Molten salts are investigated by very diverse techniques and for differ ing purposes, and the results are reported in widely scattered journals. There is a need to keep investigators aware of progress in other specialties and to provide students with source and background material. Advances in Molten Salt Chemistry hopes to fill these needs by providing reviews of recent progress presented, insofar as is reasonable, with enough background material and commentary to be comprehensible to a nonspecialist. We prefer a discussion of underlying principles, to the extent that they are known, and we encourage authors to comment critically on the reliability of data, the utility of models, and the cogency of ideas and theories. We take a broad vie~ of the suitability of topics for inclusion in this series. Both fundamental and technological advances have a place here, as do studies on materials related to molten salts (like liquid silicates, very concentrated aqueous solutions, solutions of salts in liquid metals, and solid electrolytes). We intend this series to serve the needs of those who investigate or use molten salts. We welcome suggestions of topics and suitable authors, as well as comments on the strengths and shortcomings of what is published.

Molten salts are of considerable significance to chemical technology. Applications range from the established ones, such as the production of aluminum, magnesium, sodium and fluorine, to those as yet to be fully exploited, such as molten salt batteries and fuel cells, catalysis, and solar energy. Molten salts are investigated for different purposes by many diverse techniques. There is a need to keep investigators working in different areas, such as metal production, power sources, and glass industry, aware of progress in various specialties, as well as to familiarize new research workers with the fundamental aspects of the broad field of molten salt _ chemistry. This volume constitutes the plenary lectures presented at the NATO Advanced Study Institute on Molten Salt Chemistry, Camerino, Italy, August 3-15, 1986. The fundamentals and several selected applications of molten salt chemistry were addressed. The major fundamental topics covered at this ASI were the structure of melts, thermodynamics of molten salt mixtures, theoretical and experimental studies of transport processes, metal-metal salt solutions, solvent properties of melt systems, acid-base effects in molten salt chemistry, electronic absorption, vibrational, and nuclear magnetic resonance spectroscopy of melt systems, electrochemistry and electroanalytical chemistry in molten salts, and organic chemistry in molten salts. The applied aspects of molten salt chemistry included the chemistry of aluminum production, electrodeposition using molten salts, and molten salt batteries and fuel cells.

The first chapter of this volume deals with computer simulation of molten salt behavior by molecular dynamics calculations. The next four chapters are reviews of experimental work: Chapter 2 deals with the solubility of nonre active gases in molten salts, Chapter 3 with various types of organic reactions in molten tetrachloroaluminates, Chapter 4 with techniques for the study of molten fluorides, and Chapter 5 with the physical and chemical properties of thiocyanate melts. The last chapter is a collection of phase diagrams for binary and ternary fluoride systems. J. B., G. M., G. P. S. v CONTENTS Chapter 1 MOLECULAR DYNAMICS CALCULATIONS ON MOLTEN IONIC SALTS L. V. Woodcock 1. Introduction. . 4 2. Intermolecular Forces in Molten Salts 4 2.1. True and Effective Pair Potentials 2.2. Semiempirical Models 6 3. Computational Techniques 13 3.1. Molecular Dynamics Simulation 13 3.2. The Monte Carlo Method 15 3.3. Electrostatic Summations . . 18 4. Calculation of Physical Properties 23 4.1. Equilibrium Properties . 23 4.2. Transport Coefficients 27 4.3. Spectroscopic Properties 32 5. Applications. . . . . . . . 35 5.1. Studies of Interionic Forces. 35 5.2. Microstructure and Mechanisms 40 5.3. Interpretation of Experimental Observables 50 5.4. Reappraisal of Molten Salt Theories . 64 70 6. Conclusions 7. References. 72 vii Contents viii Chapter 2 GAS SOLUBILITY IN MOLTEN SALTS P. Field 1. Introduction 75 2. Experimental Techniques 78 3. Solution Thermodynamics.