Effect of B₂O₃ on crystallization behavior of ZnO–Al₂O₃–SiO₂ glasses

Abstract

The effects of B₂O₃ on the crystallization behavior of ZnO–Al₂O₃–SiO₂ glasses were investigated by DTA and XRD measurements after nucleation heat-treatment (NHT) at various temperatures for 24 h. The addition of B₂O₃ also decreased T_c of glasses. According to XRD measurements, gahnite precipitated as main phase in every composition. Precipitation of quartz or willemite was observed for the glass in which little nucleation occurred because of low NHT temperature. Addition of B₂O₃ promoted the precipitation of willemite instead of quartz. However, the precipitation of these phases was not observed when the nucleation was enough. Crystal sizes became smaller with the increase of the number density of nuclei. On the other hand, they became larger by the addition of B₂O₃. It was found that B₂O₃ addition decreases the nucleation rate and increases the crystal growth rate.