Optical and Spectroscopic Investigation of Sm3+-Doped Calcium Borotellurite Glasses

Calcium borotellurite glasses, doped with 0.25mol.% of Sm2O3, were prepared to investigate the influence of TeO2 content in their properties. The samples were prepared by a melt-quenching method, with TeO2 varying from 9mol.% to 51mol.% and characterized by volumetric density, optical absorption, refractive index, luminescence and radiative lifetime. The results are discussed as a function of TeO2 content. The increase of TeO2 concentration increases the volumetric density and refractive index. The optical absorption spectra present peaks characteristic of Sm3+ ions. The most intense absorption peak was observed at 402nm ((H5/2P3/2)-H-6-P-6 level). The increase of TeO2 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 Sm3+ at 564nm, 598nm, 646nm and 707nm, 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 TeO2 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 TeO2 content due to an increase of NBOs in the glass structure.