Positron annihilation probing of crystallization effects in TAS-235 glass affected by Ga additions

Crystallization effects in Te20As30Se50 glass known also as TAS-235 affected by Ga additions to Ga2Te20As28Se50 and Ga5Te20As25Se50 compositions are probed with positron annihilation spectroscopy in the measuring modes exploring positron lifetimes and Doppler broadening of annihilation line. Occurring of cubic-phase Ga2Se3 droplets with character nanoscale sizes in partially-crystallized Ga2Te20As28Se50 alloy is shown to be associated with agglomeration of intrinsic free-volume voids, this process being enhanced over microcrystalline scale in Ga5Te20As25Se50 alloy. Crystallization changes in the void structure of TAS-235 glass are considered in terms of free-volume evolution under the same principal chemical environment responsible for positron trapping in amorphous and partially crystallized substances.