Spectroscopic studies of Eu3+ ions in LBTAF glasses

Optical absorption, excitation and radiative properties of Eu3+ ions in lead borate titanate aluminium fluoride (LBTAF) glasses are reported. The observed energy levels are fitted to the free-ion Hamiltonian model (HFI) by diagonalising the energy matrices of 4f6 electronic configuration. The effect of thermalization on the oscillator strengths of the absorption bands originating from the ground (7F0) and the first excited (7F1) states of Eu3+ ion is discussed. The phenomenological Judd–Ofelt (J–O) parameters obtained by applying the thermal correction to 7F0 → 5D2 and 7F6 absorption oscillator strengths were used to calculate the spontaneous emission probabilities (AR), radiative branching ratios (βR) and lifetimes (τR) for the 5D0 → 7FJ (J = 0–6) emission levels. Room temperature luminescence spectra are recorded for different Eu3+ ion concentrations upon excitation at 393 nm, corresponding to 7F0 → 5L6 transition. The decay profiles of 5D0 → 7F2 transition in the present glasses are single exponential for all the concentrations. The experimental lifetimes (τm) are found to decrease with increase of Eu3+ ion concentration. The results of radiative properties confirm that LBTAF glasses doped with Eu3+ ions emit an intense red luminescence at 615 nm corresponding to 5D0 → 7F2 emission level.