First-Principles Study of Ca3Sc2Si3O12:Ce3+ Phosphors

Charge compensation plays a very important role in modifying the local atomic structure and moreover the spectroscopic property of an isolated luminescent center, and so has been widely adopted in phosphor designs. In this work, we carry out first-principles calculations on various cases of Ce3+ centers in Ca3Sc2Si3O12 by considering the effects of the charge compensations related to N3-, Sc3+, Mn2+, Mg2+, and Na+. Firstly, the local structures around Ce3+ are optimized by using density functional theory calculations with supercell model. The 4f -> 5d transition energies of Ce3+ are then obtained from the CASSCF/CASPT2/RASSI-SO calculations performed on Ce3+-centered embedded clusters. The calculated energies support the previous assignments of the experimental spectra. Especially, a previously unclear peak is identified to be caused by Sc3+ substituting Si4+. The results show that the first-principles calculations can be used as an effective tool for predicting and interpreting spectroscopic properties of the phosphors.