Structural, optical and photoacoustic study of Sb2Te3 prepared by mechanical alloying

Nanostructured Sb2Te3 was produced from Sb and Te by mechanical alloying for 3 h. Volume fractions of crystalline and interfacial components of the milled powder were estimated from the X-ray diffraction (XRD) pattern corrected for polarization, re-absorption, and inelastic scattering and converted to electron units using the theoretical value of the mean square scattering factor 〈f2〉 of Sb2Te3. Annealing showed that the particles are stable up to at least 583 K. The influence of the interfacial component on optical and thermal properties of as-milled and annealed Sb2Te3 was studied through Raman and photoacoustic absorption measurements. The contribution of the interfacial component to the thermal diffusivity of milled Sb2Te3 was investigated assuming that the measured thermal diffusivity can be described as a random mixture of crystalline and interfacial components. The large volume fraction of interfacial component in the milled powder seems to be responsible for a significant increase in thermal diffusivity. After annealing at 583 K the value of thermal diffusivity is much smaller, close to the one reported for bulk Sb2Te3.