Microstructure and thermoelectric properties of arc-melted silicon borides

Silicon borides in a boron content range of 80 to 94 mol% were prepared by arc-melting. As-melted specimens consisted of SiB/sub n/ (hexagonal, n=14-49) and free silicon. The free silicon content decreased with increasing boron content in raw materials. The arc-melted specimens were annealed in an argon atmosphere at 1663 K. By annealing for 1.8 ks, SiB/sub 4/ phase formed at the Si-SiB/sub n/ boundary. By annealing for more than 5.4 ks, SiB/sup 6/ phase formed and SiB/sub 4/ phase disappeared. SiB/sub n/ content increased with increasing annealing time. The annealing for 5.4 ks caused a great increase of the Seebeck coefficient.