Modern Physics of the Thermoelectric Phenomena: Achievements and Problems

Abstract

This chapter discusses internal discrepancies of contemporary conceptions of physics of thermoelectric phenomena (Seebeck, Peltier, and Thomson effects). These conceptions contradict also with experimental data obtained in a wide range of temperature for various materials (pure metals, alloys, Si, Ge, intermetallic and oxide compounds, borides, and silicides). One of these contradictions arises from the energy conservation law and definition of the Seebeck coefficient—the last cannot exceed 86.25 μV/K in any material. This limitation is met in metals and alloys, while in nonmetallic materials it exceeded hundreds and thousands of times. Experimental temperature dependence of the Seebeck coefficient demonstrates the polarity reversal and sharp extrema (increases up to 100–1000 times) for various materials, which are not followed from theory. Constancy of the Seebeck and Peltier coefficients (underlying the definitions of thermoEMF and Peltier heat) contradicts with Thomson formulae requiring temperature dependence of these coefficients (otherwise the Thomson effect is absent in any materials). The role of structural (spatial) inhomogeneity of the thermoelectric material and the wave nature of thermal radiation are discussed for potential physical mechanism of thermoEMF generation. Extension of expressions for charge and thermal energy flow to take into account nonlinear properties leads to huge mathematical complications.