EXAFS, XRD and RMC studies of an Amorphous Ga$_{50}$Se$_{50}$ Alloy Produced by Mechanical Alloying

Abstract

The local atomic order of an amorphous Ga$_{50}$Se$_{50}$ alloy produced by Mechanical Alloying (MA) was studied by the Extended X-ray Absorption Fine Structure (EXAFS) and X-ray Diffraction (XRD) techniques and by Reverse Monte Carlo (RMC) simulations of its total x-ray structure factor. The coordination numbers and interatomic distances for the first neighbors were determined by means of EXAFS analysis and RMC simulations. The RMC simulations also furnished the partial pair distribution functions $G^{\text{RMC}}_{\text{Ga-Ga}}(r)$, $G^{\text{RMC}}_{\text{Ga-Se}}(r)$ and $G^{\text{RMC}}_{\text{Se-Se}}(r)$. The results obtained indicated that there are important differences among the local structure of the amorphous Ga$_{50}$Se$_{50}$ alloy produced by MA and those of the corresponding crystals, since there are Se-Se pairs in the first coordination shell of the amorphous alloy that are forbidden in the Ga$_{50}$Se$_{50}$ crystals.