Structure, Dynamics, and Properties of Silicate Melts

by Stebbins, Jonathan F.; Mcmillan, Paul F.; Dingwell, Donald B.

• ISBN13: 9780939950393
• ISBN10: 0939950391
• Format: Paperback
• Copyright: 1995-11-01
• Publisher: De Gruyter

Table of Contents

Foreword	iii
Editors' Preface	iii
Structural Relaxation and the Glass Transition
C. T. Moynihan
Introduction: The Nature of Structural Relaxation	1	(2)
Phenomenology of Structural Relaxation	3	(7)
Isothermal relaxation	3	(2)
Relaxation during cooling and heating	5	(3)
Dependence of Tg on cooling and heating rate	8	(2)
Kinetics of Structural Relaxation	10	(4)
Isothermal relaxation	10	(2)
Relaxation during cooling and heating	12	(2)
Correlations between Structural Relaxation and Shear Viscosity	14	(3)
Conclusions	17	(1)
References	18	(3)
Relaxation in Silicate Melts: Some Applications
D. B. Dingwell
Introduction	21	(1)
Fundamentals	21	(14)
Phenomenology and significance of the glass transition	21	(4)
Experimental timescales and relaxation times	25	(2)
Volume versus enthalpy relaxation	27	(1)
Volume versus shear relaxation	28	(6)
Secondary relaxations	34	(1)
Applications	35	(27)
Relaxation geospeedometry	35	(4)
Equations of state: liquid expansivity and volume	39	(8)
Relaxation and rheology	47	(3)
Dissipation and failure	50	(1)
Flow birefringence	51	(1)
Isostructural viscosity	51	(2)
Relaxation of fluid inclusions in melts	53	(1)
Determination of Tg of fluid-saturated melts	53	(2)
Viscosity and fragility of hydrous melts	55	(1)
Expansivity of hydrous melts	56	(1)
Water speciation	57	(3)
Relaxation timescales of hydrous species	60	(2)
Outlook	62	(1)
Acknowledgments	62	(1)
References	63	(4)
Rheology and Configurational Entropy of Silicate Melts
P. Richet
Y. Bottinga
Introduction	67	(2)
Viscosity and Relaxation Times	69	(3)
Shear viscosity	69	(1)
Maxwell model	70	(1)
Volume viscosity	71	(1)
Elongational viscosity	72	(1)
Configurational Entropy	72	(4)
Glass transition	72	(1)
Configurational heat capacity	73	(2)
Calorimetric determination of the configurational entropy	75	(1)
Viscosity and Configurational Entropy	76	(12)
Adams-Gibbs theory	76	(1)
Temperature dependence of the viscosity	77	(2)
Viscosity and structural relaxation	79	(2)
Composition dependence of the viscosity	81	(1)
Pressure dependence of the viscosity	82	(2)
Density fluctuations	84	(2)
Newtonian vs. non-Newtonian viscosity	86	(2)
Epilogue	88	(1)
Acknowledgments	89	(1)
References	89	(6)
Viscoelasticity
S. L. Webb
D. B. Dingwell
Introduction	95	(7)
Viscoelasticity	102	(1)
Time- versus frequency-domain measurements	103	(1)
Shear Rheology	103	(8)
Forced torsion	103	(1)
Thermorheological simplicity	104	(4)
Ultrasonics	108	(3)
Shear viscosity	111	(1)
Volume Rheology	111	(3)
Anelasticity	112	(2)
Relaxed Compressibility of Silicate Melts	114	(2)
Elasticity systematics	114	(1)
Iso-structural melts	114	(2)
Outlook	116	(1)
References	117	(4)
Energetics of Silicate Melts
A. Navrotsky
Why Study Energetics?	121	(1)
Methods of Studying Energetics	121	(3)
Factors Affecting Melt Energetics	124	(5)
Major acid-base interactions and polymerization equilibria	124	(2)
Interactions in geologically relevant silicate melts	126	(1)
Charge coupled substitutions	127	(1)
Speciation, clustering, and phase separation	128	(1)
Mixed alkali and mixed cation effects	129	(1)
Applications to Melts of Geologic Composition	129	(10)
Heat capacities and heats of fusion	129	(4)
Heats of mixing of major components	133	(1)
Application of the two-lattice model to entropies of mixing in silicate melts	134	(1)
Energetics of minor components---particularly TiO2	135	(4)
Conclusions	139	(1)
Acknowledgments	140	(1)
References	140	(5)
Thermodynamic Mixing Properties and The Structure of Silicate Melts
P. C. Hess
Introduction	145	(2)
Crystal Chemistry of Simple Silicates	147	(2)
Enthalpies of Formation of Simple Silicates	149	(5)
Enthalpic Electronegativities	154	(2)
Enthalpy of Simple ``Mineral'' Melts	156	(4)
Analysis of Phase Diagrams	160	(12)
Cristobalite-tridymite liquidi	160	(1)
Cotectics and the activities of melt species	161	(2)
Analysis of cotectic shifts-concept of neutral species	163	(3)
Aluminosilicate systems	166	(2)
Rutile saturation surface	168	(4)
Other network-forming species	172	(1)
Critical Melts	172	(4)
Redox Equilibria	176	(2)
Discussion	178	(2)
Acknowledgments	180	(1)
Appendix	180	(7)
Free energy of mixing	180	(5)
Entropy of mixing	185	(2)
References	187	(4)
Dynamics and Structure of Silicate and Oxide Melts: Nuclear Magnetic Resonance Studies
J. F. Stebbins
Introduction	191	(2)
Other sources of background information on NMR	192	(1)
Basic NMR Concepts	193	(15)
Quadrupolar nuclides	195	(1)
Dipole-dipole interactions	196	(1)
Motional averaging	197	(2)
MAS, DOR, DAS: high resolution spectroscopy of solids	199	(1)
Chemical exchange	200	(1)
Two-dimensional exchange experiments	201	(1)
Structural effects on chemical shifts	202	(3)
Spin-lattice relaxation	205	(3)
Experimental Approaches to NMR of Oxide Melts	208	(2)
Application of NMR to Glass Structure	210	(11)
Silicon sites in glasses: Q species and thermodynamic models	210	(3)
Five- and six-coordinated silicon	213	(1)
Oxygen sites	214	(1)
Aluminum coordination	214	(2)
Alkali and alkaline earth cations	216	(1)
Boron coordination	216	(1)
Phosphorous in phosphate glasses	216	(1)
Fictive temperature studies: the effect of temperature on melt structure	217	(1)
Speciation in silicate glasses	217	(1)
Aluminum coordination: changes with Tf	218	(1)
Boron coordination: changes with Tf	218	(1)
The extent of ordering in silicate glasses	219	(1)
Intermediate range order	220	(1)
Orientational disorder	221	(1)
Applications of NMR to Oxide Melts	221	(17)
Chemical exchange in melts: silicate species and viscous flow	221	(2)
Chemical exchange in melts: oxygen, boron and phosphate species	223	(6)
Spin-lattice relaxation and dynamics in melts	229	(1)
Silicon	229	(1)
Aluminum peak widths, relaxation and dynamics	230	(1)
Alkali and alkaline earth cation diffusion	231	(1)
Boron in borate melts	232	(1)
Average local structure in melts	232	(1)
Effects of temperature and melting on structure	233	(3)
Compositional effects on melt structure	236	(2)
Conclusions	238	(1)
Acknowledgments	239	(1)
References	239	(8)
Vibrational Spectroscopy of Silicate Liquids
P. F. McMillan
G. H. Wolf
Introduction	247	(8)
``Liquids'' versus ``glasses''	249	(4)
NMR ``versus'' vibrational spectroscopy	253	(2)
Theoretical Background	255	(11)
Interaction with light: selection rules	255	(4)
Frequency shifts with temperature	259	(1)
Infrared and Raman intensities	260	(3)
Linewidths and lineshapes	263	(3)
Experimental Vibrational Spectroscopy at High Temperatures	266	(7)
Infrared reflection and emission studies	266	(2)
Raman scattering	268	(5)
Vibrational Studies of Aluminosilicate Liquids and Glasses	273	(33)
SiO2	273	(10)
Alkali and alkaline earth silicates	283	(11)
Aluminosilicates along the ``charge-balanced'' SiO2-MAlO2 or SiO2-MAl2O4 joins	294	(11)
Haplobasaltic and other aluminosilicate compositions	305	(1)
Other components	306	(1)
Conclusion	306	(1)
Acknowledgments	307	(1)
References	308	(9)
X-ray Scattering and X-ray Spectroscopy Studies of Silicate Melts
G. E. Brown, Jr.
F. Garges
G. Calas
Introduction	317	(2)
Historical Perspectives	319	(5)
The crystallite and random-network models	319	(2)
Modern studies of glass/melt structure	321	(3)
X-ray Scattering Studies of Silicate Glasses and Melts	324	(24)
Scattered x-ray intensity and radial distribution functions	324	(4)
Quasi-crystalline models of glass/melt structure	328	(2)
Radial distribution function of silica glass	330	(3)
Radial distribution functions of framework aluminosilicate glasses	333	(4)
Experimental approaches to high-temperature X-ray scattering studies of silicate melts	337	(2)
X-ray scattering results for silicate melts	339	(1)
SiO2 and Al2O3 melts	339	(1)
Alkali silicate melts	340	(3)
Alkaline-earth-silicate melts	343	(2)
Iron-silicate melts	345	(2)
Feldspar-composition melts	347	(1)
X-ray Absorption Spectroscopy	348	(34)
Basic principles	348	(2)
Pre-edge region	350	(1)
XANES region	351	(1)
EXAFS region	352	(1)
The harmonic approximation	353	(1)
Anharmonicity	354	(1)
Effective pair-potential method	354	(2)
Cumulant expansion method	356	(1)
Farges-Brown empirical model	357	(1)
Relationship of anharmonicity to bond thermal expansion coefficients	358	(1)
Relationship of anharmonicity to Pauling bond valence	358	(1)
Prediction of anharmonicity in crystals and melts	359	(1)
Model-independent measure of the effective pair-potentials and their g(R) functions	359	(2)
High-temperature XAS experimental methods	361	(1)
Transmission mode	361	(2)
Fluorescence mode	363	(1)
High-temperature XAS results for cations in silicate melts	364	(1)
Highly charged cations	364	(1)
Titanium (IV)	364	(4)
Germanium (IV)	368	(1)
Zirconium (IV)	369	(1)
Molybdenum (VI)	370	(1)
Thorium (IV)	371	(1)
Uranium (VI)	371	(1)
Divalent cations	372	(1)
Iron (II)	372	(3)
Nickel (II)	375	(1)
Zinc (II)	376	(1)
Coordination chemistry of cations in silicate melts: an XAFS perspective	377	(1)
Network-former and modifier roles of cations in silicate melts	377	(1)
The coordination environment of Mg in silicate glasses and melts	378	(1)
Coordination changes above Tg	379	(1)
Implications of XAFS- derived coordination numbers for Fe(II) and Ni(II) for cation partitioning between silicate melts and crystals	379	(3)
Models of Medium-range Order in Silicate Glasses and Melts	382	(5)
Bond valence models of medium-range order in silicate melts	382	(3)
Modified random network model and percolation domains in silicate glasses and melts	385	(2)
Changes in medium-range order caused by nucleation in silicate glasses and melts	387	(1)
Summary of Average M- O Distances and Cation Coordination Numbers in Silicate Glasses and Melts	387	(11)
Conclusions and Future Prospects	398	(2)
Acknowledgments	400	(1)
References	401	(10)
Diffusion in Silicate Melts
S. Chakraborty
Introduction	411	(1)
Historical Background and Present Context	411	(2)
Scope of the Chapter and Some Conventions	413	(2)
Silicate Melts versus Aqueous Solutions	415	(1)
What is Diffusion?	415	(1)
Diffusion of One Kind of Particle in a Melt	416	(7)
Fick's first law and some of its consequences	416	(1)
Fick's second law	417	(2)
Reference frames and units	419	(2)
Limitations to Fick's law and non-Fickian diffusion	421	(1)
Different kinds of diffusion coefficients---Self and tracer diffusion coefficients	422	(1)
Diffusion of Two Components in a Melt	423	(5)
Chemical diffusion coefficients and diffusive coupling	423	(1)
Some characteristics of chemical diffusion coefficients	424	(1)
Relationship between chemical and tracer diffusion coefficients	425	(1)
Thermodynamic factor	426	(1)
Thermodynamic formulation of diffusion	427	(1)
Diffusion in a Multicomponent Melt	428	(11)
Fick-Onsager relations	428	(1)
Some important characteristics of the L and D matrices	429	(2)
Domain of validity of Fick-Onsager relation	431	(1)
Models relating tracer to chemical diffusion coefficients in multicomponent systems	432	(1)
Effective binary diffusion coefficients and multicomponent D matrices	433	(1)
Diffusive coupling and uphill diffusion	434	(3)
Diffusion paths	437	(2)
Relation between Diffusion and Other Properties	439	(21)
Diffusion, relaxation and glass transition	439	(1)
The glass transition and some related concepts	439	(2)
Glass transition and measurement of diffusion coefficients	441	(2)
Effect of glass transition on diffusion data	443	(1)
Unified model for ionic transport above and below the glass transition temperature	444	(2)
Diffusion and melt structure	446	(1)
Relation between structure and diffusion in a glass	447	(1)
Anderson and Stuart (1954) model	448	(1)
Weak electrolyte model	448	(1)
Modified random-network (MRN) transport model	448	(1)
Jump relaxation model	448	(1)
Site mismatch model	449	(2)
Relation between structure and diffusion in a liquid	451	(2)
Diffusion and electrical properties	453	(2)
Diffusion and viscosity	455	(2)
Diffusion and thermodynamic mixing	457	(1)
Use of exact relationships	457	(1)
Dilute constituents in multicomponent systems	457	(1)
Major components in multicomponent systems	457	(1)
Use of empirical observations	458	(1)
Models based on continuous partitioning of elements	458	(1)
Zero flux planes (ZFP)	459	(1)
Relation of diffusion to spectroscopic data	459	(1)
Empirical Methods	460	(5)
Methods to predict elemental diffusion rates	460	(1)
Size-charge correlations	460	(1)
Compensation law	461	(1)
Methods to predict chemical diffusion rates	462	(1)
Transient two-liquid partitioning	462	(1)
Compensation law	463	(1)
Methods to predict chemical diffusion rates	464	(1)
Transient two-liquid partitioning	464	(1)
Modified effective binary model	465	(1)
Experimental Methods	465	(13)
Macroscopic measurements	466	(1)
Problems of handling melts and differences between experiments on ``granites'' vs. ``basalts''	466	(1)
The diffusion anneal	467	(1)
After the anneal---measurement of concentration profiles	468	(1)
Fitting a model to measured profiles---tracer and binary diffusion, constant diffusion coefficients	469	(1)
Fitting a model to measured profiles: chemical diffusion, non-constant diffusion coefficients	470	(2)
Fitting a model to measured profiles---multicomponent diffusion	472	(1)
Spectroscopic methods	473	(1)
Nuclear spectroscopic techniques	474	(1)
Nuclear Magnetic Resonance (NMR)	474	(2)
Vibrational spectroscopic methods	476	(1)
Other methods	476	(1)
Uncertainties in diffusion data	477	(1)
Microscopic Aspects of Diffusion in Silicate Melts	478	(7)
Random walk in amorphous medium	478	(2)
Correlation factors	480	(1)
Relationship of L-matrix to microscopic motion	481	(2)
Computer models---molecular dynamics, Monte Carlo, etc	483	(2)
Diffusion Data in Silicate Melts	485	(10)
Effect of composition on diffusion	486	(1)
Diffusion of alkali ions	486	(1)
Diffusion of network modifiers other than alkalies	486	(1)
Diffusion of network forming cations	487	(1)
Diffusion of anions	487	(1)
Chemical diffusion coefficients	488	(1)
Temperature dependence of diffusion coeficients	489	(1)
Pressure dependence of diffusion coefficients	490	(1)
Pressure dependence for network formers	490	(4)
Pressure dependence for network modifiers	494	(1)
Applications	495	(1)
Acknowledgments	496	(1)
References	497	(8)
Pressure Effects on Silicate Melt Structure and Properties
G. H. Wolf
P. F. McMillan
Introduction	505	(1)
General Highlights	506	(4)
Physical Properties	510	(4)
Structural Properties	514	(38)
Fully polymerized systems	514	(1)
Silica	514	(8)
Germania	522	(3)
``Charge-balanced'' aluminosilicates	525	(3)
Depolymerized silicate systems	528	(1)
Binary alkali silicates	529	(12)
Alkali aluminosilicate systems	541	(4)
Alkaline earth metasilicates	545	(3)
Alkaline earth orthosilicates	548	(4)
Acknowledgments	552	(1)
References	553	(10)
Computer Simulations of Silicate Melts
P. H. Poole
P. F. McMillan
G. H. Wolf
Introduction	563	(2)
Modelling and Measurement	565	(24)
The basic problem	566	(1)
The Monte Carlo method	567	(1)
The molecular dynamics method	568	(3)
``The Devil is in the details...''	571	(1)
Initial conditions	571	(1)
System size and periodic boundary conditions	571	(2)
Constraints and ensembles	573	(2)
Interaction potentials	575	(1)
General features	575	(3)
Long-range interactions	578	(1)
Potentials for silica and silicates	579	(3)
Making ``measurements''	582	(2)
Static properties	584	(2)
Dynamics	586	(3)
Simulations of Silicate Liquids	589	(17)
Mostly SiO2	589	(1)
Structure	589	(1)
Vibrational spectrum	590	(1)
Expanded silica	591	(1)
Phase relations	592	(1)
Diffusion coefficients and mechanism	593	(1)
Diffusion maximum in highly polymerized silicates at high pressure	594	(1)
Silicon coordination at high pressure	595	(1)
Other silicate melt studies	596	(1)
Overview	596	(2)
Structure and properties of binary silicates	598	(1)
Alkali ion mobility	598	(1)
Diffusion of network-forming ions	599	(2)
Al and Si coordination in high temperature melts	601	(3)
The effect of pressure on Si and Al coordination	604	(1)
Mantle melts	605	(1)
Conclusions	606	(1)
Acknowledgments	607	(1)
References	607