Physics of Disordered Materials

This volume and its two companion volumes, entitled Tetrahedrally-Bonded Amorphous Semiconductors and Localization and Metal-Insulator Transitions, are our way of paying special tribute to Sir Nevill Mott and to express our heartfelt wishes to him on the occasion of his eightieth birthday. Sir Nevill has set the highest standards as a physicist, teacher, and scientific leader. Our feelings for him include not only the respect and admiration due a great scientist, but also a deep affection for a great human being, who possesses a rare combination of outstanding personal qualities. We thank him for enriching our lives, and we shall forever carry cherished memories of this noble man. Scientists best express their thanks by contributing their thoughts and observations to a Festschrift. This one honoring Sir Nevill fills three volumes, with literally hundreds of authors meeting a strict deadline. The fact that contributions poured in from all parts of the world attests to the international cohesion of our scientific community. It is a tribute to Sir Nevill's stand for peace and understanding, transcending national borders. The editors wish to express their gratitude to Ghazaleh Koefod for her diligence and expertise in deciphering and typing many of the papers, as well as helping in numerous other ways. The blame for the errors that remain belongs to the editors.

One: General Aspects.- The Inextricably Entangled Skein.- Random and Nonrandom Structures in Higher Dimensions.- Predicting The Structure of Solids.- Chemistry and Structure in Amorphous Materials: The Shapes of Things to Come.- Rigidity Percolation.- A New Approach to the Glass Transition.- Two: Elements of Disorder.- "Phase Transitions" in Disordered Solids.- Random Packing of Structural Units and the First Sharp Diffraction Peak in Glasses.- The Application of the Percus-Yevick Approximation to Calculate the Density Profile and Pair Correlation Function of a Fluid with Density Inhomogeneities.- Order, Frustration and Space Curvature.- Computer-Assisted Modelling of Amorphous Solids.- Beyond the Gaussian Approximation in EXAFS.- Synchrotron Radiation and the Determination of Atomic Arrangements in Amorphous Materials.- A Model for Predicting the Occurrence of Regular Rings in AX2 Tetrahedral Glasses.- Raman Scattering and Variable Order of Amorphous and Liquid Semiconductors.- Modelling Fe Impurity Centres in AS2S3 Glass Using X-ray Absorption Spectroscopy.- Disproportionation as a Source of Constitutional Disorder and Rearrangement in Non-Crystalline Condensed Systems.- Giant Thickness Contraction and Related Effects in Amorphous Chalcogenides.- Partial Filling of a Fractal Structure by a Wetting Fluid.- Clustering of Defects: Disorder of Non-Stoichiometric Oxides.- Disorder in Polyacetylene Probed by Resonant Raman Scattering.- Disordered Regions in Crystalline Silicon At High Temperatures.- Changes in Entropy of Semiconductor Electron Subsystem on Fusion.- Three: Electronic Structure and Transport.- Fundamental Problems Relating to the Electronic Structure of Amorphous Semiconductors.- Recent Progress in the Theory of Amorphous Semiconductors.- OpticalAbsorption in Amorphous Semiconductors: The Independent Band Model and its Experimental Basis.- Optical Absorption in Amorphous Semiconductors.- Electronic Properties of Liquid and Glassy Alloys.- Effective Masses as a Function of Tempera-ture for Polarons which are Composed of a Mixture of Types.- Bipolarons in Transition Metal Oxides.- A Simple Classical Approach to Mobility in Amorphous Materials.- The Sign of the Hall Effect in Disordered Materials.- The Hall Effect in Low Mobility and Amorphous Solids.- Effect of Long Range Potential Fluctuations 011 the Transport Properties of Disordered Semiconductors.- Magnetoresistance in Amorphous Semiconductors.- Comparative Study of AC Losses and Mechanisms in Amorphous Semiconductors.- Multiple Trapping Model For Dispersive Admittance of Amorphous MIS Structures.- The Electrical Conductivity of Transition Metal Oxide-Based Glasses.- Four: The Nature of Defects.- Evidence that Glassy Chalcogenides are Thermodynamic Defect Semi-conductors.- Structural Transformations in Glassy GeSe2 Induced by Laser Irradiation.- Nuclear Quadrupole Resonance in the Chalcogenide and Pnictide Amorphous Semiconductors.- Are We Beginning to Understand the Vibrational Anomalies of Glasses?.- Bipolarons and Tunneling States.- The Study of Disordered Semiconductors by Compensation.- Photoinduced Optical Absorption in Glassy As2Se3.- Validity of the 'Thermalisation Energy' Concept in the Determination of Localised State Distributions for Amorphous Semiconductors.- Geminate Recombination in Some Amorphous Materials.- Transient Photoconductivity in Insulators at Very High Photocarrier Concentrations.- Spin Effects in Amorphous Semiconductors.- Electron States, Negative-U Centres, in Mobility Gap and Some Features of Atomic Structure in GlassySemiconductors.- Stochastic Self-Oscillations in Low Mobility Semiconductors.- n-Type Conduction in Noncrystalline Chalcogenides.- Electrical and Photoelectric Properties of Modified Chalcogenide Vitreous Semiconductors.- Reversible Radiation-Induced Changes of Properties of Chalcogenide Vitreous Semiconductors.- Below Gap Excitation Spectrum for Optically Induced Paramagnetic States in AS2S3 Glass.- Evidence for Two Tellurium Sites in Dilute Liquid Te-Tl Alloys.- Five: Magnetism and Disorder.- Magnetic Order in Disordered Media.- Evidence for Strong Itinerant Ferro-magnetism in Some Amorphous Alloys.- Amorphous Ant iferromagnetism.- Amorphous Rare-Earth Transition-Metal Alloys.- Six: Further Challenges.- Conceptual Development and Technology: Glass 1955-1980.- Gel-Route for New Glasses, Ceramics and Composites.- Problems of Ovonic Switching.- Electrical Switching and Memory Effects in Thin Amorphous Chalcogenide Films.- Disordered Cermets in Photothermal Solar Energy Conversion: The Optical Properties of Black Molybdenum.- of Companion Volumes:Localization and Metal-Insulator Transitions.- Tetrahedrally-Bonded Amorphous Semiconductors.- Author Index.