Thermoelectric Properties of Fe-Mn-Si Alloys and Compound Fe₃Si doped with Mn and V

Abstract

Thermoelectric properties of Fe₃Si with the DO₃ structure where some Fe were replaced with Mn and V were examined. By adding 5 mol%Mn or V, the Seebeck coefficients, α, reach the maximum values of about+22.5 μV/K, while they decreased to a large negative value by the further replacement of Fe by these transition elements. The minimum values of α were −36 μV/K and −45 μV/K at Fe-30 mol%Mn-25 mol%Si and Fe-20 mol%V-25 mol%Si, respectively. These values are smaller than the minimum value reported for the iron-based alloys. The compositional dependency of α corresponds to the fact that the added transition metal atoms replaced iron atoms at a particular site in the DO₃ lattice. By combining an approximate model approximation suitable for simple metals and the density of state reported, however, the obtained compositional dependency of thermoelectricity could not be explained. The absolute values of α in the Fe-Mn-Si system were small, both in the samples with the α-Fe solid solution and with the γ-Fe solid solution.