Luminescent properties of near-infrared-emitting Cr3+-activated beta-Ca3(PO4)2

In this work, a series of Cr3+-doped (3-tricalcium phosphate ((3-TCP) powders was synthesized by a wet co- precipitation method. It was shown that the dissolution of Cr3+ ions in the (3-TCP crystal structure is limited, resulting in the formation of a Cr2O3 secondary phase at higher substitution levels. The room-temperature and temperature-dependent photoluminescence excitation spectra, emission spectra, and photoluminescence decay curves of the samples were studied. Thermally stimulated luminescence, and afterglow decay spectral measurements were performed as well. All the synthesized materials exhibited broadband photoluminescence in the near-infrared region, ranging from approximately 680 to 900 nm, with a maximum centered at 760 nm. The strongest emission was detected for the sample with a doping level of 0.1 mol% Cr3+. Moreover, for the (3-TCP: 0.1 mol% Cr3+ sample, the afterglow after irradiation with X-rays can be detected for at least 8 h.