Electroconduction and thermoelectricity of terbium oxide films

The dependence of electric conductivity and thermoelectric power of terbium oxide films TbO/sub 1.75-x/ upon the temperature (250 to 600 0C) and oxide composition (x = 0 to 0.25) is investigated. The results obtained are interpreted in terms of the small polaron theory. The thermoelectric power of TbO/sub 1.75/ does not depend on temperature and is equal to -35 μV/K and the dependence of thermoelectric power of TbO/sub 1.75-x/ on the parameter x is in accordance with Heike's formula for the hopping. Also, some parameters of charge transfer mechanism motion are determined. The activation energy of drift mobility of small polarons in TbO/sub 1.75/ is equal to 0.40 eV and the small polaron radius is equal to 0.21 nm. The concentration of small polarons in TbO/sub 1.75-x/ does not depend on temperature and is equal to the concentration of trivalent terbium ions. (author)