Energy transfer, optical properties and thermal stability of Ce3+, Tb3+ activated apatite-type Ca8NaGd(PO4)6F2 phosphors

Abstract A novel color tunable phosphor was developed by a high-temperature solid-state reaction route with apatite-type Ca8NaGd(PO4)6F2 (CNGF) as matrix for the doping with Ce3+ and Tb3+ ions. The crystal structures were studied by XRD and Rietveld refinement, which clarified the structural parameters and the occupation of doped ions in crystal lattice. The luminescent intensity of Tb3+ ions was significantly improved by the energy transfer from Ce3+ to Tb3+ ions. According to the luminescence spectra and fluorescence decay curves of CNGF: Ce3+, Tb3+, a possible energy transfer mechanism was proposed. Fluorescent paper was prepared by binding the CNGF: Ce3+, Tb3+ phosphor particles with bacterial cellulose, and the morphology and luminescence properties of the paper were investigated. These results demonstrate that the obtained CNGF: Ce3+, Tb3+ is a promising green phosphor candidate for solid-state lighting and anti-counterfeiting applications.