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.