High thermoelectric performance and low thermal conductivity of densified LaOBiSSe

We examined the thermoelectric properties of a densified (hot-pressed) sample of the layered BiCh(2)-based (Ch: S, Se) compound LaOBiSSe. The values obtained for the power factor (S-2/rho) when measured perpendicular to the pressing direction (P-perpendicular to) were higher than those when measured parallel to the pressing direction (P-parallel to). The thermal conductivity (kappa) of the samples was also sensitive to the crystal orientation. The values of kappa measured along P-parallel to were lower than those measured along P-perpendicular to. The highest dimensionless figure-of-merit (ZT similar to 0.36) was obtained at around 650K in both directions, i.e., P-perpendicular to and P-parallel to. (C) 2015 The Japan Society of Applied Physics