Thermoelectric coefficient

Here Et is the intensity of the electric field generated by the particle motion in thermal field, L and L12 - Onsagera kinetic coefficients, olt = L 2 (eTn)-1 T l - thermoelectric coefficients. 

Note also that the diagonal coefficients (Lu, L22 Lit) are always positive, in contrast to the cross-coefficients Ljk- For example, the heat conductivity or electrical conductivity coefficients have always a positive sign, whereas no sign maybe compulsorily ascribed to the thermodiffusion or thermoelectrical coefficients without consideration of a particular system. 

The simplest and most inexpensive temperature monitors are thermocouples, such as copper-constantin (type T). Although the temperature coefficient of the thermoelectric effect is low (39 /nV/K at room temperature for type T), there exist excellent tables for common thermocouples which make them extremely reproducible (see, e.g., the helpful handbook on temperature measurements from Omega Engineering, Stamford, CT). Unfortunately, below about 30 K the thermoelectric coefficient decreases by at least a factor of 10 and thermocouples become not useful (unless one uses exotic and expensive couples like gold/iron). Further, because the voltages measured are so low, artifacts such as ground loops and stray return currents from the typical 1-5 A current being applied to the heater can lead to serious errors. 

In melts, an additional problem of thermo-emf arises, and the emf correction can be calculated from thermoelectric coefficients of phases in contact [35]. 

Electrical conduction and heat transport are closely linked, the connection being described by three thermoelectric coefficients, the Seebeck coefficient (or thermopower), the Peltier coefficient and the Thomson coefficient, all of which have relevance to thermoelectric power generation and refrigeration. In perovskites, the most reported values are for the Seebeck coefficient. The magnitude and sign (+ or -) of the Seebeck coefficient are related to the concentration and type of mobile charge carriers present. For band-like perovskites, the magnitude of the Seebeck coefficient is proportional to the density of states, either in the conduction band, for electron transport, or the valence band for hole transport. 

The thermoelectromotive force (80-1050 K) has been measured by Levin (1981) and electrophysical properties of LaNi2Si2 (temperature dependence of electrical resistance, thermoelectrical coefficient, magnetic susceptibility as well as the preparation of stoichiometric thin films) were reported by Levin et al. (1977). 

Electrical resistivity ps Temperature coefficient Pressure coefficient Electrical resistivity pi Superconducting critical temperature T tit Superconducting critical field Hait Hall coefficient R Thermoelectric coefficient Electronic work function Thermal work function Molar magnetic susceptibility /mol, solid (SI)... 

Hall coefficient R Thermoelectric coefficient Electronic band gap AE Temperature dependence Electronic work function Thermal work function... 

Representative Values of Absolute Seebeck Thermoelectric Coefficients of Some Materials Used in Industrial Electronic Circuits... 

Thermoelectric coefficient Dielectric constant (e - 1), gas 580x10 35 -70 M-V/K At 293K... 

In melts, problem of TLJP (thermo-emf) always arises, and the emf correction is typically calculated from thermoelectric coefficients of phases in contact [83]. However, no detailed research of TUP contribution to this correction is known. The problem is probably close to solvent/solvent junctions. 

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