A new type of charge compensating mechanism in Ca5(PO4)3F:Eu3+ phosphor

The X-ray powder diffraction, reflectance, photoluminescence, photoluminescence excitation and ESR spectra of Ca5(PO4)3F:Eu3+ phosphor have been studied. Three distinct variants of calcium substitutional Eu3+-sites have been observed in this host and the charge compensating species related to each of these sites has been identified. It is noted that the host related trace impurities those have prospects of acting as charge compensator, and the reaction environment that exists during the preparation of the material, greatly influence the preferential substitution of different Ca2+-sites by the Eu3+ ions. It is also noted that the charge compensating species in a suitable case, takes part in the photophysical process of luminescence of the Eu3+.