Thermoelectric properties and microstructure of Co-doped iron-silicides mixed with Ag or Cu

Spin-cast ribbons and sintered discs of the Co-doped iron disilicides mixed with Ag or Cu were prepared and investigated by measuring the Seebeck coefficient, electrical conductivity, power factor, dimensionless figure of merit, and thermal conductivity at 300 K. The microstructure was characterized by powder X-ray diffraction analysis and transmission electron microscopic analysis. The ribbons and bulks possess an n-type of polarity. The Seebeck coefficient, electrical conductivity, power factor, dimensionless figure of merit, and thermal conductivity depend on the Si, Ag, or Cu content. The thermoelectric properties differ from the ribbons to the discs. The Ag or Cu phase disperses at grain boundaries and matrix of the β phase, and contributes to form the β phase, and is effective to improve the thermoelectric properties.