Novel gallate-based oxide and oxyfluoride glasses with wide transparency,high refractive indices,and low dispersions

The glass-forming region of a BaO-La₂O₃-Ga₂O₃ ternary system was confirmed and BaF₂-BaO-La₂O₃-Ga₂O₃ new oxyfluoride glasses were prepared by a containerless processing. We also analyzed the physical, thermal, and optical properties of new oxide and oxyfluoride glasses. The direct effects of the substitution of oxygen by fluorine and the effect of BaO and La₂O₃ on the refractive index and Abbe number were discussed on the basis of electronic polarizability and resonance wavelength of oscillator. The refractive indices increased with increasing La₂O₃ concentration because La₂O₃ increased the electronic polarizabilities. Abbe number increased with increasing BaO and fluorine concentration because of the decrease in resonance wavelength of oscillator. By the combination of the BaO, La₂O₃, and fluorine in the gallate glass system, we could obtain novel oxide and oxyfluoride glasses with high refractive index (1.81-1.95) and high Abbe number (31-55). The absorption edge in UV region shifted to the shorter wavelength and IR cut-off wavelength shifted to the longer wavelength with increasing fluorine. Therefore, wide transparent glass was obtained from 262 nm to 11.3 μm.