Influenceof phase on thermoelectric properties in lanthanum sesquisulfide doped withtitanium
M.Ohta1, S. Hirai1, S. Morita2, T. Nishimura2,Y. Uemura2
Itis well known that gamma-phase of lanthanum sesquisulfide (La2S3)exhibits high figure of merit due to heavy electron system at high temperature.
Thegamma-phase is obtained by transforming the beta-phase, which stabilizes at lowtemperature compared to gamma-phase and behaves like an insulator, at 1573 K.However, the dopant O atoms which are substituted for S atoms stabilize thebeta-phase which is La10S15-xOx with 0 < x≤ 1 at high temperature in excess of 1573 K.
Wehave found that the transformation to gamma-phase is controlled by sinteringthe beta-phase which is La10S14-xOx doped withTi.
We report measurement of thethermoelectric power and the electrical resistivity in lanthanum