Peculiar β-Li2TiO3: Eu3+ red light emitting dominated by electric dipole transition: Asymmetric lattice point regulation and luminescence performance

Abstract

In order to obtain red phosphor with high color purity, β-Li2TiO3: Eu3+ dominated by electric dipole transition was prepared by the hydrothermal method. Eu3+ doping concentration (< 0.5 mol%) and calcination time (> 12 h) can regulate the phase purity, supercell development, asymmetric lattice point configuration and the luminescence performance. Under excitation at 394 nm, β-Li2TiO3: Eu3+ emits narrow band 618 nm red light due to that Eu3+ replaces Li+ at the relatively active Li1 position, and the 5D0 → 7F2 electric dipole transition dominates. Calcined at 600 °C for 36 h with Eu3+ doped concentration of 0.5 mol%, the luminescence performance of β-Li2TiO3: Eu3+ is superior, of which the lifetime is 0.64 ms, the color coordinates x = 0.63, y = 0.37, the color temperature of 987 K, the color rendering index of 82, and the red color purity of 99.7%. The electric dipole transition line intensity parameters Ω2 and Ω4 are 8.01 × 10−20 cm2 and 0.62 × 10−20 cm2, respectively, yielding Ω2/Ω4 of 12.9. The fluorescence branch ratio of 5D0 → 7F2 is 82.9%, and the quantum efficiency can reach 92%, which is superior within similar materials.