Influence of nitriding on microstructures and thermoelectric properties of Al-doped iron disilicide materials

H. Chen1, X. Zhao1, E. Mueller2, A. Mrotzek2, D.Platzek2

1Department of Materials Science and Engineering, Zhejiang University, 310027, China

2Institute of Materials Research, German Aerospace Center, D-51170 Cologne, Germany

Aluminum doped iron disilicide based thermoelectric materials were prepared by rapid solidification, nitriding treatment and hot uniaxial pressing. Fine grain sizes and dispersed silicon phase have been obtained after annealing at 1073K for 20 hours. Hall measurements showed the carrier concentrations of the nitrided samples were one magnitude lower than those of the samples without nitriding. The Seebeck coefficient a, electrical conductivity s and thermal conductivity k were measured from room temperature to 973K. It was found that the Seebeck coefficients were markedly enhanced by the nitriding treatment, and decreased with increasing aluminum concentration x. The thermal conductivities for the nitrided samples were significantly lower than those without nitriding, but of no much change with different aluminum contents.