The thermopower η of Sr1−xLaxTiO3 ceramics was investigated up to x=0.5 and in the temperature range between 150 K and 1200 K. In addition, the carrier concentration n was determined by Hall measurements and by a chemical Ti3+‐analysis. For low temperatures and high n, η depends linearly on temperature and on n−2/3, as expected from a degenerate quasi free electron gas. In the case of high temperatures and low n, the absolute value of η rises with 1.5⋅ln10⋅k/e per decade of temperature and with ln10⋅k/e per decade of carrier concentration, as expected from a classical broad‐band semiconductor obeying the Boltzmann statistics. In the range of degeneration an effective mass meff of 4.2 electron masses can be deduced without the assumption of a transport factor Ae. In the classical range Ae=3 can be evaluated, requiring only a temperature and lanthanum independent meff. Thus, the thermopower of Sr1−xLaxTiO3 ceramics can be described by a constant effective mass and a constant transport factor within a wide range of temperature and lanthanum content. Furthermore, the transition from degeneration to classical behavior can be described as a function of temperature and electron density, e.g., at room temperature it takes place at about x≊0.2 (i.e., n≊3.4⋅1021/cm3).
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Research Article| October 15 1995
Thermopower of Sr1−xLaxTiO3 ceramics
Ralf Moos, Alain Gnudi, Karl Heinz Härdtl; Thermopower of Sr1−xLaxTiO3 ceramics. J. Appl. Phys. 15 October 1995; 78 (8): 5042–5047. https://doi.org/10.1063/1.359731
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