Flash-sintering of antimony telluride and its thermoelectric properties

This study set out to examine the flash sintering of thermoelectric materials. A finite element method analysis of electric current activated/assisted sintering with an insulating mold suggested that the use of a sufficiently high Joule-heating rate, such as >10 000 K/s, relative to the thermal diffusion rate of the mold material, can realize uniform sample heating. Based on the analysis results, the sintering of Sb2Te3, a typical thermoelectric material, was conducted with a current feed duration of 1 s, using a sintering apparatus that had been specially devised for flash-sintering. Although a slight reduction in the density and degree of grain alignment was observed, the crystallographic phase was unaffected by the rapid heating, with the thermoelectric performance of the Sb2Te3 sample prepared by the 1-s sintering being comparable with that of a sample that had been conventionally sintered at 773 K for 3 min. This significant reduction in the sintering time can result in the energy consumption for the sintering process being decreased to less than 1% of that required for conventional current sintering. This significant energy-conservation effect of the flash sintering should be appealing from a practical point of view, especially for the fabrication of those thermoelectric materials used for power generation and aimed at energy recovery.