Structural, magnetic and thermal characterization of Fe 50 Se 50 powders obtained by mechanical alloying

Abstract

In this paper, Fe50Se50 alloy powders were synthesized from pure elemental powder by mechanical allowing. The structure, microstructure, morphology, chemical composition and thermal behavior at a function of milling times (0-39 h) were investigated by X-ray diffraction (XRD), scanning electron microscopy attached with energy-dispersive spectroscopy and differential scanning calorimetry (DSC). In addition, the interaction hyperfine and magnetic proprieties was examined by transmission Mössbauer spectroscopy (TMS) and thermomagnetic measurements (VSM) respectively. For milling times up to 6 h, the results of refinement of the X-ray diffraction pattern by MAUD software reveal the formation of the β-FeSe hexagonal, amorphous selenium and nanocrystalline α-Fe. The DSC curves show several exothermic and endothermic peaks associated with various phases' transitions such as the exothermic peak at 103 °C related to crystallization amorphous selenium. However, after prolonging the milling time to 39 h, the XRD shows the formation of α-FeSe phase tetragonal which has plenty of technological interests especially the superconductivity. The Mössbauer spectroscopy confirmed the formation the two-phase paramagnetic hexagonal β-FeSe and α-FeSe tetragonal, according to the XRD and DSC. Measurement of magnetization (VSM) displays that saturation magnetization (MS) decreases as the milling time increases