Synthesis and Characterization of High-Energy Ball-Milled Nanostructured Fe25Se75

Iron Selenide (Fe25Se75) powders have been synthesized by mechanical alloying from pure elemental Fe and Se powders in a high-energy planetary ball mill. Morphological, compositional, structural and thermal changes during milling have been analyzed by scanning electron microscopy coupled to energy dispersive x-ray analysis, x-ray diffraction (XRD) and differential scanning calorimetry (DSC). With milling time up to 6 h, combined XRD patterns and DSC show α-Fe as well as some amorphous selenium. For the samples milled between 10 h and 20 h, the orthorhombic FeSe2 and β-FeSe hexagonal nanometric phases are formed and the volume fraction of the α-Fe phase decreases. As for 33 h and 52 h of milling, the α-Fe phase completely disappears and a new phase emerges, also in nanometric scale, typical of Fe7Se8 phase.