Thermoelectric Power of Metals

ISBN-13: 9781461342700 / Angielski / Miękka / 2011 / 264 str.

J. Blatt

Opis

Thermoelectric and related transport properties of metals have been a source of information and, also, exasperation to physicists for over a century. Perhaps the principal reasons for interest in these phenomena are their sensitivity to composition, structure and external fields and, until fairly recently, the distressing fact that often even gross experimental features such as the sign of the thermopower eluded theoretical understanding. During the past two decades many of the previously perplexing aspects of thermoelectricity have yielded to more sophisticated theoretical treat ment. As a result of this effort and concomitant experimental work using advanced measurement techniques, there is now good reason to believe that thermoelectric phenomena can shed much light on the interactions between electrons and phonons, impurities, and other defects. The last few years have witnessed new and fascinating developments that promise to stimulate new activity in this field. In contrast to the more conventional transport properties, second-and high-order contributions in electron scattering theory appear to play a profound role in thermoelectricity-the controversy surrounding ordinary and "phony" phonon drag is far from resolved; the startlingly large effect of magnetic fields on the thermopower of metals appears to be linked intimately to scattering anisotropy; quantum oscillations of thermopower are orders of magnitude larger than corresponding oscillations of the magnetoresistance; a new approach to thermoelectric studies allows extension of thermopower measurements into the millikelvin region of temperature; finally, the advent of superconducting detection devices permits the precise measurement of extremely small voltages, an essential requirement in this field."

Spis treści

1. Introduction.- 1.1 Seebeck, Peltier, and Thomson Effects.- 1.2 Transport Coefficients and Onsager Relations.- 2. Survey of the Theory of Electronic Conduction in Metals.- 2.1 Electrons in Metals.- 2.1a Free Electron Gas.- 2.1b Energy Bands.- 2.2 Transport Properties.- 2.3 Relaxation Time Anisotropy for Spherical Fermi Surfaces.- 2.4 Thermopower: Isotropic Relaxation Time Approximation.- 2.5 Thermopower: Real Metals.- 2.5a Alkali and Noble Metals.- 2.5b Polyvalent Metals.- 2.6 Phonon Drag.- 2.7 Thermopower of Alloys.- 2.7a Diffusion Thermopower.- 2.7b Phonon Drag.- 3. Techniques in Thermoelectric Measurements.- 3.1 Introduction.- 3.2 Seebeck Effect.- 3.3 Peltier Effect.- 3.4 Thomson Effect: The Absolute Thermopower of Lead.- 3.5 Measurement of Unconventional Thermoelectric Coefficients.- 3.6 Measurement of Temperature and of Small Voltages.- 3.6a Temperature Measurement.- 3.6b Voltage Measurement.- 3.7 Superconducting Devices.- 3.7a Superconducting Modulators.- 3.7b Weak Link and Josephson Junction Devices—SQUIDS and Slugs.- 3.7b1 SQUIDS.- 3.7b2 Slugs.- 4. Phonon Drag.- 4.1 Introduction and General Relations.- 4.2 Sg at High Temperatures.- 4.3 Sg at Low Temperatures.- 4.3a Low-Temperature Phonon Drag in the Alkali Metals.- 4.3b Low-Temperature Phonon Drag in Other Metals.- 4.4 Anisotropy of Relaxation Times and Phonon-Drag Thermopower.- 4.5 Sg at Intermediate Temperatures.- 4.6 Sg of Alloys.- 4.7 Phonon Drag or Phony Phonon Drag?.- 4.7a Pure Metals.- 4.7b Dilute Alloys.- 4.7c Evidence for “Phony Phonon Drag”.- 4.7d Effects of Higher-Order Scattering Processes.- 5. The Thermoelectric Power of Transition Metals.- 5.1 Special Problems in Transition Metals.- 5.1a s- and d-Conduction.- 5.1b Electron-Electron Collisions.- 5.1c Magnetic Effects: Collective Electrons and Isolated Spins.- 5.1d Magnetic Effects: Magnons and Paramagnons.- 5.1e Magnetic Effects: Spin Mixing.- 5.1f Magnetic Effects: The Curie and Néel Temperatures.- 5.2 The Diffusion Thermopower of Transition Metals.- 5.2a Phonons and Impurities.- 5.2b Electron-Electron Scattering.- 5.2c Magnons and Paramagnons.- 5.2d Two-Current Conduction and Spin Mixing.- 5.2e Curie Point Anomalies.- 5.3 The Phonon-Drag Thermopower of Transition Metals.- 5.4 Magnon Drag.- 5.5 Transition Elements: Summary of Experimental Results.- 5.5a The Magnetic Elements: Cr, Mn, Fe, Co, and Ni.- 5.5b The “Thermocouple” Elements: Fe, Pt, Re, and W.- 5.6 Commercial Thermocouples.- 5.6a Copper vs. Constantan (Type T).- 5.6b Iron vs. Constantan (Type J).- 5.6c Chromel vs. Constantan (Type E).- 5.6d Chromel vs. Alumel (Type K).- 5.6e Tungsten vs. Tungsten—Rhenium (Types G* and C*).- 5.6f Platinum vs. Platinum—Rhodium (Types R, S, and B).- 6. Dilute Magnetic Alloys.- 6.1 Introduction.- 6.2 The Virtual Bound State.- 6.2a Electronic Properties for VBS Systems.- 6.2b Survey of Experimental Results for VBS Systems.- 6.3 Kondo Alloys.- 6.3a Theory of the Kondo Effect.- 6.3b Thermoelectric Power of Kondo Alloys.- 6.4 Spin-Fluctuation Models.- 6.5 Closing Comment.- 7. Effects of Pressure and Magnetic Field on the Thermoelectric Power.- 7.1 Pressure Dependence.- 7.1a Introduction.- 7.1b Practical Thermocouples.- 7.1c Fundamental Studies.- 7.1c1 Diffusion Thermopower.- 7.1c2 Phonon-Drag Thermopower.- 7.2 Magnetic Field Dependence.- 7.2a Introduction.- 7.2b Practical Thermocouples.- 7.2c Fundamental Studies.- 7.2d Landau Quantization Effects.- References.- Author Index.