Luminescence enhancement and site-dependent energy transfer of Ba5(B2O5)2F2: Ce3+/Tb3+/Na+ phosphors

Abstract Optical materials composed of Ba5-3(p+q)/2CepTbq(B2O5)2F2 and Ba5-(p+q+r)CepTbqNar(B2O5)2F2 (p = 0, 0.05, q = 0, 0.2, r = 0, 0.05, 0.2, 0.25) were prepared through solid-state reaction. X-ray diffraction patterns confirmed that single-phase phosphors contained monoclinic space group with appropriate index and peak positions. The particle sizes of the phosphors, which were characterized using scanning electron microscopy, were enhanced when Na+ ions were co-doped into the phosphors. The three-dimensional structure of the Ba5(B2O5)2F2 host contained three irregular Ba2+-centered polyhedrons connected to B2O7 clusters. Moreover, the excitation and emission spectra and Gaussian deconvolution of the phosphors were monitored. The enhanced photoluminescence excitation and emission spectra of Ba5(B2O5)2F2:Tb3+ were observed when the Ce3+ and Na+ ions were co-doped. The energy-transfer mechanism from Ce3+ to Tb3+ in the intense green Ba4.5Ce0.05Tb0.2Na0.25(B2O5)2F2 phosphors based on the Ba(1) and Ba(2)(3) sites of the luminescent Ce3+ center with the desired Commission Internationale de l’Eclairage coordinates was investigated. The color rendering index, correlated color temperature, and Commission Internationale de l’Eclairage coordinates were measured for the Ba4.5Ce0.05Tb0.2Na0.25B4O10F2 phosphor using a 365 nm-LED chip.