Thermoelectric property and microstructure of iron-silicide doped with Co and Ag

/spl beta/-FeSi/sub 2/ is enumerated as a prospective material for thermoelectric conversion as well as photoelectric conversion and light emitting. In this paper, thermoelectric property and microstructure of /spl beta/-FeSi/sub 2/ sintered with Ag were investigated by the measurements of Seebeck coefficient, electrical resistivity, X-ray diffraction and transmission electron microscopic observation. /spl alpha/-FeSi and /spl epsiv/-FeSi/sub 2/ were observed in an as-cast sample. /spl beta/-FeSi/sub 2/ was produced by transformation from /spl alpha/-FeSi and /spl epsiv/-FeSi/sub 2/ after annealing at 1073K. /spl beta/-FeSi/sub 2/ hardly contained Ag but contained Co as a dopant. Ag precipitated in the boundaries of /spl beta/-FeSi/sub 2/ grains and between particles. Power factor was enhanced by Ag addition because of the large decrease in electrical resistivity and the slight decrease in Seebeck coefficient. The distribution of Ag was important factor for the power factor. The relation between microstructures and thermoelectric properties was revealed.