An evidence for a microscopic phase separation in AsSeAg glasses
revealed by thermal and structural investigations |
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Authors: | Pulok Pattanayak S Asokan |
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Institution: | (1) Department of Instrumentation, Indian Institute of Science, Bangalore, 560012, India |
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Abstract: | 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. |
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Keywords: | PACS" target="_blank">PACS 61 43 Fs Glasses 65 60 +a Thermal properties of amorphous solids and glasses: heat capacity thermal expansion etc |
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