Effect of substituting Al2O3 and ZrO2 on thermal and optical properties of high refractive index La2O3–TiO2 glass system prepared by containerless processing

La4Ti9O24 glass and La2O3–TiO2–Al2O3 and La2O3–TiO2–ZrO2 glass systems were prepared by containerless processing. The thermal stability and refractive indices of these glasses were investigated. It was found that these glasses had high refractive indices over 2.29 and high glass transition temperatures. The effects of substituting Al2O3 or ZrO2 for La2O3 or TiO2 in La4Ti9O24 glass on the refractive index is discussed by analyzing the optical parameters of the glasses. The high refractive index of these glasses was due to their large oxygen packing densities and significant electronic polarizabilities of oxygen ions. The substitution of Al2O3 and ZrO2 was effective for the refractive indices and wavelength dispersions.

► High refractive index TiO2-based glasses were prepared by containerless processing.
► La2O3–TiO2–Al2O3 and La2O3–TiO2–ZrO2 glass systems were prepared.
► Refractive indices of these glasses were over 2.3.
► Effect of substitution of Al2O3 on Abbe number was more pronounced than that of ZrO2.