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

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 525–550nm. The spectral distribution of intensity and the position of the maximum of the band for a Li2Ge7O15 crystal depended on the excitation wavelength (λex=405 nm or 365nm 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 Cr ions (0.01%) as compared with glass containing Cu ions. The intense luminescence band of Cr ions with λmax=659nm 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.