Great Enhancing Overall Performances of YSO:Ce Scintillation Crystals by Ni Codoping

Cerium-doped yttrium oxyorthosilicate (YSO:Ce) scintillation crystals are widely used in mixed radiation field detection, radioactive isotope monitoring, and other fields due to their excellent scintillation properties and low cost. However, the poor coincidence time resolution severely limits their further promotion. In order to resolve this problem, this work first designed and conducted research on Ni²⁺-codoped YSO:Ce crystals, and a series of YSO:Ce,xNi (x = 0, 0.3, 0.6, and 1.5 atom %) crystals were grown using the Czochralski method. It is found that codoping with 0.6 atom % Ni²⁺ can improve the overall scintillation performances of YSO:Ce crystals. In particular, the ratio of light output to scintillation decay time significantly improved by 71%, which is currently the best optimization result reported in the orthosilicate-based scintillation crystals systems. In addition, the afterglow level has been optimized by 2 orders of magnitude, and the energy resolution has been improved from 9.2% to 6.7%, greatly enhancing its potential commercial applications. This is mainly attributed to Ni²⁺ codoping, significantly reducing the concentration of carrier traps in YSO:Ce,xNi crystals, reducing the emission proportion of the slow-emitting center Ce2, and introducing the fast scintillation center Ce⁴⁺ into the crystals. Based on the experimental results, the possible mechanisms of the above phenomenon were discussed in the article.