Optical and luminescence characteristics of Eu3+ doped zinc bismuth borate (ZBB) glasses for red emitting device

Zinc bismuth borate (ZBB) glasses with chemical composition of (60-x) B2O3: 30Bi(2)O(3): 10ZnO: xEu(2)O(3) for different Eu2O3 concentrations of x = 1, 3, 5, 7 and 9 mol% were prepared by the conventional melt quenching technique. The density and molar volume of the glasses have been found to increase with Eu2O3 concentration. The IR studies indicated that these glasses were made up of [BiO3], [BO3], [BO4] and [BO] basic structural units. The absorption spectra had revealed two intense bands due to F-7(0) -> E-7(6) (2076 nm) and F-7(1) -> F-7(6) (2198 nm) transitions in the NIR regions. The fractional populations of the (F-7(0)) and (7F1) ground state were 65% and 35%, respectively. Five luminescence bands were observed at 579 nm (D-5(0) -> F-7(0)), 589 nm (D-5(0) -> F-7(1)), 613 nm (D-5(0) -> F-7(2)), 651 nm (D-5(0) -> F-7(3)) and 696 nm ((3)D0 -> F-7(4)), when excited by a 465 nm source, the most intense red emission was found at 613 nm. A shorter decay time of D-5(0) excited state was found with increasing of Eu3+ concentration as more asymmetries were created around Eu3+. For comparison, further investigations were carried out with two other glass structures; bismuth borate glass (BB) and zinc borate glass (ZB), doped with Eu3+ in the same range. The ZBB glasses have exhibited with the highest emission intensity especially at 613 nm; the intensity for the ZBB was around 7 times of the ZB and twice of the BB glasses. (C) 2015 Elsevier Ltd. All rights reserved.