Effects of WO3 substitution on crystallization behavior and laser patterning in Gd2O3–MoO3–B2O3 glasses

The glasses with the compositions of 22.5Gd2O3–xWO3–(47.5 − x)MoO3–30B2O3 (x = 0–40) were prepared by a conventional melt quenching method, and the crystallization behavior was examined from X-ray diffraction analyses and Raman scattering spectrum measurements. It was found that the substitution of WO3 for MoO3 has a strong effect on the crystalline phase forming during heat treatment. In the case of the glass with x = 10, the formation of both ferroelastic β′-Gd2(WxMo1 − xO4)3 and paraelastic α-Gd2(WxMo1 − xO4)3 crystalline phases was confirmed, and it was suggested that the substitution of WO3 enhances the transformation of β′-Gd2(WxMo1 − xO4)3 crystals to α-Gd2(WxMo1 − xO4)3 at high temperatures. It was confirmed from polarized optical microscope observations and micro-Raman scattering spectra that β′-Gd2(WxMo1 − xO4)3 crystal lines having periodic refractive index changes were patterned by irradiations of continuous wave Yb:YVO4 fiber laser irradiations (wavelength:1080 nm, power: 1.95–2.0 W, scanning speed: 6–9 μm/s).