Electronic polarizability, optical basicity, and interaction parameter of La2O3 and related glasses

The electronic polarizability and optical basicity of La2O3 and related glasses have been determined from ultraviolet absorption spectra and calculations based on the Lorentz-Lorenz equation. The optical basicity for La2O3 oxide is found to be 1.07, being much larger compared with typical glass-forming oxides such as B2O3 (0.42) and SiO2 (0.48) but being similar to heavy element oxides such as TeO2 (0.93). The Yamashita and Kurosawa's interaction parameter of La2O3 is 0.03 A(-3), indicating that La2O3 is classified as a normal ionic (basic) oxide, i.e., an ionic bonding character in the La3+-O bond is proposed. Close correlations are confirmed among optical basicity, interaction parameter, and oxygen 1s binding energy in x-ray photoelectron (XPS) spectra for La2O3-P2O5 and other La2O3-containing glasses. It is found from XPS and Raman spectra that La3+ ions in La2O3-P2O5 glasses act as network modifiers, supporting an ionic bonding character in the La3+-O bond. The parameters related to electronic polarizability in La2O3 determined in the present study would be useful for the design of rare-earth containing optical functional glasses. (C) 2002 American Institute of Physics.