Phase separation and its relationship with thermoelectric properties in tin-substituted magnesium silicide synthesized from melt

Magnesium silicide-based thermoelectric materials have several attractive attributes, including high performance, low cost, and low toxicity. In contrast to prior work which relied on powder metallurgy methods, this work reports on the solidification process of a potentially high-throughput method to synthesize Sn-substituted magnesium silicide with Bi dopants (Mg₂Si_1−x−ySn_xBi_y) via solidification from melt. This approach yields material with relatively good thermoelectric properties (maximum ZT ~ 1.0), with greatly increased throughput in comparison to powder metallurgy processes. The microstructure and composition were characterized, and the solidification process was elucidated by comparing phase-field simulation to experimentally observed morphologies.