An evidence for a microscopic phase separation in AsSeAg glasses revealed by thermal and structural investigations
Department of Instrumentation, Indian Institute of Science, Bangalore, 560012, India
Corresponding author: a email@example.com
Revised: 20 March 2008
Published online: 19 April 2008
Alternating Differential Scanning Calorimetric (ADSC) studies show that Se rich As20Se80-xAgx (0 ≤ x ≤ 15) glasses exhibit two endothermic glass transitions and two exothermic crystallization peaks; the observed thermal behavior has been understood on the basis that As20Se80-xAgx glasses are microscopically phase separated, containing Ag2Se phases embedded in an As-Se backbone. With increasing silver concentration, the Ag2Se phase percolates in the As-Se matrix, with a well-defined percolation threshold at x = 8. A signature of this percolation transition is shown up in the thermal behavior, as sudden jumps in the composition dependence of non-reversing enthalpy, ΔHnr obtained at the second glass transition reaction. Scanning Electron Microscopic (SEM) studies also confirm the microscopic phase separation in these glasses. The super-ionic conduction observed earlier in these glasses at higher silver proportions, is likely to be associated with the silver phase percolation.
PACS: 61.43.Fs – Glasses / 65.60.+a – Thermal properties of amorphous solids and glasses: heat capacity, thermal expansion, etc.
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2008