The influence of preparation conditions and small amounts of SnSe on annihilation characteristics of As-Se glass

Nanovolume positron traps in glassy-like As2Se3

“…Contrary to the previous interpretation of Alekseeva et al [3][4][5], these results were described in terms of saturated positron trapping in extended free-volume defects. However, it was non-ambiguously adopted a fully identical origin for vacancy-type positron traps in chalcogenide crystals and glasses, despite a number of well-known significant differences between these solids.…”

“…Firstly, this ChG was carefully studied by Alekseeva et al in the end of the 70s [3][4][5], the investigated gAs 2 Se 3 samples being prepared in two different thermodynamic modifications. Despite close values of positron lifetimes for both modifications (s 1 % 0.20-0.22 ns and s 2 % 0.36-0.37 ns), the samples prepared with water-ice quenching from 600°C demonstrates the larger I 2 intensity for long PAL component.…”

“…A great number of experimental results on PAL characteristics of chalcogenide glasses (ChG), representing themselves as chemical compounds of IV-V-group elements with chalcogen atoms (S, Se, Te) prepared by conventional melt-quenching method [1], has been accumulated since the 1970s [2][3][4][5][6]. Systemising this data set, one can observe an essential discrepancy for ChG (even of the same chemical compositions) obtained in different research centers.…”

On the correlation between void-species structure of vitreous arsenic selenide studied with X-ray diffraction and positron annihilation techniques

“…The relative intensity of this component I 2 was close to 0.50 in as-prepared samples and did not exceed 0.60 in thermally aged ChG. This result is in good correspondence to other experimental data obtained by Alekseeva et al at the end of the 1970s [22,23], but it evidently contradicts Jensen's experiments in 1994 showing I 2 component rising to as high as 0.75 [24].…”

“…Despite a number of difficulties in meaningful interpretation of the measured PALS data resulting from the absence of reliable correlations with other alternative structural parameters, it was established that g-As 2 Se 3 has typically two positron lifetime components with slight dependence on technological pre-history [22][23][24][25]. In 1994, Jensen et al [24] attributed the longest positron lifetime in g-As 2 Se 3 s 2 % 0.37 ns to saturation trapping of positrons by structurally intrinsic nanovoids, nevertheless, the origin of these nanovoids was wrongly treated in full similarity to crystalline counterpart of this compound.…”