Spectroscopic properties and excited state dynamics of Sm3+ ions in zinc telluro-fluoroborate glasses

Abstract

A new series of trivalent samarium doped B2O3–TeO2–ZnO–ZnF2–CaF2–BaF2 glasses were prepared and their spectroscopic behavior have been studied to understand the effect of Sm3+ ions concentration and to explore the local field effect on the symmetry around Sm3+ ions for the development of laser devices. Local structure and structural behavior are investigated through XRD, FTIR and Raman spectral measurements. The stretching vibrations of B‒O bond in BO3/BO4 units, Te–O stretching vibrations in TeO3/TeO4 units, and bending vibrations of B‒O‒B and Te‒O‒Te bonds were identified from FTIR and Raman spectral studies. Spectroscopic properties are investigated by recording optical absorption, excitation, luminescence and decay profiles. Judd-Ofelt (JO) theory has been implemented to get information about the local structure around Sm3+ ions in the chosen matrix using the experimental oscillator strength values obtained from the intensities of the absorption band transitions. Luminescence spectra of the Sm3+ ions doped present glasses were recorded by monitoring an excitation at 405 nm which exhibits 4G5/2→6HJ (J= 5/2, 7/2, 9/2 and 11/2) intra-4f transitions through an efficient energy transfer process. The luminescence quenching of Sm3+ ions emission were observed beyond 0.5 wt% of Sm3+ ion concentration which is mainly caused by the cross-relaxation process through various cross-relaxation channels and thus concentration-quenching mechanism can be explained by the electric dipole-dipole interaction of the Sm3+ ions. The non-exponential decay curves are well fitted to the Inokuti-Hirayama model for S= 6, which indicates that the nature of interaction takes place between Sm3+ ions for energy transfer through cross-relaxation is of dipole-dipole type.