Results of detailed investigations of ${\mathrm{Mg}}_2{B}^{\mathrm{IV}}$ $(B^{\mathrm{IV}}=\mathrm{Si},\mathrm{Ge},\mathrm{Sn})$ compounds and their quasibinary alloys are presented. Our analysis revealed that ${\mathrm{Mg}}_2\mathrm{Si}\text{−}{\mathrm{Mg}}_2\mathrm{Sn}$ system has the most promising for thermoelectric applications combination of transport properties and band structure features. The $n$-type ${\mathrm{Mg}}_2{\mathrm{Si}}_{1-x}{\mathrm{Sn}}_x$ solid solutions were studied in broad range of compositions and electron concentration (up to $5\times {10}^{20}{\mathrm{cm}}^{-3}$). Temperature dependencies of figure of merit were determined in temperature range $300\text{–}870\mathrm{K}$ using results of simultaneous measurements of Seebeck coefficient, electrical, and thermal conductivities. The alloy of optimized composition has reproducible figure of merit $Z{T}_{\max }=1.1$. The results of the present study are compared with the data for best modern thermoelectrics.

• Received 19 October 2005

DOI:https://doi.org/10.1103/PhysRevB.74.045207