Structural and luminescence studies on Eu3+: B2O3-Li2O-MO-LiF (M=Ba, Bi2, Cd, Pb, Sr2 and Zn) glasses

The present work reports the structural and luminescence studies on 54B(2)O(3)+25Li(2)O+15MO+5LiF+1Eu(2)O(3) (where M=Ba, Bi-2, Cd, Pb, Sr-2 and Zn) glasses prepared by following melt quenching technique. The influence of the metal ions in the host matrix have been studied by measuring FTIR, absorption, excitation and emission spectra. FTIR studies explore the presence of the functional units in the prepared glasses. Through the optical absorption spectra bonding parameters ((beta) over bar, delta), direct and indirect allowed band gap and Urbach energy (Delta E) values were calculated and reported. Due to some defects associated with the addition of various oxides in to the host matrix, the Urbach energy values changes inversely with the optical band gap. The phonon side band have also been observed on the high energy side of the F-7(0) -> D-5(2) transition in the excitation spectra due to the coupling between the coordination ions and Eu3+ ions. Judd-Ofelt (JO) intensity parameters have been determined from the luminescence spectra and is used to explore the nature of the Eu3+ ions with its surrounding ligands. The JO parameters have been used to calculate the stimulated emission cross-section (sigma(E)(P)), branching ratios (beta(R)) and radiative lifetime (tau(R)) for the D-5(0) -> F-7(J) (J=1, 2, 3 and 4) transitions of the Eu3+ ions in the prepared glasses. The experimental lifetime of the D-5(0) level in the Eu3+ doped lithium fluoroborate glasses have been calculated and reported. The longer lifetime of the D-5(0) metastable state indicates that the prepared glasses are suitable for laser applications. (C) 2013 Elsevier B.V. All rights reserved.