Composition and structure of copper halide phase in sodium and potassium aluminoborosilicate glasses

The structure and composition of copper halide phase regions in sodium and potassium aluminoborosilicate glasses are investigated by the small-angle X-ray scattering (SAXS) technique. The influence of glass composition and chlorine content on the composition of copper halide phase is examined. It is demonstrated that the copper halide phase contains alkali metal halides. Upon cooling the glass below the temperature of the primary heat treatment, the liquid breaks away from the vitreous matrix. This is attended by the formation of "vacuum pores" (cavities free of condensed material) and also by breaking of liquid drops into smaller droplets with the sizes responsible for the sizes of crystals and their melting (liquidus) and crystallization temperatures. The structure of copper halide phase regions depends on the thermal history of a sample, specifically on the heat treatments at intermediate temperatures.