Spectroscopic properties of Eu3+ ions doped Barium telluroborate glasses for red laser applications

Eu3+ ions doped,Barium telluroborate glasses were prepared by melt quenching technique with the chemical composition (30 - x) TeO2 + 30B(2)O(3) + 20BaO + 20BaF + xEu(2)O(3) (where x = 0.05, 0.1, 0.5, 1.0, 2.0 in mol%). The presence of different vibrational bands in the title glasses was explored from FIIR and Raman spectra. From the Nephelauxetic ratios (beta) and bonding parameter (delta) values, the metal-ligand bond is found to be covalent in nature and is found to increase with the increase in Eu3+ ions concentration. The electron-phonon coupling constant (g), phonon energy of the host (h omega) and the multiphonon relaxation (W-MPR) were determined from the excitation spectrum of the prepared glasses. The luminescence intensity ratio (R) between the electric (D-5(0) -> F-7(2)) and magnetic dipole transition (D-5(2) -> F-7(1)) was found to increase with the increase in Eu3+ ions concentration thus confirms that the Eu3+ ions were occupied in a highly asymmetrical environment. Judd-Ofelt intensity parameters (Omega(2), Omega(4) Omega(6)) were determined from the luminescence spectra and the value of Omega(2) was found to increase with the increase in Eu3+ ions concentration thus confirms the increasing covalent nature. The radiative parameters such as spontaneous transition probability (A), branching ratio (beta(R)) and stimulated emission cross-section (sigma) were found to be higher for the D-5(0) -> F-7(2) transition compared to the other transitions. Among the prepared glasses and compared to the reported glasses, transition probability, stimulated emission cross-section and branching ratio pertaining to the D-5(0) -> F-7(2) transition of the BTBa1.0Eu glass was found to be higher thus suggests its suitability for red laser applications. The CIE color chromaticity co-ordinates (0.622, 0.378) found to exhibit dominant red emission with the increase in Eu3+ ions concentration in the prepared glasses. The decay curves exhibit single exponential behavior for all the title glasses and the non-radiative decay rate (W-NR) was found to decrease with the increase in Eu3+ ions concentration. (C) 2017 Elsevier B.V. All rights reserved.