XRD, DSC, MS and RS studies of Fe75Se25 iron selenide prepared by mechano-synthesis

The structural evolution of an Fe75Se25 powder mixture under ball milling was investigated as a function of milling time. It was followed using the X-ray diffraction (XRD), differential scanning calorimetry (DSC), Mossbauer spectroscopy (MS) and Raman spectroscopy techniques. From the XRD patterns, it was observed that the beta-FeSe and/ or Fe7Se8 phase is formed for milling times between 3 and 60 h and the balance of non-reacted alpha-Fe powder is reduced to nanometric scale. For longer milling times no other crystalline phases were observed. The Mossbauer measurements showed small amounts of iron oxide between 3 and 10 h of milling, which was not observed for milling times longer than 20h. The DSC and MS results indicate the existence of an amorphous-like FeSe alloy with low crystallization temperature. The Raman measurements showed the characteristic natural vibration modes of the N-FeSe and/or Fe7Se8 phase. (C) 2003 Elsevier B.V. All rights reserved.