Laser Patterning of ZnO Crystals on the Surface of Borosilicate Glass

The laser-induced crystallization technique has been applied to a borosilicate glass with a high ZnO content in order to pattern ZnO crystals on the glass surface. A glass with the composition of 65.5ZnO–19B2O3–9.5SiO2–6Sm2O3 is developed, in which Sm2O3 is added to transfer laser energy to thermal energy, and it is found that usual heat treatments in an electric furnace results in the formation of ZnO crystals with a hexagonal wurztite structure not only at the surface but also inside the glass. It is confirmed from X-ray diffraction analyses and micro-Raman scattering spectra that ZnO crystals are formed at the glass surface by irradiations of Yb:YVO4 fiber laser (wavelength: 1080 nm, power: 1.3 W, scanning speed: S=7 μm/s). The present study is a first step for spatially selected patterning and design of functional ZnO crystals by laser-induced crystallization in glasses.