Microstructure investigations of Yb- and Bi-doped Mg2Si prepared from metal hydrides for thermoelectric applications

1% or less addition of YbH2 to Mg2Si significantly reduces the thermal conductivity of the material. Yb replaces some Mg in Mg2Si and the remainder is distributed as Yb3Sb5 in the Yb-doped Mg2Si matrix. Correlation between the observed grain size and transport show the difficulty in simultaneously reducing the thermal conductivity with optimal electronic properties.173