Thermal transport and electrical properties of Se95-xSn5Bix (x=0, 4, 8) chalcogenide alloys

This study reports the structural, thermal-transport and electrical properties of the Se95-xSn5Bix (x = 0, 4, 8) chalcogenide alloys. The x-ray diffraction analysis (XRD) reveals the polycrystalline nature of samples. Transmission electron microscopy (TEM) demonstrates the formation of nano-rods and clusters of nano-particles. Differential scanning calorimetry (DSC) of the samples, x = 4&8 indicates, there may be two co-existed phases in these samples. Thermal conductivity (lambda(e)) shows a decreasing trend with the inclusion of Bi in Se-Sn system. Thermal diffusivity (chi(e)) and volumetric heat capacity (QC(p)) show the optimum value for x = 4. Thermal transport parameters remain almost temperature independent. The dielectric constant/loss decreases with frequency and increases with temperature. Maximum dielectric constant/loss is obtained for the un-doped sample, while for doped samples, the values have decreased with Bi content. The strong dependence of conductivity over temperature is explained in terms of non-overlapping small polaron tunneling (NSPT) for undoped and CBH models for Bi doped samples.