Synthesis,characterization, and thermoelectric properties of nanostructured bulk p-type MnSi1.73, MnSi1.75, and MnSi1.77

P-type higher manganese silicide (HMS) has attracted considerable interest due to its remarkable thermoelectric (TE) properties and potential applications at intermediate and high temperature TE devices. In this study, a series of nanostructured bulk p-type HMS materials with different compositions of MnSi_x (where x=1.73, 1.75 and 1.77) were synthesized via mechanical ball milling and hot-press sintering. The X-ray diffraction analysis of the synthesized materials showed that increasing the Si contents yields to a slight shift to higher diffraction angles. The increase in Si content further resulted in a decrease in electrical conductivity and increase in Seebeck coefficient. The power factor of all three compositions are approximately identical. However, the lowest thermal conductivity was achieved in MnSi_1.75 and resulted in the highest figure-of-merit among all the compositions.