Subject thermopower

To conclude this discussion of thermoelectric effects in ice, we should briefly relate the homogeneous thermopower Qh to some of the thermoelectric coeflacients more common in electronic conductors. The whole subject can be treated by the methods of irreversible thermodynamics (Jaccard, 1964 Ziman, i960, pp. 270-5) but we shall follow instead the more transparent micro-scropic treatment (Jaccard, 1963). 

Rare earth intermetallic (RI) compounds have been the subject of many recent experimental investigations because of the nature and variety of their physical properties (Buschow, 1977, 1979 Kirchmayr and Poldy, 1979). In this review article we concentrate on one aspect of such investigations, namely the transport properties of these interesting compounds. We describe in particular experimental data for the resistivity, thermopower and the thermal conductivity. 

Thermoelectric power is the potential gradient generated between two points or faces of a material when they are subject to a temperature differential. Typically, it is large for semiconductors, while for metals it is small and decreases with decreasing temperature, vanishing near absolute zero. A small decrease of thermopower with temperature would thus likely indicate hopping conduction, whilst a very rapid decrease and very low values (see below) for the thermopower would indicate a quasi-metallic conduction, as for instance observed for highly doped trans-P(Ac). 

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