Introduction to Thermoelectricity (eBook)

Preface 6
Acknowledgments 8
Contents 9
1 The Thermoelectric and Related Effects 16
1.1 Introduction 16
1.2 Relations Between the Thermoelectric Coefficients 18
1.3 Effects in a Magnetic Field 20
References 21
2 Theory of Thermoelectric Refrigeration and Generation 22
2.1 The Transport Effects 22
2.2 Thermoelectric Refrigerators and Heat Pumps 23
2.3 Thermoelectric Generators 28
2.4 Multi-Stage Devices 30
2.5 Application of the Thermomagnetic Effects 32
References 36
3 Thermoelectric Properties of Metals and Semiconductors 37
3.1 Transport by Electrons 37
3.2 Metals and Semiconductors 43
3.3 Bipolar Effects 48
3.4 Phonon Conduction 50
3.5 Phonon Drag 53
References 55
4 Optimisation and Selection of Semiconductor Thermoelements 56
4.1 Power Factor 56
4.2 The Materials Parameter, 57
4.3 Mobility and Effective Mass 59
4.4 The Lattice Thermal Conductivity in Pure Crystals 60
4.5 The Effect of Temperature 63
4.6 The Importance of the Energy Gap 64
4.7 Non-Parabolic Bands 66
4.8 Thermomagnetic Materials 68
4.9 Superconductors as Passive Thermoelements 73
References 74
5 Minimising the Thermal Conductivity 76
5.1 Semiconductor Solid Solutions 76
5.2 Phonon Scattering by Point Defects 77
5.3 Boundary Scattering 83
5.4 Scattering of Electrons and Phonons 85
5.5 Fine-Grained Material with Large Unit Cells 87
5.6 Phonon-Glass Electron-Crystal 89
References 90
6 The Improvement of a Specific Material – Bismuth Telluride 92
6.1 Pure Bismuth Telluride 92
6.2 Band Structure of Bismuth Telluride 95
6.3 Diffusion in Bismuth Telluride 99
6.4 Solid Solutions Based on Bismuth Telluride 100
6.5 Practical Developments 103
6.6 Extension of the Temperature Range 106
6.7 Recent Advances 109
References 110
7 Methods for the Production of Materials 111
7.1 General Principles 111
7.2 Growth From the Melt 112
7.3 Sintering 117
7.4 Thick and Thin films 121
References 121
8 Measurement Techniques 124
8.1 General Considerations 124
8.2 Electrical Conductivity 125
8.3 Seebeck Coefficient 129
8.4 Thermal Conductivity 132
8.5 Thermal Diffusivity 137
8.6 The Figure of Merit 139
8.7 Thermomagnetic Measurements 146
References 149
9 Review of Thermoelectric Materials 150
9.1 Bismuth and Bismuth–Antimony 150
9.2 Lead Telluride and Related Compounds 159
9.3 Silicon–Germanium Alloys 162
9.4 Skutterudites and Clathrates 165
9.4.1 Skutterudites 165
9.4.2 Clathrates 167
9.5 Oxides 170
9.6 Other Thermoelectric Materials 171
9.6.1 Zinc Antimonide 171
9.6.2 Half-Heusler Compounds 172
9.6.3 Metal Silicides 173
9.6.4 Boron Carbide 174
References 174
10 Thermoelectric Modules and Their Application 178
10.1 The Modular Concept 178
10.2 Heat Transfer Problems 182
10.3 Electrical Contact Resistance 185
10.4 Applications of the Peltier Effect 187
10.5 Transient Cooling 190
10.6 Seebeck Devices 193
References 199
11 Transverse Devices 201
11.1 Features of Transverse Coolers and Generators 201
11.2 Synthetic Transverse Thermoelements 202
11.3 Materials for Transverse Thermoelements 205
11.4 Alternative Configurations 210
References 211
12 Properties of Nanostructured Materials 212
12.1 Theory of Nanostructures 212
12.2 Thermal Conduction in Low-Dimensional Materials 217
12.3 Observations on Nanostructures 222
12.4 Preparation of Nanostructures 225
References 228
13 Thermionic Energy Conversion 230
13.1 Vacuum Thermoelements 230
13.2 Thermionic Emission in Solids 237
References 241
Bibliography 243
Index 245
Index of Elements, Compounds and Alloys 249