Structural features of copper halide phase in CuBr-containing glasses

Abstract

The structural changes in copper halide phase regions upon secondary heat treatments of copper halide aluminosilicate glasses at temperatures in the range 20–520°C have been studied by the small-angle X-ray scattering (SAXS) technique. It is revealed that regions of copper halide phase are characterized by the degree of internal dispersion due to the separation of drops of this phase upon cooling and its crystallization. Upon heat treatment at temperatures above the melting point of copper halide phase, the drops within the phase regions coalesce into larger drops, which, in particular, brings about the change in the melting and crystallization temperatures of nanoparticles. It is demonstrated that, upon low-temperature heat treatments (T< T g), copper enters into the regions of copper halide phase, which leads to the change in its composition (enrichment with CuBr) and also to the precipitation of particles of new phase (presumably, amorphous copper) in the free volume (vacuum pore) of copper halide phase regions. The crystallization processes caused by the change in composition and the catalyzing effect of copper particles are observed at temperatures above the liquidus point of copper halide phase precipitated upon the primary heat treatment.