Associate Professor, Center for Atomic and Molecular Technologies, Graduate School of Engineering,Osaka University, Japan.

Speech Title: Synthesis of thermoelectric β-FeSi2via directly applied current sintering
Abstract: As an electrical conductive powder, thermoelectric β-FeSi2powder, was sintered by spark plasma sintering (SPS) using carbon punches and an insulating quartz glass die. These powders were heated by directly applied current and their sintering behaviors were compared to those of the samples sintered by the conventional SPS (using carbon punches and a carbon die). During the heating in the quartz die, the transformation from mechanically alloyed metallic Fe-Si powder to the semiconductive β-FeSi2phase occurred at a temperature lower than when sintered by the conventional SPS. After the transformation, the shrinkage of compact became larger and the density of a sintered body was higher as compared to those of the sample sintered by the conventional SPS. The sample sintered by this modified SPS process showed the thermal conductivity smaller than the sample prepared in the conventional SPS process because of its finer microstructure. On the other hand, the electrical resistivity and the Seebeck coefficient of this sample were slightly reduced and enhanced, respectively, resulting in the significantly lager figure of merit as compared to the conventionally sintered sample.
Keywords: thermoelectric β-FeSi2powder