Solid-state synthesis and thermoelectric properties of Cr-doped MnSi1.73

Cr-doped HMSs (higher manganese silicides), MnSi_1.73 : Cr_x (x = 0, 0.005, 0.01, 0.02, 0.03), were prepared by using a solid-state reaction and hot pressing. X-ray diffraction analysis and Rietveld refinement confirmed the synthesis of MnSi_1.73. The Cr atoms were confirmed to be soluble in the HMS structure because the lattice constant increased with increasing Cr content (x), and the solid solubility limit of Cr was estimated as x = 0.01. All specimens showed p-type conduction and exhibited degenerate semiconductor characteristics at all temperatures examined (323–823 K). The Seebeck coefficient was decreased and the electrical conductivity was increased by Cr doping. The dimensionless thermoelectric figure of merit ZT was obtained as 0.36 at 823 K for MnSi_1.73 : Cr_0.005 and MnSi_1.73 : Cr_0.01 because the power factor was increased and the thermal conductivity was decreased by Cr doping.