Growth and near-infrared luminescence properties of Yb–Bi co-doped PbWO4 crystal

Bi doped and Yb–Bi co-doped PWO crystals were prepared by Bridgman method. The absorption, photoluminescence and near-infrared (NIR) emission spectra were measured at room temperature. No NIR emission was detected in Bi doped PWO crystal even after γ-ray irradiation. Two isolated emissions peaking at 1360 nm and 1570 nm were observed in Yb–Bi co-doped PWO crystal under the excitation of 940 nm. The low-valence-state Bi+ ions should be the first possible source of the NIR luminescence of Yb–Bi: PWO crystal.

► Yb–Bi: PWO crystal with a size of Φ20×60 mm3 were prepared by the modified Bridgman method.
► Bi: PWO crystal is not luminescent in NIR region.
► With the sensitization of Yb3+ ions, Yb–Bi: PWO crystal presents two weak NIR emission bands.
► The serious radiation damage of Bi: PWO exclude Bi5+ ions as the possible source of NIR emission.
► The low-valence-state Bi+ ions should be the first possible source of the NIR emission.