Thermoelectric properties of B4C-SiBn (n=4, 6, 14) In-situ composites

Abstract

B4C-SiBn (n=4, 6, 14) in-situ composites were prepared by arc-melting and by a heat-treatment in an argon atmosphere. As-prepared specimens consisted of B4C, SiB14 and free-silicon. The SiB4 phase formed by the heat-treatment for 5.4 ks at 1663 K, and SiB6 phase was observed by the heat-treatment for 19.8 ks. The solid solution of Si into B4C and SiB14 was observed after the heat-treatment. The heat-treatment caused almost no change in thermal conductivity, but the decrease in electrical conductivity. The Seebeck coefficient (α) increased significantly by the heat-treatment. The stacking faults associated with metastable SiB4 phase formation could contribute to the increase in α. The greatest dimensionless figure-of-merit (ZT) value obtained in this study was 0.29 at T=1100 K.