Study of As₂Se₃and As₂Se₂Te glass structure by neutron- and X-ray diffraction methods

Abstract

Study of As 2 Se 3 and As 2 Se 2 Te glass structure by neutron-and X-ray diffraction methods From the analysis of the partial atomic correlation functions and structure factors the first and second neighbour distances, coordination numbers and bond-angle distributions were calculated. It is established that substitution of Se by Te does not change the basic glassy network structure. For the As-Se bonding is revealed that the first neighbour distance is at 2.42 Å, the average coordination numbers are CN AsSe =2.60.1 and CN SeAs =1.80.1 atoms and the three-atom-bond angle for <Se-As-Se>, <As-Se-As> configurations is 95, the same value within limit of error, as obtained from RMC calculations.

Investigation of the Atomic Structure of Ge-Sb-Se Chalcogenide Glasses

“…In order to avoid unreasonable short-range orders for all atom pairs, in the RMC simulation procedure constraints were applied to the minimum interatomic distances between atom pairs (cutoff distances). The starting cut-off distances were taken from the previous studies for the similar contents [15,17] and from the literature based on the results of similar or very close glassy compositions [29,30]. Several RMC runs have been performed by modifying slightly the cutoff distances for each atom pairs.…”

“…In addition, theoretical modeling of such experimental 2 Advances in Condensed Matter Physics results using Reverse Monte Carlo (RMC) method allows building three-dimensional structure models and, thus, obtaining a more detailed description of the atomic-scale glassy structure. In connection with this, we have successfully performed experiments combining the ND and XRD techniques and RMC simulation method for the study of ternary As-Se-Te [15] and quaternary Ge-Sb-S(Se)-Te glasses [16][17][18]. Using the experience gained, we have started to investigate new Ge-Sb-Se system.…”

“…By this way, characteristic parameters, such as structure factors, partial atomic pair correlation functions, coordination numbers, and bond-angle distribution functions, are established. Recently, the chemical short order in Ge 20 Sb x Se 80-x (x=5, 15,20) compositions has been studied by the nuclear techniques and extended X-ray absorption fine structure measurements [19] as one of the compositions, namely, Ge 20 Sb 20 Se 40 , is among the compositions we study herein. Our results obtained by the combination of different methods would widen the knowledge about these materials and would contribute to a better understanding of the structural changes by composition.…”

“…Appropriate quantities from Ge, Se, and Sb were sealed into quartz ampoules after evacuation down to a pressure of 10 -3 Pa. The bulk glasses were synthesized by the conventional meltquenching method in a rotary furnace at 950 ∘ C. After Sb 40-x Se 60 (x=40,35,32,27,20,15 at.%) is displayed: experimental data (colour marks) and RMC simulation (solid lines). For better clarity, the curves are shifted vertically.…”

Reversible devitrification in amorphous As2Se3 under pressure

“…Figures 1(a) and 1(b) shows XRD patterns of a-As 2 Se 3 in Q space during compression and decompression, respectively. Under ambient conditions, and persisting to some extent as the pressure is increased, there is a prepeak in the XRD patterns near Q = 1.3Å −1 ; this corresponds to a 2D layered structure [25][26][27][28][29]. As the pressure is increased, the prepeak shifts to higher Q values and loses intensity, finally disappearing ∼13.5 GPa [ Fig.…”