Effect of photo-thermo-induced nucleation on crystallization properties of SiO2–Al2O3–ZnO–Na2O photo-thermo-refractive glass

Photo-thermo-refractive (PTR) glass is a kind of photo-thermo-sensitive silicate glass. After photo-thermo treatment, it can precipitate sodium fluoride (NaF) crystals in the glass matrix to change the refractive index, which is widely used in volume holographic devices. The purpose of this paper is to study the effect of photo-thermo-induced nucleation on the crystallization kinetics of PTR glass, and several techniques, such as SEM, DSC, absorption spectrum, and XRD, are used to analyze the properties of the induced nucleation process. The results show that photo-thermo-induced nucleation can significantly change the crystallization ability of PTR glass and affect the size, morphology, and volume fraction of precipitated NaF crystals. The reason lies in the change in the composition and number of silver nuclei under different photo-thermo-nucleation treatment systems. According to the obtained results, the photo-thermo-induced nucleation processes of PTR glass will be helpful for improving the properties of volume Bragg gratings (VBGs) and other optical elements based on PTR glass. •The isothermal and non-isothermal crystallization experiment were carried out.•The crystallization activation energy of PTR glass was calculated by Kissinger formula.•The composition of silver nucleus was analyzed by absorption spectrum.•The volume fraction of NaF crystals was quantitatively analyzed by XRD.•The nano NaF crystals embedded in PTR glass matrix was clearly photographed.