Thermoelectric property and microstructure of iron-silicide dopedwith Co and Ag


T. Morimura1, M. Hasaka2,T. Watanabe3


1Graduate School of Science and Technology, NagasakiUniversity, 1-14 Bunkyo-machi, Nagasaki 852-8521, Japan

2Department of Materials Science and Engineering,Faculty of Engineering, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki852-8521, Japan

3Department of Chemical andBiological Engineering, Sasebo National College of Technology, 1-1,Okishin-cho, Sasebo 857-1193, Japan


b-FeSi2is enumerated as a prospective material for thermoelectric conversion as wellas photoelectric conversion and light emitting. In this investigation,thermoelectric property and microstructure of b-FeSi2 wereinvestigated by the measurements of Seebeck coefficient, electricalresistivity, X-ray diffraction and transmission electron microscopicobservation. e-FeSi and a-FeSi2were observed in an as-cast sample. b-FeSi2 were produced bytransformation from e-FeSiand a-FeSi2after annealing at 1073K. b-FeSi2 hardly contained Ag butcontained Co as a dopant. Ag precipitated in the boundaries of b-FeSi2grains and within the grains. Power factor was enhanced by Ag addition becauseof the decrease in electrical resistivity. The distribution of Ag was importantfactor for the power factor. The information about site occurpancy of Co atomsin b-FeSi2was obtained by energy dispersive X-ray spectra. The relation betweenmicrostructures and thermoelectric properties were revealed.