Vibrational, optical and structural studies of an amorphous Se_0.90S_0.10alloy produced by mechanical alloying

Abstract

The local atomic order of an amorphous Se(0.90)S(0.10) alloy produced by mechanical alloying was studied by x-ray diffraction and extended x-ray absorption fine structure (EXAFS) data obtained at three temperatures, T = 300, 200 and 30 K. From the cumulant analysis of the EXAFS data, structural properties such as average interatomic distances, average coordination numbers, Debye-Waller factors and anharmonicity, given by the third cumulant, were obtained. The results found indicate that there is alloying at an atomic level, and Se-S pairs are more disordered and distorted than Se-Se ones due to the milling process.

Reverse Monte Carlo simulations of an amorphous Se0.90S0.10 alloy produced by mechanical alloying combining XRD and EXAFS data

“…[14] we knew the density of the alloy, which is ρ = 0.030 atm/Å 3 . Since now we were using two experimental data, the minimum distances between atoms used in our previous study [14] could be inappropriate. Then, we made several simulations changing the minimum distances between atoms, in order to find the best values for these parameters.…”

“…Fig. 3 shows the g ij (r) functions obtained from the RMC simulations considering both XRD and EXAFS data (thick black lines) and considering only XRD data [14] (thin red lines), for comparison, and all structural data obtained are listed in Table 1. Some interesting features can be noted.…”

“…Table 1 Structural parameters obtained for a-Se 0.90 S 0.10 from RMC simulations using XRD and EXAFS data and also using only XRD data (Ref. [14]). …”

“…Considering our alloy, we determined the structural parameters and, by comparing them with those obtained in Ref. [14], we could extract some interesting conclusions. We also obtained the Θ ijk (cosθ) functions, which furnish information about the three-dimensional structures present in the alloy.…”

“…In a recent article [14] we investigated an amorphous Se 0.90 S 0.10 alloy (a-Se 0.90 S 0.10 ) produced by MA. We obtained vibrational properties, by Raman spectroscopy, optical properties, by optical absorption spectroscopy, and structural properties considering extended X-ray absorption fine structure spectroscopy (EXAFS) and synchrotron XRD.…”