Signature of a silver phase percolation threshold in microscopically phase separated ternary Ge0.15Se0.85-xAgx (0 <= x <= 0.20) glasses

TL;DR

This study identifies a percolation threshold of Ag2Se phases in Ge-Se-Ag glasses at x=0.10, which significantly influences their thermal, mechanical, and conductive properties, revealing a phase transition in the material.

Contribution

It demonstrates the existence of a silver phase percolation threshold in Ge-Se-Ag glasses and links it to changes in thermal and physical properties, providing new insights into their phase behavior.

Findings

Percolation threshold at x=0.10 for Ag2Se phases

Appearance of two exothermic crystallization peaks at threshold

Enhanced super-ionic conduction linked to percolation

Abstract

Temperature modulated Alternating Differential Scanning Calorimetric (ADSC) studies show that Se rich Ge0.15Se0.85-xAgx (0 <= x <= 0.20) glasses are microscopically phase separated, containing Ag2Se phases embedded in a Ge0.15Se0.85 backbone. With increasing silver concentration, Ag2Se phase percolates in the Ge-Se matrix, with a well-defined percolation threshold at x = 0.10. A signature of this percolation transition is shown up in the thermal behavior, as the appearance of two exothermic crystallization peaks. Density, molar volume and micro-hardness measurements, undertaken in the present study, also strongly support this view of percolation transition. The super-ionic conduction observed earlier in these glasses at higher silver proportions, is likely to be connected with the silver phase percolation.