Development of a cyan blue-emitting BaLa(BO):Ce,Tb phosphor for use in dental glazing materials: color tunable emission and energy transfer.

The Ce/Tb doped BaLa(BO) phosphors were synthesized by a conventional solid state reaction method. The synthesized phosphor samples are a single phase of BaLa(BO) and showed angular-shaped fine grains with average particle size from 5 μm to 10 μm. The BaLa(BO):Ce phosphors showed an asymmetric broad blue emission under excitation at 365 nm and the BaLa(BO):Tb phosphors exhibited typical green emission assigned to the 4f-4f transition of Tb under excitation at 254 nm. Under near-UV (365 nm) excitation, BaLa(BO):Ce,Tb phosphors showed both a blue emission band and green emission peaks due to Ce and Tb, respectively. By optimizing the composition, cyan-blue emission with high color purity (CIE chromaticity coordinate values = 0.2557 and = 0.3839) was obtained for the BaLa(BO):0.05Ce,0.03Tb 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, BaLa(BO):Ce,Tb phosphors, and low 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).