Free-volume correlations in positron-sensitive annihilation modes in chalcogenide vitreous semiconductors: on the path from illusions towards realistic physical description

Abstract

Abstract.A newly modified correlation equation between defect-related positron lifetime  2 (ns) defined within two-state model and corresponding radius R (Å ) of freevolume positron traps in the full non-linear form 1

Positronics of subnanometer atomistic imperfections in solids as a high-informative structure characterization tool

“…The bulk positron lifetimes in all samples are smaller than previously observed τ b ≅ 0.260 ns [ 10 ], corresponding to positron trapping occurring just in the nanocrystalline particles itself. The appeared/disappeared interfacial free-volume voids are not too large, since the characteristic value of τ int = 0.27 to 0.30 ns lifetime can be associated with typical volumes of mono- or diatomic vacancies in chalcogenide-like systems [ 1 , 3 , 14 - 16 ].…”

Photoluminescence of As2S3 doped by Cr and Yb

“…Chalcogenide glasses can be doped by significant amounts of impurities (up to the level of several atomic percents) without essential changing the optical quality [14]. This feature can be connected with the flexibility of the glass network, lesser density of glass as compared to the crystal, presence of nanovoids (which sizes can be estimated from positron annihilation lifetime spectra using different formula [15,16]). It is necessary to note that introduction of rare earth elements can change not only luminescent but also magnetic properties of chalcogenide glasses.…”

Positronics of subnanometer atomistic imperfections in solids as a high-informative structure characterization tool

“…The bulk positron lifetimes in all samples are smaller than previously observed τ b ≅ 0.260 ns [10], corresponding to positron trapping occurring just in the nanocrystalline particles itself. The appeared/disappeared interfacial free-volume voids are not too large, since the characteristic value of τ int = 0.27 to 0.30 ns lifetime can be associated with typical volumes of mono-or diatomic vacancies in chalcogenide-like systems [1,3,[14][15][16]. It is also worthwhile to mention that free-volume interfacial voids in glassy samples affected by more essential fragmentation (50-h annealed samples taken in respect to 10-h annealed ones) are larger as compared with agglomerated free-volume voids (the corresponding value of defectrelated τ int lifetime reaches 0.370 ns).…”