Microstructure and Thermoelectric Properties of n- and p-Type Doped Mg₂Sn Compounds Prepared by the Modified Bridgman Method

摘要

Mg₂Sn compounds were prepared by the modified vertical Bridgman method, and were doped with Bi and Ag to obtain n- and p-type materials, respectively. Excess Mg was also added to some of the ingots to compensate for the loss of Mg during the preparation process. The Mg₂Sn samples were characterized by x-ray diffraction (XRD) and scanning electron microscopy (SEM), and their power factors were calculated from the Seebeck coefficient and electrical conductivity, measured from 80 K to 700 K. The sample prepared with 4% excess Mg, which contains a small amount of Mg₂Sn + Mg eutectic phase, had the highest power factor of 12 × 10−3 W m−1 K−2 at 115 K, while the sample doped with 2% Ag, in which a small amount of eutectics also exists, has a power factor of 4 × 10−3 W m−1 K−2 at 420 K.