Free-volume defects investigation of GeS2-Ga2S3-CsI chalcogenide glasses by positron annihilation spectroscopy

The transformation behavior of free-volume defect in (80GeS(2)-20Ga(2)S(3))(100-x) (CsI)(x) = 0, 5, 10, 15 mol%) chalcogenide glasses was studied by employing positron annihilation spectroscopic technique, which could reveal valuable information for in-depth understanding of nano -structural defects in glassy matrix. The results indicate that the structural changes caused by CsI additives can be adequately described by positron trapping modes determined with two-state model. The initial addition of CsI (x = 5 mol%) led to a void contraction, whereas, the void agglomeration occurred with the increase of CsI and the free volume defects of the glasses were obviously reduced. The atomic density p is inversely proportional to the number of these defects. Meanwhile, the UV cut-off edge shifts toward short-wavelength with increasing of CsI. This study provides the valuable information of defects evolution in GeS2-Ga2S3-CsI glasses. (C) 2017 Elsevier B.V. All rights reserved.