Luminescence properties of Sm3+-doped P2O5–PbO–Nb2O5 glass under high pressure

Abstract

Samarium doped lead phosphate glass modified with niobium having a composition (in mol%) of55P2O5+39.5PbO+5Nb2O5+0.5Sm2O3 hasbeen prepared by the conventional melt quenching technique. The emission spectra and the decay curvesfor the 4G5/2 level of Sm3+ ions have been measured as a function of pressure up to 23.6 GPa at room temperature. Adiscontinuity in the observed shifts and crystal-field splittings as a function of pressurearound 9–10 GPa suggests that a phase transition is taking place in the glass matrix. The, 6H7/2 and 6H9/2 transitions are shifted towards the lower energy side with magnitudes of−7.1,−7.6 and−5.5 cm−1 GPa−1 up to 8.9 GPa(phase 1) and −5.6, −4.9 and −4.4 cm−1 GPa−1 beyond 10.3 GPa (phase 2), respectively. A much stronger increase in the splitting of the and Stark levels with pressure is observed in phase 1 than in phase 2. The lifetime of the4G5/2 level decreases from 2.29 ms (0 GPa) to 0.64 ms (23.6 GPa) with pressure. The decay curves of the4G5/2 level exhibit non-exponential behavior for all the pressures and were fitted by the generalizedYokota–Tanimoto model to probe the nature of the energy transfer process. The best fits withS = 6 indicate that the energy transfer between donor and acceptor is ofdipole–dipole type. The crystal-field splitting experienced by theSm3+ ions in the title glass are found to be larger than those found in borate, K–Ba–Al phosphateand tellurite glasses.