Slow Emission Suppression in YSO:Ce Scintillation Crystals by Cr Codoping

This work systematically investigated the effect of Cr4+ codoping on the spectral composition and scintillation performance of YSO:Ce scintillation crystals. A series of YSO:Ce,xCr (x = 0, 0.1, 0.3, 0.6, 1.0, and 2.0 atom %) crystals were grown with the Czochralski method in a nitrogen atmosphere. The influence of Cr4+ codoping on crystal luminescence was analyzed through transmittance spectra, photoluminescence, and X-ray excited luminescence spectra. Scintillation performance and carrier trap states of the crystals were studied by gamma spectroscopy, scintillation decay dynamics, and thermoluminescence curves. It was found that low concentration Cr4+ codoping can significantly reduce the proportion of long wavelength emission of the Ce2 site without decreasing the crystal YSO:Ce light output. In the case of high concentration Cr4+ codoping, light output decreased rapidly due to Cr4+ forming the intense carrier competition and reabsorption of Ce3+ emission. However, the decay time could be optimized by about 10% without significantly deteriorating the light output using high concentration Cr4+ codoped YSO:Ce crystals as an external filter. This could be more valuable for application. In addition, the possible mechanisms of the above phenomena were discussed based on the experimental results.