Experimental and first-principles studies on photoluminescence of Ce3+-doped calcium chloroborate Ca2BO3Cl.

The luminescense properties of Ce3+ ions in Ca 2 BO 3 Cl were studied upon excitation in the 3–20 eV range. It is shown that because of the presence of different charge compensating defects, the various types of centers involving Ce3+ are formed in Ca 2 BO 3 Cl. Based on the results obtained, the values of the crystal field splitting and the centroid shift of the Ce3+ 5d configuration for locally uncompensated Ce3+ centers were determined and compared with those of Ce3+ ions in some other inorganic compounds. The DFT calculations were utilized to study the band structure of Ca 2 BO 3 Cl, the 4f→5d transitions of Ce3+ ions and the intrinsic defects of this compound. The calculated band gap of Ca 2 BO 3 Cl (7.22 eV) is consistent with the experimental value of 7.35 eV, and the 4f→5d transition energies for Ce3+ ions on the two sevenfold coordination sites confirm spectral assignments based on the luminescent measurements. The experimental results and first-principles calculations show that the introduction of Na+ hardly influences the luminescence properties of Ce3+-doped Ca 2 BO 3 Cl. The possible processes occurring in Ca 2 BO 3 Cl:Eu2+, Ce3+ persistent phosphors are also discussed based on the combined theoretical and experimental results. • Several types of Сe3+-related centers are observed. • At low Ce3+ concentrations, locally uncompensated Ce3+ centers prevail. • The calculated band gap of Ca 2 BO 3 Cl agrees with the experimental value of 7.35 eV. • VRBE diagram implies the involvement of the CB in the PersL charging process. [ABSTRACT FROM AUTHOR]