Directional Solidification and Thermoelectric Properties 
of Undoped Mg2Sn Crystal
Single-phase Mg2Sn crystal has been successfully directionally solidified from the melt with a high temperature gradient of 185 K cm−1. The solidified distance for the growth of single-phase Mg2Sn crystal was predicted theoretically and agreed well with the experimental result. The grown Mg2Sn crystals exhibit better thermoelectric performance and high thermoelectric figure of merit along the growth direction. In the temperature range from 300 K to 700 K, the maximum Seebeck coefficient S and electrical conductivity σ reached −261 μV K−1 and 525 Ω−1 m−1, respectively. The minimum thermal conductivity κ was measured to be 4.3 W m−1 K−1, and the lattice thermal conductivity approximated 90% of the bulk thermal conductivity of the crystal. The method developed in this work provides a methodological reference for preparation of Mg2BIV and its doped and solid-solution compounds.