Structure, dynamics, and properties of silicate melts / ed. by J.F.Stebbins, P.F.McMillan, D.B.Dingwell. - Washington: Mineralogical Society of America, 1995. - xv, 616 p.: ill. - (Reviews in mineralogy; vol.32). - ISBN 0-939950-39-1; ISSN 0275-0279  Место хранения:   018 | Институт нефтегазовой геологии и геофизики им. А.А.Трофимука | Новосибирск | Библиотека

Оглавление / Contents

Foreword ...................................................... iii Editors' Preface .............................................. iii Chapter 1 STRUCTURAL RELAXATION AND THE GLASS TRANSITION С.Т. Moynihan Introduction: The Nature of Structural Relaxation ............... 1 Phenomenology of Structural Relaxation .......................... 3 Isothermal relaxation ........................................ 3 Relaxation during cooling and heating ........................ 5 Dependence of Tg on cooling and heating rate ................. 8 Kinetics of Structural Relaxation .............................. 10 Isothermal relaxation ....................................... 10 Relaxation during cooling and heating ....................... 12 Correlations between Structural Relaxation and Shear Viscosity ...................................................... 14 Conclusions .................................................... 17 References ..................................................... 18 Chapter 2 RELAXATION IN SILICATE MELTS: SOME APPLICATIONS D.B. Dingwell Introduction ................................................... 21 Fundamentals ................................................... 21 Phenomenology and significance of the glass transition ...... 21 Experimental timescales and relaxation times ................ 25 Volume versus enthalpy relaxation ........................... 27 Volume versus shear relaxation .............................. 28 Secondary relaxations ....................................... 34 Applications ................................................... 35 Relaxation geospeedometry ................................... 35 Equations of state: liquid expansivity and volume ........... 39 Relaxation and rheology ..................................... 47 Dissipation and failure .................................. 50 Flow birefringence ....................................... 51 Isostructural viscosity .................................. 51 Relaxation of fluid inclusions in melts ..................... 53 Determination of To of fluid-saturated melts ............. 53 Viscosity and fragility of hydrous melts ................. 55 Expansivity of hydrous melts ............................. 56 Water speciation ......................................... 57 Relaxation timescales of hydrous species .................... 60 Outlook ........................................................ 62 Acknowledgments ................................................ 62 References ..................................................... 63 Chapter 3 RHEOLOGY AND CONFIGURATIONAL ENTROPY OF SILICATE MELTS P. Richet & Y. Bottinga Introduction ................................................... 67 Viscosity and Relaxation Times ................................. 69 Shear viscosity ............................................. 69 Maxwell model ............................................... 70 Volume viscosity ............................................ 71 Elongational viscosity ...................................... 72 Configurational Entropy ........................................ 72 Glass transition ............................................ 72 Configurational heat capacity ............................... 73 Calorimetric determination of the configurational entropy ... 75 Viscosity and Configurational Entropy .......................... 76 Adams-Gibbs theory .......................................... 76 Temperature dependence of the viscosity ..................... 77 Viscosity and structural relaxation ......................... 79 Composition dependence of the viscosity ..................... 81 Pressure dependence of the viscosity ........................ 82 Density fluctuations ........................................ 84 Newtonian vs. non-Newtonian viscosity ....................... 86 Epilogue ....................................................... 88 Acknowledgments ................................................ 89 References ..................................................... 89 Chapter 4 VISCOELASTICITY S.L. Webb and D.B. Dingwell Introduction ................................................... 95 Viscoelasticity ............................................... 102 Time- versus frequency-domain measurements ................. 103 Shear Rheology ................................................ 103 Forced torsion ............................................. 103 Thermorheological simplicity ............................... 104 Ultrasonics ................................................ 108 Shear viscosity ............................................ 1ll Volume Rheology ............................................... 111 Anelasticity .................................................. 112 Relaxed Compressibility of Silicate Melts ..................... 114 Elasticity systematics ..................................... 114 Iso-structural melts ....................................... 114 Outlook ....................................................... 116 References .................................................... 117 Chapter 5 ENERGETICS OF SILICATE MELTS A. Navrotsky Why Study Energetics? ......................................... 121 Methods of Studying Energetics ................................ 121 Factors Affecting Melt Energetics ............................. 124 Major acid-base interactions and polymerization equilibria ................................................. 124 Interactions in geologically relevant silicate melts ....... 126 Charge coupled substitutions ............................ 127 Speciation, clustering, and phase separation ............ 128 Mixed alkali and mixed cation effects ................... 129 Applications to Melts of Geologic Composition ................. 129 Heat capacities and heats of fusion ........................ 129 Heats of mixing of major components ........................ 133 Application of the two-lattice model to entropies of mixing in silicate melts ................................... 134 Energetics of minor components-particularly Т1О2 ........... 135 Conclusions ................................................... 139 Acknowledgments ............................................... 140 References .................................................... 140 Chapter 6 Thermodynamic Mixing Properties and The Structure of Silicate Melts P.C. Hess Introduction .................................................. 145 Crystal Chemistry of Simple Silicates ......................... 147 Enthalpies of Formation of Simple Silicates ................... 149 Enthalpic Electronegativities ................................. 154 Enthalpy of Simple "Mineral" Melts ............................ 156 Analysis of Phase Diagrams .................................... 160 Cristobalite-tridymite liquidi ............................. 160 Cotectics and the activities of melt species ............... 161 Analysis of cotectic shifts-concept of neutral species ..... 163 Aluminosilicate systems .................................... 166 Rutile saturation surface .................................. 168 Other network-forming species .............................. 172 Critical Melts ................................................ 172 Redox Equilibria .............................................. 176 Discussion .................................................... 178 Acknowledgments ............................................... 180 Appendix ...................................................... 180 Free energy of mixing ...................................... 180 Entropy of mixing .......................................... 185 References .................................................... 187 Chapter 7 Dynamics and Structure of Silicate and Oxide Melts: Nuclear Magnetic Resonance Studies J.F. Stebbins Introduction .................................................. 191 Other sources of background information on NMR ............. 192 Basic NMR Concepts ............................................ 193 Quadrupolar nuclides ....................................... 195 Dipole-dipole interactions ................................. 196 Motional averaging ......................................... 197 MAS, DOR, DAS: high resolution spectroscopy of solids ...... 199 Chemical exchange .......................................... 200 Two-dimensional exchange experiments ....................... 201 Structural effects on chemical shifts ...................... 202 Spin-lattice relaxation .................................... 205 Experimental Approaches to NMR of Oxide Melts ................. 208 Application of NMR to Glass Structure ......................... 210 Silicon sites in glasses: Q species and thermodynamic models ..................................................... 210 Five- and six-coordinated silicon ....................... 213 Oxygen sites ............................................... 214 Aluminum coordination ...................................... 214 Alkali and alkaline earth cations .......................... 216 Boron coordination ......................................... 216 Phosphorous in phosphate glasses ........................... 216 Fictive temperature studies: the effect of temperature on melt structure ............................................. 217 Speciation in silicate glasses .......................... 217 Aluminum coordination: changes with Tf .................. 218 Boron coordination: changes with Tf ..................... 218 The extent of ordering in silicate glasses ................. 219 Intermediate range order ................................ 220 Orientational disorder .................................. 221 Applications of NMR to Oxide Melts ............................ 221 Chemical exchange in melts: silicate species and viscous flow ....................................................... 221 Chemical exchange in melts: oxygen, boron and phosphate species .................................................... 223 Spin-lattice relaxation and dynamics in melts .............. 229 Silicon ................................................. 229 Aluminum peak widths, relaxation and dynamics ........... 230 Alkali and alkaline earth cation diffusion .............. 231 Boron in borate melts ................................... 232 Average local structure in melts ........................... 232 Effects of temperature and melting on structure ......... 233 Compositional effects on melt structure ................. 236 Conclusions ................................................... 238 Acknowledgments ............................................... 239 References .................................................... 239 Chapter 8 Vibrational Spectroscopy of Silicate Liquids P.F. McMillan & G.H. Wolf Introduction .................................................. 247 "Liquids" versus "glasses" ................................. 249 NMR "versus" vibrational spectroscopy ...................... 253 Theoretical Background ........................................ 255 Interaction with light: selection rules .................... 255 Frequency shifts with temperature .......................... 259 Infrared and Raman intensities ............................. 260 Linewidths and lineshapes .................................. 263 Experimental Vibrational Spectroscopy at High Temperatures .... 266 Infrared reflection and emission studies ...................... 266 Raman scattering .............................................. 268 Vibrational Studies of Aluminosilicate Liquids and Glasses .... 273 SiO2 ....................................................... 273 Alkali and alkaline earth silicates ........................ 283 Aluminosilicates along the "charge-balanced" SiO2-MAlO2 or SiO2-MAl2O4 joins ....................................... 294 Haplobasaltic and other aluminosilicate compositions ....... 305 Other components ........................................... 306 Conclusion .................................................... 306 Acknowledgments ............................................... 307 References .................................................... 308 Chapter 9 X-RAY SCATTERING AND X-RAY SPECTROSCOPY STUDIES OF SILICATE MELTS G.E. Brown, Jr., F. Farges & G. Calas Introduction .................................................. 317 Historical Perspectives ....................................... 319 The crystallite and random-network models .................. 319 Modern studies of glass/melt structure ..................... 321 X-ray Scattering Studies of Silicate Glasses and Melts ........ 324 Scattered x-ray intensity and radial distribution functions .................................................. 324 Quasi-crystalline models of glass/melt structure ........... 328 Radial distribution function of silica glass ............... 330 Radial distribution functions of framework aluminosilicate glasses .................................... 333 Experimental approaches to high-temperature X-ray scattering studies of silicate melts ....................... 337 X-ray scattering results for silicate melts ................ 339 SiO2 and Al2O3 melts .................................... 339 Alkali silicate melts ................................... 340 Alkaline-earth-silicate melts ........................... 343 Iron-silicate melts ..................................... 345 Feldspar-composition melts .............................. 347 X-ray Absorption Spectroscopy ................................. 348 Basic principles ........................................... 348 Pre-edge region ......................................... 350 XANES region ............................................ 351 EXAFS region ............................................ 352 The harmonic approximation .............................. 353 Anharmonicity ........................................... 354 Effective pair-potential method ......................... 354 Cumulant expansion method ............................... 356 Farges-Brown empirical model ............................ 357 Relationship of anharmonicity to bond thermal expansion coefficients .................................. 358 Relationship of anharmonicity to Pauling bond valence ... 358 Prediction of anharmonicity in crystals and melts .......... 359 Model-independent measure of the effective pair- potentials and their g(R) functions ........................ 359 High-temperature XAS experimental methods .................. 361 Transmission mode ....................................... 361 Fluorescence mode ....................................... 363 High-temperature XAS results for cations in silicate melts ...................................................... 364 Highly charged cations ..................................... 364 Titanium (IV) ........................................... 364 Germanium (IV) .......................................... 368 Zirconium (IV) .......................................... 369 Molybdenum (VI) ......................................... 370 Thorium (IV) ............................................ 371 Uranium (VI) ............................................ 371 Divalent cations ........................................... 372 Iron (II) ............................................... 372 Nickel (II) ............................................. 375 Zinc (II) ............................................... 376 Coordination chemistry of cations in silicate melts: an XAFS perspective ........................................... 377 Network-former and modifier roles of cations in silicate melts .......................................... 377 The coordination environment of Mg in silicate glasses and melts ....................................... 378 Coordination changes above To ........................... 379 Implications of XAFS- derived coordination numbers for Fe(II) and Ni(II) for cation partitioning between silicate melts and crystals ............................. 379 Models of Medium-range Order in Silicate Glasses and Melts .... 382 Bond valence models of medium-range order in silicate melts ...................................................... 382 Modified random network model and percolation domains in silicate glasses and melts .............................. 385 Changes in medium-range order caused by nucleation in silicate glasses and melts ................................. 387 Summary of Average М- О Distances and Cation Coordination Numbers in Silicate Glasses and Melts ......................... 387 Conclusions and Future Prospects .............................. 398 Acknowledgments ............................................... 400 References .................................................... 401 Chapter 10 Diffusion in Silicate Melts S. Chakraborty Introduction .................................................. 411 Historical Background and Present Context ..................... 411 Scope of the Chapter and Some Conventions ..................... 413 Silicate Melts versus Aqueous Solutions ....................... 415 What is Diffusion? ............................................ 415 I. Diffusion of One Kind of Particle in a Melt ................ 416 Fick's first law and some of its consequences .............. 416 Fick's second law .......................................... 417 Reference frames and units ................................. 419 Limitations to Fick's law and non-Fickian diffusion ........ 421 Different kinds of diffusion coefficients- Self and tracer diffusion coefficients .............................. 422 II. Diffusion of Two Components in a Melt ..................... 423 Chemical diffusion coefficients and diffusive coupling ..... 423 Some characteristics of chemical diffusion coefficients .... 424 Relationship between chemical and tracer diffusion coefficients ............................................... 425 Thermodynamic factor ....................................... 426 Thermodynamic formulation of diffusion ..................... 427 III. Diffusion in a Multicomponent Melt ....................... 428 Fick-Onsager relations ..................................... 428 Some important characteristics of the L and D matrices ..... 429 Domain of validity of Fick-Onsager relation ................ 431 Models relating tracer to chemical diffusion coefficients in multicomponent systems .................................. 432 Effective binary diffusion coefficients and multicomponent D matrices .................................. 433 Diffusive coupling and uphill diffusion .................... 434 Diffusion paths ............................................ 437 IV. Relation between Diffusion and Other Properties ........... 439 Diffusion, relaxation and glass transition ................. 439 The glass transition and some related concepts .......... 439 Glass transition and measurement of diffusion coefficients ............................................ 441 Effect of glass transition on diffusion data ............ 443 Unified model for ionic transport above and below the glass transition temperature ........................ 444 Diffusion and melt structure ............................... 446 Relation between structure and diffusion in a glass ........... 447 Anderson and Stuart (1954) model .............................. 448 Weak electrolyte model ........................................ 448 Modified random-network (MRN) transport model ................. 448 Jump relaxation model ......................................... 448 Site mismatch model ........................................... 449 Relation between structure and diffusion in a liquid .......... 451 Diffusion and electrical properties ........................ 453 Diffusion and viscosity .................................... 455 Diffusion and thermodynamic mixing ......................... 457 Use of exact relationships .............................. 457 Dilute constituents in multicomponent systems ........ 457 Major components in multicomponent systems ........... 457 Use of empirical observations ........................... 458 Models based on continuous partitioning of elements ............................................. 458 Zero flux planes (ZFP) ............................... 459 Relation of diffusion to spectroscopic data ................ 459 V. Empirical Methods .......................................... 460 Methods to predict elemental diffusion rates ............... 460 Size-charge correlations ................................ 460 Compensation law ........................................ 461 Methods to predict chemical diffusion rates ................ 462 Transient two-liquid partitioning ....................... 462 Compensation law ........................................ 463 Methods to predict chemical diffusion rates ................ 464 Transient two-liquid partitioning ....................... 464 Modified effective binary model ......................... 465 VI. Experimental Methods ...................................... 465 Macroscopic measurements ................................... 466 Problems of handling melts and differences between experiments on "granites" vs. "basalts" ................. 466 The diffusion anneal .................................... 467 After the anneal-measurement of concentration profiles ................................................ 468 Fitting a model to measured profiles-tracer and binary diffusion, constant diffusion coefficients ....... 469 Fitting a model to measured profiles: chemical diffusion, non-constant diffusion coefficients .......... 470 Fitting a model to measured profiles-multicomponent diffusion ............................................... 472 Spectroscopic methods ...................................... 473 Nuclear spectroscopic techniques ........................ 474 Nuclear Magnetic Resonance (NMR) ..................... 474 Vibrational spectroscopic methods ....................... 476 Other methods .............................................. 476 Uncertainties in diffusion data ............................ 477 VII. Microscopic Aspects of Diffusion in Silicate Melts ....... 478 Random walk in amorphous medium ............................ 478 Correlation factors ........................................ 480 Relationship of L-matrix to microscopic motion ............. 481 Computer models-molecular dynamics, Monte Carlo, etc ....... 483 VIII. Diffusion Data in Silicate Melts ........................ 485 Effect of composition on diffusion ......................... 486 (1) Diffusion of alkali ions ............................ 486 (2) Diffusion of network modifiers other than alkalies ............................................ 486 (3) Diffusion of network forming cations ................ 487 (4) Diffusion of anions ................................. 487 (5) Chemical diffusion coefficients ..................... 488 Temperature dependence of diffusion coefficients ........... 489 Pressure dependence of diffusion coefficients .............. 490 Pressure dependence for network formers ....................... 490 Pressure dependence for network modifiers ..................... 494 IX. Applications .............................................. 495 Acknowledgments ............................................... 496 References .................................................... 497 Chapter 11 PRESSURE EFFECTS ON SILICATE MELT STRUCTURE AND PROPERTIES G.H. Wolf & P.F. McMillan Introduction .................................................. 505 General Highlights ............................................ 506 Physical Properties ........................................... 510 Structural Properties ......................................... 514 Fully polymerized systems .................................. 514 Silica .................................................. 514 Germania ................................................ 522 "Charge-balanced" aluminosilicates ...................... 525 Depolymerized silicate systems ............................. 528 Binary alkali silicates ................................. 529 Alkali aluminosilicate systems .......................... 541 Alkaline earth metasilicates ............................ 545 Alkaline earth orthosilicates ........................... 548 Acknowledgments ............................................... 552 References .................................................... 553 Chapter 12 Computer Simulations of Silicate Melts P.H. Poole, P.F. McMillan & G.H. Wolf Introduction .................................................. 563 Modelling and Measurement ..................................... 565 The basic problem .......................................... 566 The Monte Carlo method ..................................... 567 The molecular dynamics method .............................. 568 "The Devil is in the details..." ........................... 571 Initial conditions ...................................... 571 System size and periodic boundary conditions ............ 571 Constraints and ensembles ............................... 573 Interaction potentials ..................................... 575 General features ........................................ 575 Long-range interactions ................................. 578 Potentials for silica and silicates ..................... 579 Making "measurements" ...................................... 582 Static properties ....................................... 584 Dynamics ................................................ 586 Simulations of Silicate Liquids ............................... 589 Mostly SiO2 ................................................ 589 Structure ............................................... 589 Vibrational spectrum .................................... 590 Expanded silica ......................................... 591 Phase relations ......................................... 592 Diffusion coefficients and mechanism ....................... 593 Diffusion maximum in highly polymerized silicates at high pressure .............................................. 594 Silicon coordination at high pressure ...................... 595 Other silicate melt studies ................................ 596 Overview ................................................ 596 Structure and properties of binary silicates ............ 598 Alkali ion mobility ..................................... 598 Diffusion of network-forming ions ....................... 599 Al and Si coordination in high temperature melts ........ 601 The effect of pressure on Si and Al coordination ........ 604 Mantle melts ............................................ 605 Conclusions ................................................... 606 Acknowledgments ............................................... 607 References .................................................... 607