Unusual Ce3+ luminescence and Ce3+ → Tb3+ energy transfer behavior in strontium lithium borate SrLiB9O15

•SrLiB9O15:Ce3+/Tb3+ phosphors were studied for the first time.•Ce3+ ions occupy two different sites (Ce I and Ce II) in SrLiB9O15 crystal.•Ce3+ ions substitute Sr2+ sites and interstitial sites simultaneously.•Energy transfer behavior from Ce3+ to Tb3+ is confirmed.•The energy transfer occurs from Ce II to Tb3+ in this case.

Ce3+ and Tb3+ ions are important activators for various phosphors, but no detailed study has been performed on SrLiB9O15 crystal. Ce3+- and Ce3+/Tb3+-doped SrLiB9O15 phosphors were synthesized by using a standard high temperature solid-state technique. The phase purity and optical properties of the prepared samples are investigated by XRD, excitation and emission spectra. The unusual luminescence properties of Ce3+ activator, the Ce3+ site occupying and Ce3+ → Tb3+ energy transfer behavior are discussed.