THERMOPOWER OF SR1-XLAX TIO3 CERAMICS

被引:106
作者
MOOS, R
GNUDI, A
HARDTL, KH
机构
[1] Universität Karlsruhe, Institut für Technologie der Elektrotechnik, D-76187 Karlsruhe
关键词
D O I
10.1063/1.359731
中图分类号
O59 [应用物理学];
学科分类号
摘要
The thermopower eta 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, eta depends linearly on temperature and on n(-2/3), expected from a degenerate quasi free electron gas. In the case of high temperatures and low n, the absolute value of eta rises with 1.5 . ln10 k/e per decade of temperature and with In10 . 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 m(eff) of 4.2 electron masses can be deduced without the assumption of a transport factor A(e). In the classical range A(e)=3 can be evaluated, requiring only a temperature and lanthanum independent m(eff). 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 approximate to 0.2 (i.e., n approximate to 3.4 . 10(21)/cm(3)). (C) 1995 American Institute of Physics.
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页码:5042 / 5047
页数:6
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