Thermoelectric power of sulphur at high pressure up to 40 GPa

From the thermoelectric power S measurements on sulphur at high pressure P, a hole-type electrical conductivity has been established above 25 GPa. A correlation of the pressure dependence of S with the previously published optical reflectance data has been found. The positive value of S and its decrease with pressure have shown the similarity of the electron structure of sulphur and its neighbours from Group VI - Te and Se. However, a negative magnetoresistance (MR) established at P approximate to 30 GPa points to low mobility of holes and implies an indirect semiconductor gap for sulphur in contrast to the direct gap for Te and Se in the vicinity of the semiconductor-metal phase transition. (C) 2003 WILEY-NCH Verlag GmbH & Co. KGaA, Weinheim.