Preparation and thermoelectric properties of Mg₂Si fabricated by one-step synthesis method

High-purity magnesium hydride(MgH₂), silicon(Si) and bismuth(Bi) powders were selected as the raw materials to prepare Bi (1mol%)-doped Mg₂Si thermoelectric materials by field-activated and pressure-assisted synthesis(FAPAS) in one step. The synthesis process, phase component and thermoelectric properties were studied, and the results was also compared with that prepared from tube furnace process followed by FAPAS (T+F).The results shows that it's feasible to prepare Mg₂Si pellet with high purity, nano-structure and also lower thermal conductivity in short time in one-step method, which improves the figure of merit greatly. Meanwhile, a little bit extra silicon particle was helpful to improve the thermoelectric performance of materials, so the sample with a ratio of 1.95∶1 has higher ZT value than that of 2∶1. At 725 K, ZT value of the former reaches 0.54.