Effect of impurities and disordering on the photoluminescence of crystals and glasses in the system Li2O - 7GeO2

Abstract

The work is devoted to the study of photoluminescence spectra of weakly polar ferroelectric crystals Li₂Ge₇O₁₅ and Li₂O – 7GeO₂ glasses. For all initial samples was observed the wide intensive luminescence band with maximum in the region of 525–550 nm. The spectral distribution of intensity and the position of the maximum of the band for a Li₂Ge₇O₁₅ crystal depended on the excitation wavelength (λ_ex=405 nm or 365 nm were used). The spectral profile of the luminescence band was broadened in glass containing of 0.67% copper. The intensity of the luminescence band was decreased 6 times for glass doped with Cr³⁺ ions (0.01%) as compared with glass containing Cu²⁺ ions. The intense luminescence band of Cr³⁺ ions with λ_max=659 nm was appeared starting from 600. The assumption about the nature of the broad luminescence band observed in both nominally pure and doped glasses and crystals was made: the source of luminescence can be germanium - oxygen complexes [GeO₄] and [GeO₆] of the tetrahedral and octahedral configuration in the material structure.