Effect of lead vaporization in growth process on the luminescence property of PbWO4 crystal

PbWO4 crystals were grown by Bridgman and Czochralski method, respectively. The ratio of Pb to W in the crystals was lower than stoichiometry because of the lead vaporization from the melt in growth process. The atomic ratio of Pb to W became lower gradually from head to tail of the crystal. This resulted in the decrease of transmittance and the decrease of intensity of emission peak. At the same time, the emission peak was shifted to the longer wavelength. Compared with Czochralski method, the vaporization of lead was well controlled in growth process of Bridgman.