Journal of the American Ceramic Society, Vol.98, No.2, 402-407, 2015
Thermal Stability, Optical Transmittance, and Refractive Index Dispersion of La2O3-Nb2O5-Al2O3 Glasses
La2O3-Nb2O5-Al2O3 high-refractive-index glasses were fabricated by containerless processing, and the glass-forming region was determined. The thermal stability, density, optical transmittance, and the refractive index dispersion of these glasses were investigated. All the glasses were colorless and transparent in the visible to near infrared (NIR) region and had high refractive index with low wavelength dispersion. Some of these glasses were found to have significantly high glass-forming ability. These results indicate that the ternary glasses are suitable for optical applications in the visible to NIR region. The effects of the substitution of Al2O3 for Nb2O5 on optical properties were discussed on the basis of the Drude-Voigt equation. It was suggested that the substitution of Al2O3 for Nb2O5 increased the molecular density and suppressed a decrease in the refractive index, even when both the average oscillator strength and inherent absorption wavelength decreased in La2O3-Nb2O5-Al2O3 glasses. These results are helpful for designing new optical glasses controlled to have a higher refractive index and lower wavelength dispersion.