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.