Optical and Spectroscopic Investigation of Sm 3+ -Doped Calcium Borotellurite Glasses

Calcium borotellurite glasses, doped with 0.25 mol.% of Sm 2 O 3 , were prepared to investigate the influence of TeO 2 content in their properties. The samples were prepared by a melt-quenching method, with TeO 2 varying from 9 mol.% to 51 mol.% and characterized by volumetric density, optical absorption, refractive index, luminescence and radiative lifetime. The results are discussed as a function of TeO 2 content. The increase of TeO 2 concentration increases the volumetric density and refractive index. The optical absorption spectra present peaks characteristic of Sm 3+ ions. The most intense absorption peak was observed at 402 nm ( 6 H 5/2 → 6 P 3/2 level). The increase of TeO 2 content shifts the band edge to a longer wavelength, resulting in a reduction of optical energy band gap and an increase of Urbach energy. The luminescence spectra show four typical emissions of Sm 3+ at 564 nm, 598 nm, 646 nm and 707 nm, corresponding to 4 G 5/2 → 6 H J ( J = 5/2, 7/2, 9/2, and 11/2) electronic transitions, respectively. The luminescence spectra present a reduction in their intensity with TeO 2 increase, which occurs mainly due to the decrease of the number of ions per cubic centimeter. The luminescence intensity shows a decrease for all the samples with the temperature increase. The experimental lifetime of 4 G 5/2 → 6 H 7/2 transition decreases with the increase of TeO 2 content due to an increase of NBOs in the glass structure.