Structural, thermal, optical and photoacoustic study of nanostructured FeSb2 prepared by mechanical alloying

Mechanical alloying of elemental Fe and Sb powders yielded nanostructured FeSb2, an amorphous phase, along with unreacted Sb. The volume fractions of FeSb2, Sb nanocrystals and interfacial/amorphous components were estimated from the X-ray diffraction pattern of the as-miller powder. The thermal stability of FeSb2 was investigated by heating the powder at 250 °C and 400 °C. The XRD pattern of the sample annealed at 250 °C showed nucleation of Fe3O4 and decomposition of FeSb2. For an annealing temperature of 400 °C, besides crystallization of the amorphous phase, the volume fractions of Sb and Fe3O4 increased and the volume fraction of FeSb2 decreased. The optical band gap energy for samples as-milled and annealed at 400 °C was measured, and a slight decrease in the band gap was observed in the annealed sample. Thermal diffusivity parameter of the as-milled sample and of the annealed sample at 400 °C was also measured, as well as other transport properties. We also studied the contribution of the thermal diffusivity of the interfacial/amorphous component to the thermal diffusivity of the as-milled sample.