Luminescence and stability of Tb doped CaF(2) nanoparticles

Luminescence properties of CaF(2):Tb(3+) nanoparticles were studied in order to investigate the effect of CaF(2) native defects on the photoluminescence dynamics of Tb(3+) ions. Incorporation of Tb ions into the CaF(2) host was confirmed by X-ray diffraction and X-ray photoelectron spectroscopy. Cross-relaxation energy transfer was observed from the photoluminescence spectra and decay curves upon excitation at 257 nm. However, the unusual long lifetime of the Tb(3+) ion as well as the decreasing trend of emission lifetime of the (5)D(3) level suggested the involvement of traps, which were further investigated by using temperature-dependent photoluminescence measurements, thermoluminescence and lifetime measurements at different wavelengths. This work highlights the critical role that the CaF(2) native defects play in the photoluminescence dynamics of Tb(3+) ions incorporated in a CaF(2) matrix. The sample doped with 10 mol% of Tb(3+) ions was found to be stable under prolonged 254 nm ultraviolet irradiation.