Structural, thermal and optical studies of Ni3Se2 compound produced by mechanical alloying

The Ni3Se2 compound was obtained by mechanical alloying starting from a binary mixture of pure crystalline powders with nominal composition Ni75Se25. X-ray diffraction (XRD), transmission electron microscopy (TEM), differential scanning calorimetry (DSC) and Raman scattering (RS) techniques were used to follow the structural, thermal and optical properties of the binary mixture as a function of milling time. XRD results showed the formation of trigonal Ni3Se2 phase from 3 up to 70 h of milling coexisting with non-reacted fcc-Ni phase. DSC and RS results showed high stability of the thermal and optical properties of the Ni3Se2 phase when the milling time increases. The Raman active modes of the Ni3Se2 phase, which are missing in the literature, were determined. No other phases, such as iron selenides, nickel oxides and selenium oxides, were detected.