Influence of phase on thermoelectric properties in lanthanum sesquisulfide doped with titanium

摘要

The thermoelectric power and the electrical resistivity in lanthanum sesquisulfide (La/sub 2/S/sub 3/) doped with Ti at 300 K were measured over the dopant Ti content ranging from 0.5 wt %. to 15 wt %. The tetragonal (/spl beta/) phase powder which contains impurity oxygen of about 5 atomic % was used as, the starting material. The samples, were prepared by vacuum hot-pressing at the temperature range from 1323 K to 1773 K for 3.6 ks. The phase of the compacts obtained changes with the amount of the dopant Ti content and the sintered temperature from the /spl beta/ phase to the cubic (/spl gamma/) phase. Moreover, the LaS phase is formed at the initial stage in the phase change. The absolute value of the thermoelectric power and the electrical resistivity decrease with the phase change. The compacts which are mainly composed of the /spl gamma/ phase exhibit a large power factor.