Development of a cyan blue-emitting Ba3La2(BO3)4:Ce3+,Tb3+ phosphor for use in dental glazing materials: color tunable emission and energy transfer

The Ce3+/Tb3+ doped Ba3La2(BO3)4 phosphors were synthesized by a conventional solid state reaction method. The synthesized phosphor samples are a single phase of Ba3La2(BO3)4 and showed angular-shaped fine grains with average particle size from 5 μm to 10 μm. The Ba3La2(BO3)4:Ce3+ phosphors showed an asymmetric broad blue emission under excitation at 365 nm and the Ba3La2(BO3)4:Tb3+ phosphors exhibited typical green emission assigned to the 4f–4f transition of Tb3+ under excitation at 254 nm. Under near-UV (365 nm) excitation, Ba3La2(BO3)4:Ce3+,Tb3+ phosphors showed both a blue emission band and green emission peaks due to Ce3+ and Tb3+, respectively. By optimizing the composition, cyan-blue emission with high color purity (CIE chromaticity coordinate values x = 0.2557 and y = 0.3839) was obtained for the Ba3La2(BO3)4:0.05Ce3+,0.03Tb3+ phosphor, and the internal quantum efficiency of the phosphor at the excitation wavelength of 365 nm is estimated to be 50%. The dental glazing paste prepared by mixing organic binder, Ba3La2(BO3)4:Ce3+,Tb3+ phosphors, and low Tg glass was successfully vitrified when it was heated at 600 and 700 °C, and showed high chemical stability of the luminescence properties in acidic aqueous solution (pH = 4).