Microstructural evolution of La-doped SiB_6 high-temperature thermoelectric material during a Spark Plasma Sintering

摘要

SiB_6 has proved to a potentially useful material because of its excellent thermoelectrical properties above 700℃, low specific gravity, high degree of hardness, and moderate melting point. SiB_6, which has poor sinterability with a conventional sintering technique due to the covalent characteristic, has been successfully densified fully using a spark plasma sintering(SPS) method. The SPS-processed specimens consisted of SiB_6, SiB_4 and SixBy phases. Pure SiB_6 powder were densified fully at the sintering temperature of 1600℃. In particular, it was found that the rare earth element was very effective in evolving the microstructure of SiB_6 phase, resulting in reducing the sintering temperature and controlling grain growth. These effects were discussed in details in terms of microstructure evolution during the SPS process.