Luminescence enhancement of Er³⁺ ions and energy transfer in PbWO₄ single crystals

A series of Er³⁺-doped PbWO₄ crystals have been grown by the Czochralski method with good optical quality. Optical absorbance, x-ray excited luminescence, photoluminescence and excitation spectra have been investigated in these Er³⁺-doped PbWO₄ crystals. Efficient luminescence from Er³⁺ ions doped in PbWO₄ is reported. With increasing luminescence of rare earth Er³⁺ ions in PbWO₄ : Er³⁺, the intrinsic luminescence of the PbWO₄ host is seen to decrease intensively. It was demonstrated that excitation into the PbWO₄ host is followed by an efficient energy transfer towards Er³⁺ ions. The excitation bands of Er³⁺ ions overlap with the luminescence spectra of the PbWO₄ host, which supports the hypothesis of resonant energy transfer from host to Er³⁺ ions. Annealing at higher temperature results in further enhancement of the luminescence of Er³⁺ ions in the PbWO₄ host.