La3+ distribution and annealing effects in La : PbWO4 crystal

The optical transmission spectra and irradiation induced absorption spectra were measured transversely point by point from the top to the bottom of La :PbWO4 crystal. From the experimental results, it can be clearly seen that La3+ ions distribute inhomogeneously in the crystal, and have pronounced ef fect on suppressing its intrinsic absorption band at 350 nm. Therefore, the correlation between the transmission at 350 nm and the La3+ distribution c oncentration was reasonably discussed. Furthermore, high temperature anneal ing of the crystal in air can also influence its transmission spectra, and how this affects the formation of induced color centers being studied. The annealing temperatures taken are 600, 780, and 960 degrees C, respectively, and when annealed at 960 degrees C, La3+ diffusion in the crystal may occu r, and thus induced color centers may decrease. Finally, it can be conclude d that suitable La doping and annealing at appropriate temperatures can imp rove the radiation hardness of PWO crystal significantly.