Luminescence spectra of Eu 3+ ions and interstitial oxygen in PbWO 4 crystal

Abstract

The site-selective excitation and emission spectroscopy, and luminescence decay have been investigated under a pulsed, tunable, narrowband dye laser of the 5D 0→ 7F 0 region in the europium ions-doped lead tungstate PbWO 4 (PWO) in single crystal. In as-grown sample, the experimental results show that there is only one 7F 0→ 5D 0 excitation transition indicating the only one Eu 3+ site in PbWO 4 lattices. The sequential annealing treatments were conducted to investigate the effects of oxygen components on the microstructure environments of Eu 3+ in the lattices. The site distribution of Eu 3+ was changed by the annealing in air atmosphere, which could create new sites in PWO lattices. Confirmation of interstitial oxygen and interpretations of charge compensation mechanism for the observed new sites were discussed in the context of site-selective excitation and emission spectra. The main Eu 3+ site is related to the charge compensation by the [(Eu Pb 3+) –V″ Pb–(Eu Pb 3+) ] complex; the other minor new sites after annealing are originated from [(Eu Pb 3+) –O″ i–(Eu Pb 3+) ] defects. Emission spectra excited by 355-laser and RT-Raman spectra were also measured.