Enhanced thermoelectric figure of merit in Bi containing Sb2Te3 bulk crystalline alloys
Abstract In the present work, the structural and thermoelectrical properties of Sb2 xBixTe3 samples prepared by the usual melting method were studied. The samples were milled, pressed and then annealed under vacuum for 3 h at 250 degC. Investigations of the microstructure and surface morphology were carried out using X ray diffraction analysis, scanning electron microscopy and energy dispersive X ray spectroscopy. The Seebeck coefficient and electrical and thermal conductivities were measured from 300 to 473 K. Thermopower data indicated a p type conduction in the samples. Structural defects were present in Sb2Te3 during Bi addition, acting as scattering centers and leading to a decrease in thermal conductivity, thus increasing the thermopower and power factor. The power factor showed its maximum value of around 24.7 mW/cm K2 for the sample containing the highest Bi content. High figure of merit of 1.14 was recorded for the same sample, indicating that the Bi containing Sb2Te3 and the related alloys are promising materials for more efficient thermoelectric devices.