Radiation-induced color centers in γ-irradiated glasses in the Na2O-Nb2O5-P2O5 system

Abstract

The specific features of the induced optical absorption spectra of glasses in the 45Na2O · xNb2O5 · (55 − x)P2O5 system with Nb2O5 contents x = 5, 10, 20, 25, 30, and 35 mol % are investigated as functions of the irradiation dose and the heat treatment time. The spectra are decomposed into Gaussian components with the use of computer processing. It is revealed that the glass composition and the irradiation dose affect the number, type, and parameters of the bands associated with the PO 4 2− hole-type centers, electron-type color centers of the phosphate matrix, [Nb(5+)−] one-electron centers, and [Nb(5+)−-O-Nb(5+)−] two-electron centers. The inference is made that heat treatment at temperatures close to the glass transition point T g leads to the formation of groupings with a structure similar to structural motifs of NaNbO3 crystals. It is demonstrated that these groupings are responsible for the induced optical absorption in the near-IR spectral range.