Precipitation of In2O3 nano-crystallites from glasses in the system Na2O/B2O3/Al2O3/In2O3

Glasses in the system Na2O/B2O3/Al2O3/In2O3 were melted and subsequently tempered in the range from 500 to 700 °C. Depending on the chemical composition, various crystalline phases were observed. From samples without Al2O3, In2O3 could not be crystallized from homogeneous glasses, because either spontaneous In2O3 crystallization occurred during cooling, or other phases such as NaInO2 were formed during tempering. The addition of alumina, however, controlled the crystallization of In2O3. Depending on the crystallization temperature applied, the crystallite sizes were in the range from 13 to 53 nm. The glass matrix can be dissolved by soaking the powdered glass in water. This procedure can be used to prepare nano-crystalline In2O3-powders.