Color-tunable, single phased BaLa2−x−yZnO5: xBi3+, yEu3+ phosphors with efficient energy transfer under ultraviolet excitation

Color-tunable phosphors BaLa2−x−yZnO5: xBi3+, yEu3+ (0≤x≤0.2, 0≤y≤0.5) were prepared through solid state reaction. The structure, luminescence properties and the energy transfer from Bi3+ to Eu3+ are investigated in detail. Bi3+ in BaLa2ZnO5 emits blue light in a broad band peaking at 412 nm, which is attributed to the transition from excited state 3P1 to ground state 1S0 under the excitation of near-ultraviolet (N-UV) light with a wavelength of 312 nm. Eu3+ in BaLa2ZnO5 emits red light. The co-doping of small amount of Bi3+ into Eu3+ doped BaLa2ZnO5 can realize brighter red light attributed to the energy transfer from Bi3+ to Eu3+. The color-tunable emission can be found by adjusting the amount of Eu3+ in BaLa1.99−yZnO5: 0.01Bi3+, yEu3+ phosphors. The decay curves of Bi3+ were measured to understand the energy transfer processes better, and further the energy-transfer probability and efficiency from Bi3+ to Eu3+ on the Bi3+ concentration were calculated.