Chemical Transport Reactions

ContentsPreface to the English Edition Preface to the German Edition 1. Introduction and Historical Review2. Experimental and Theoretical Principles 2.1 Experimental Techniques 2.1.1 Flow Methods 2.1.2 Gas Motion by Diffusion 2.1.3 Gas Motion by Thermal Convection 2.1.4 Annealing and Temperature Gradients 2.2 The Rate Determining Step in the Transport Process 2.2.1 The Gas Motion 2.2.2 The Reaction Rate 2.2.3 Relationship between Gas Diffusion and Reaction Speed 2.3 Calculation of the Transport Effect of Heterogeneous Equilibria for a Gas Motion between Equilibrium Spaces 2.3.1 Flow Method 2.3.2 Diffusion Methods 2.3.3 Gas Motion through Thermal Convection 2.4 The Transport Effect and the Thermodynamic Quantities of the Transport Reaction 3. The Transport of Solid Substances and Its Special Applications 3.1 Examples of Transportable Solid Substances 3.1.1 Elements, T1¿T2 3.1.2 Elements, T2¿T1 3.1.3 Oxides, T1¿T2 3.1.4 Oxides, T2¿T1 3.1.5 Sulfides, Selenides, and Tellurides; T2¿T1 3.1.6 Halides (T2¿T1) and Oxidehalides (T2¿T1) 3.1.7 Nitrides, Phosphides, Arsenides, and Antimonides 3.1.8 Transport of Other Compounds 3.2 Separation and Purification of Substances by Means of Material Transport. Purity of Transported Material 3.2.1 The Substances A and A' Occur in a Heterogeneous Mixture 3.2.2 The Substances of A and A' to be Separated Form a Homogeneous Solid Phase 3.2.3 Observed Separation Effects 3.2.4 Improvement of the Purification Effect. Addition of Foreign Substances 3.2.5 Introduction of Impurities by Transport 3.3 Transporting Reagents as Mineralizers 3.3.1 Examples of the Mineralization Effect of Transport Reactions 3.3.2 Remarks on the Tridymite Problem 3.3.3 Equalization and Mineralization Effects on Hot Filaments 3.3.4 Particle Size and Mineralization Effect in the Measurement of Heterogeneous Equilibria 3.3.5 Possibilities of Further Development 3.4 Preparation of Single Crystals 85 3.4.1 Small Single Crystals for X-ray Pattern Photographs 3.4.2 Single-Crystal Filaments (Whiskers) 3.4.3 Larger Single Crystals 3.4.4 Oriented Crystal Growth. Epitaxy 3.5 Crystalline Substances with Homogeneous Regions. Mixed Crystals 4. Information on the Reaction Process in the Gas Phase 4.1 Indications of New Gaseous Compounds 4.2 Systems with a Reversible Transport Direction. Critical Decomposition Points 4.2.1 Influence of the Temperature on the Transport Direction 4.2.2 Influence of the Pressure on the Transport Direction 4.2.3 The Critical Decomposition Point 5. Chemical Transport Processes as an Aid in Preparative Chemistry. Combination of Transport Reactions with Other Processes 5.1 Syntheses in Temperature Gradients 5.2 Promotion of Reactions between Solid Substances by Transport Processes 5.2.1 Examples 5.2.2 Variations 6. The Use of Transport Experiments in the Determination of Thermodynamic values 6.1 Determination of Quantities Transported in the Diffusion Tube 6.2 Test of the Reversibility 6.3 Inversion of the Transport Direction. Critical Decomposition Point 6.3.1 Enthalpy of Formation of Carbon Monosulfide 6.3.2 The Thermal Behavior of Silicon Tetraiodide 6.3.3 The Critical Decomposition Point in the Titanium Transport by the Iodide Method 6.3.4 Niobium Deposition and Niobium Carbide Formation from a Niobium Pentachloride Gas Phase References Subject Index Index of Materials Transported and Transporting Reagents