STRUCTURAL INFORMATION IN THE OPTICAL-SPECTRA OF EU3-SYSTEM NA2O-B2O3-SIO2( DOPED GLASSES FROM THE TERNARY)

A series of melt derived sodium berate, sodium silicate and sodium bor osilicate glasses (with low silica content) doped with 1 mol% Eu2O3 we re investigated by means of absorption, luminescence and excitation sp ectroscopy The structural changes of the host glasses induced by the a ddition of the modifier give rise to variations of position, width, cr ystal field splitting and intensity of selected electronic f-f transit ions of Eu3+. Additional information on the structural groups in the n eighbourhood of the rare earth ions is contained in the vibronic sideb ands of the pure electronic transitions. The observed compositional va riations in the spectra of the three glass types are interpreted in te rms of the oxygen polarisability, Eu-O covalency crystal field strengt h and Eu3+ site symmetry The results are compared with the Bray model for the ternary glasses.