Structural Properties of Mg2(Si,Ge,Sn)-Based Thermoelectric Materials Prepared by Induction Melting Method

Abstract

We report on preparation of Mg₂(Si,Ge,Sn)-based thermoelectric materials by a direct induction melting method in Al₂O₃ crucible. A 40 g ingot of Mg₂Si_0.8Sn_0.1Ge_0.1 was prepared after addition to the batch 10 wt% of Mg excess. Evolution of crystal structure of the induction melted sample upon annealing and spark plasma sintering (SPS) was tracked by room-temperature X-ray diffraction (XRD) and scanning electron microscopy (SEM) methods. An evidence for the formation of Mg₂(Si,Ge,Sn) solid solution was obtained from the crystal lattice parameter of this phase which was found to be larger than that of undoped Mg₂Si. XRD and SEM indicated that alongside with the main phase of the Mg₂(Si,Ge,Sn) solid solution, an impurity phase of Mg₂Sn exists in the sample. Amount of the Mg₂Sn impurity phase is significantly reduced in spark plasma sintered sample.