Development of High Performance p-Type Bisbte Based Alloys By Powder Metallurgy

Abstract

Due to the rapidly increasing global demands for alternative energy sources, thermoelectric materials are receiving great attention compare to other renewable energy sources due to the exhibiting excellent characteristic features such as no moving parts, silent, reliable, environment freely and minimum maintenance. TE devices are the semiconductor systems that can either directly convert thermal energy into electricity for power generation, or perform cooling or heating with electric power. So far, single (unidirectional) crystal growth techniques such as zone melting and czochralski were used to produce TE material in which the maximum ZT of TE materials almost unity ( ZT= 1) was obtained. However, these crystals having cleavages along the basal plane and got easily fractured. Nevertheless, improving mechanical properties was elusive so far due to exhibiting coarse grain size and gets easily fractured during the manufacturing. Recent studied showed that the powder metallurgy methods (PM) have been attaining best TE properties as well as mechanical properties. TE alloys by gas atomization is one of the well adopted processes, can easily make powders in large scale. In this research, we have fabricated thermoelectric alloys by gas atomization then subsequently consolidated by SPS. The phase analysis, and microstructure of powders and bulks were characterized by X-ray diffraction and scanning electron microscopy respectively. The temperature dependence of electrical resistivity and Seebeck coefficient were systematically investigated from room temperature to 500 K. The figure of merit, ZT is calculated from the measured Seebeck coefficient, electrical conductivity, and thermal conductivity values.