The influence of temperature gradient on energy resolution of Bi4Ge3O12 (BGO) crystal

In this work, we grew Bi4Ge3O12 (BGO) crystals of two types by Bridgmen–Stockbarger technology in different temperature gradients and compared their optical transmissions and energy resolutions before and after ultraviolet irradiation. It was found that the optical transmissions and energy resolutions of the two types of BGO crystals are similar before UV-irradiation. After UV-irradiation, the optical transmissions at 480 nm of the first type of BGO crystals which were grown in higher temperature gradient cut down about 20% and their energy resolutions obviously deteriorated from about 12–18%. But the optical transmissions and energy resolutions of the second type of BGO crystals which were grown in lower temperature gradient keep unchanged on the whole. After 250 °C/4 h annealing, the optical transmissions and energy resolutions of the second type of BGO crystals can be completely recovered, whereas the optical transmissions and energy resolutions of the first type of BGO crystals cannot be completely recovered until through 600 °C/8 h annealing. The reason for the difference between the first and second type of BGO crystals is discussed.