Reactions on Crystallization 445
7.11.3 Relation Between Crystallization Rate and Viscosity 449
7.12 Conclusions 457
8 Stress-induced Pore Formation and Phase Selection in a Crystallizing Stretched Glass 463
8.1 Introduction 463
8.2 Stress Induced Pore Formation and Phase Selection in a Crystallizing Stretched Glass of Regular Shape 465
8.2.1 The Model 465
8.2.2 Experiments 467
8.2.3 Theoretical Interpretation: Classical Nucleation Theory 474
8.2.4 Theoretical Interpretation: Generalized Gibbs Approach 482
8.3 Sintered Diopside-albite Glass-ceramics Forming Crystallization-induced Porosity 489
8.3.1 Introduction 489
8.3.2 Experimental 490
8.3.3 Results and Discussion 492
9 Crystallization of Undercooled Liquids: Results of Molecular Dynamics Simulations 503
9.1 Introduction 503
9.2 Thermodynamics and Kinetics of Crystal Formation 506
9.3 Description of the Systems under Investigation in the Present Study 509
9.3.1 Models 509
9.3.2 Phase Diagram 510
9.4 Methods of Modeling of Spontaneous Crystallization 511
9.4.1 Mean Life-time Method 511
9.4.2 Mean First-passage Time Method 515
9.4.3 Transition Interface Sampling 518
9.5 Temperature Dependence of the Interfacial Free Energy Density Crystal-liquid for Planar Interfaces 520
9.5.1 Triple Point 520
9.5.2 Melting Line 521
9.6 Kinetics of Crystallization in a cLJ-system 525
9.6.1 Crystallization Parameters 525
9.6.2 Nucleation Rate 529
9.6.3 Comparison of Homogeneous Nucleation Theory with Computer Simulation 530
9.6.4 Nucleation in the Region Below the Endpoint of the Melting Line 531
9.7 Kinetics of Crystallization in the mLJ-system and Free Energy of the Clusters of the Crystalline State 534
9.7.1 Pressure Dependence of the Nucleation Rate 534
9.7.2 Temperature Dependence of the Nucleation Rate 535
9.8 Discussion and Conclusions 539
10 Crystal Nucleation and Growth in Glass-forming Systems: Some New Results and Open Problems 543
10.1 Introduction 544
10.2 Consequences of Stochastic Structural Fluctuations in Ultraviscous Melts 549
10.2.1 Structure Fluctuations, Nucleation and Distribution of Relaxation Times 549
10.2.2 Structure Fluctuations and the Notion of Disordered Cluster Formation 550
10.3 A Case Study: Crystallization Kinetics of a Typical Metal Alloy Melt 557
10.3.1 General Considerations 557
10.3.2 One Experimental Example 559
10.3.3 Theoretical Interpretation in Terms of the KJMA-approach 562
10.3.4 Crystallization on Rate Heating 565
10.3.5 Differences Between Isothermal and Rate-heating Crystallization 568
10.3.6 Origin of the Second Peak for Crystallization on Rate-heating 570
10.4 Thermal Effects of Crystallization on Its Kinetics 572
10.4.1 General Remarks 572
10.4.2 Rayleigh–Bénard Convection Effects 573
10.4.3 Marangoni or Thermo-capillarity Convection Effect 575
10.5 Classical and Generalized Gibbs’ Approaches to Cluster Formation and Growth 576
10.5.1 Basic Ideas 576
10.5.2 Application to Nucleation 578
10.5.3 Application to Cluster Growth Processes 584
10.5.4 Thermodynamics versus Kinetics: Ridge Crossing 585
10.6 Specific Interfacial Energy and the Skapski–Turnbull Relation 590
10.6.1 General Approach to the Determination of the Specific Interfacial Energy: Taylor Expansion 590
10.6.2 Stefan’s Rule and Skapski–Turnbull Relation: Some Interpretation and Extension to Thermodynamic Non-equilibrium States 592
10.7 Dependence of Crystal Nucleation and Growth Processes on Pre-history 595
10.7.1 Introductory Comments 595
10.7.2 Kinetic Criteria for Glass-formation 596
10.7.3 On the Dependence of the State of the Melt on Cooling and Heating Rates and Its Relevance for Crystal Nucleus Formation and Growth 600
10.8 Conclusions 601
Index 609