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Stoichiometric arsenic sulphoselenides as testing probes for positron trapping in chalcogenide glasses

M. HYLA1, J. FILIPECKI1, O. SHPOTYUK1,2,* , M. POPESCU3, V. BALITSKA2,3

Affiliation

  1. Institute of Physics, Jan Dlugosz University, Al. Armii Krajowej 13/15, Czestochowa 42201, Poland
  2. Institute of Materials, Scientific Research Company “Carat”, 202 Stryjska Str., 79031 Lviv, Ukraine
  3. Lviv State University of Vital Activity Safety, Kleparivska str. 35, Lviv, UA-79007, Ukraine

Abstract

Positron annihilation lifetime (PAL) measurements are performed for stoichiometric glassy arsenic sulphide g-As2S3 and selenide g-As2Se3 in order to probe the corresponding model of positron trapping. An ORTEC spectrometer with 22Na source placed between two sandwiched glass samples was used in our experiments, the obtained spectra being treated with LT computer program. Two identical samples of g-A2S3 and g-As2Se3 of about ∼1.5 mm in thickness prepared from high-purity elemental constituents by conventional melt-quenching route and additionally annealed near glass transition to avoid the inner stressed regions were tested. It is shown that two-state positron trapping model is valid for both glasses, the process of positron trapping being saturated in extended free-volume defects like to atomic vacancies and their agglomerates. Despite difference in the character of nanovoid radius distribution estimated theoretically for g-As2S3 and g- As2Se3, they have very close average free volumes resulting in the observed similarity of PAL data. But, in contrast to g- As2Se3, which has at least three sets of nanovoids centered near ~1.5 Å, ~2.3 Å and ~2.9 Å, only two sets of nanovoids centered near ~1.3 Å and at ~2.8 Å are proper to g-As2S3 giving only one variant of fitting..

Keywords

Chalcogenide glasses, Positron annihilation life-time spectroscopy, Positron trapping, Free volume.

Submitted at: July 3, 2007
Accepted at: Oct. 15, 2007

Citation

M. HYLA, J. FILIPECKI, O. SHPOTYUK, M. POPESCU, V. BALITSKA, Stoichiometric arsenic sulphoselenides as testing probes for positron trapping in chalcogenide glasses, Journal of Optoelectronics and Advanced Materials Vol. 9, Iss. 10, pp. 3177-3181 (2007)