Second harmonic generation of the 4TiO2·46BaO·50B2O3 transparent crystallized glasses

The crystallization of the 4TiO2·46BaO·50B2O3 glasses were investigated. Surface transparent crystallized glasses only containing β-BBO can be obtained when heat-treated at 620 °C for the duration less than 12 h. Then another crystal phase BaTi(BO3)2 will come out following further heat treatment for the period longer than 12 h confirmed by the XRD pattern and Raman spectra. The SEM images of cross section of the sample heat-treated for 8 h indicated that the thickness of crystallized layer is estimated to be about 25 μm. The most intense second harmonic generation is observed in the samples heat-treated for 8 h, which is comparable with the intensity of the reference Y-cut quartz. According to the analysis of crystallization process, we elucidated the evolution of Maker fringe of the crystallized glasses prepared at 620 °C for different durations.