Free‐volume nanostructural transformation in crystallized GeS2–Ga2S3–CsCl glasses

Abstract

The free‐volume nanostructural transformation in fully crystallized (80GeS2–20Ga2S3)100–x(CsCl)x, x = 0; 5; 10; 15 chalcogenide glasses was studied by positron annihilation lifetime spectroscopy using mixed positron‐ and positronium‐trapping modes. The CsCl content in GeS2–Ga2S3 glassy matrix changed the defect‐related component in positron lifetime spectra and confirmed the structural void agglomeration in comparison with the base glass. A larger amount of CsCl in (80GeS2–20Ga2S3)85(CsCl)15 glass resulted in void fragmentation due to loosening of the structure. “Pure” positron‐positronium modes calculated by a decomposition formalism show that a realistic process is connected with the expansion of voids formed as a consequence of CsCl addition and complete crystallization into the inner structure of glasses. The CsCl additive formed new positron‐trapping sites in the Ge–Ga–S glassy matrix. The bulk positron lifetime in glasses corresponded to positron trapping occurring in nanocrystalline particles. Interface voids were not particularly large because the characteristic value of 0.27–0.30 ns can be connected with typical free volumes of mono‐ and di‐vacancies.