Effect of impurities on the optical properties of PbWO4 crystals

The effect of excess W and La3+, Y3+, and Mo6+ impurities on the luminescence spectra and the thermally stimulated luminescence of PbWO4 crystals is studied. A high tungsten content (up to 1 at %) in the charge mixture results in a high luminescence intensity in the green spectral region. Lanthanum impurity decreases the transmission in the short-wavelength (k > 29 000 cm−1) spectral region. Lanthanum and yttrium impurities decrease the luminescence intensity. At low (102 ppm) concentrations, Mo impurity can somewhat increase the light yield. However, the presence of Mo in PbWO4 shifts the absorption-band edge to longer wavelengths, while an increase in the Mo concentration above 102 ppm decreases the luminescence intensity.