Effects of melt spinning process on microstructure and thermoelectric properties of n-type InSb compounds

Abstract

The single-phase InSb compounds have been prepared by novel melt spinning (MS) technique combined with spark plasma sintering (SPS) method, and the effects of melt spinning process on their microstructure and thermoelectric transport properties have been investigated. The results show that the free surface of ribbon obtained by MS consists of cubic grains with the size of 03—20 μm, and the contact surface of ribbon obtained by MS amorphous-like phases or finer nanostructures have formed, and after SPS the highly dense bulk material with lots of fine layered nanostructure has been obtained of about 40 nm in dimensions. By comparing the bulk InSb material prepared by melting method combined with SPS (Melt+SPS sample) with the bulk InSb material obtained by melting method combined with MS and SPS (Melt+MS+SPS sample)， we see that the MS process leads to a slight decrease in electrical conductivity, and an obvious increase in Seebeck coefficient, as well as a remarkable decrease in thermal conductivity and lattice thermal conductivity for bulk InSb in the testing temperature range of 300—700 K. At 300 K and 700 K, the lattice thermal conductivities of Melt+SPS sample and Melt+MS+SPS sample decrease by the scopes of 106% and 1664%, respectively. As a result, the maximum dimensionless figure of merit ZT of 0.49 is obtained at 700 K for the Melt+MS+SPS sample. Compared with that of Melt+SPS sample, it is increased by 29% at the same temperature.