A Photoluminescence Study of Eu, Tb, Ce Emission in Doped Crystals of Strontium-Barium Fluoride Borate Solid Solution BaSr(BO)F (BSBF).

The present study is aimed at unveiling the luminescence potential of BaSr(BO)F (BSBF) crystals doped with Eu, Tb, and Ce. Owing to the incongruent melting character of the phase, the NaF compound was used as a solvent for BSBF crystal growth. The structure of BSBF: Eu with EuO concentration of about 0.7(3) wt% was solved in the non-centrosymmetric point group 6. The presence of EuO in BSBF: Eu leads to a shift of the absorption edge from 225 nm to 320 nm. The photoluminescence properties of the BSBF: Ce, BSBF: Tb, BSBF: Eu, and BSBF: Eu, Tb, Ce crystals have been studied. The unusual feature of europium emission in BSBF is the intensively manifested D→F transition at about 574 nm, which is the strongest for BSBF: Eu at 370 nm excitation and for BSBF: Eu, Tb, Ce at 300 nm and 370 nm excitations. No evidence of Tb→Eu energy transfer was found for BSBF: Eu, Tb, Ce. The PL spectra of BSBF: Eu at 77 and 300 K are similar with CIE chromaticity coordinates of (0.617; 0.378) at 300 nm excitation and (0.634; 0.359) at 395 nm excitation and low correlated color temperature which implies application prospects in the field of lightning. Due to the high intensity of D→F Eu transition at 370 nm excitation, the BSBF: Eu emission is yellow-shifted.