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

Abstract

Eu3+ ions doped Barium telluroborate glasses were prepared by melt quenching technique with the chemical composition (30−x)TeO2+30B2O3+20BaO+20BaF+xEu2O3 (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 FTIR and Raman spectra. From the Nephelauxetic ratios (β) and bonding parameter (δ) 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 (hω) and the multiphonon relaxation (WMPR) were determined from the excitation spectrum of the prepared glasses. The luminescence intensity ratio (R) between the electric (5D0→7F2) and magnetic dipole transition (5D0→7F1) 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 (Ω2, Ω4, Ω6) were determined from the luminescence spectra and the value of Ω2 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 (βR) and stimulated emission cross-section (σ) were found to be higher for the 5D0→7F2 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 5D0→7F2 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 (WNR) was found to decrease with the increase in Eu3+ ions concentration.