Synthesis and photoluminescence of high color purity red-emitting BaLaLiTeO₆:Eu³⁺ phosphors

Red phosphors based on BaLaLiTeO₆ doped with Eu³⁺ were prepared by high temperature solid state method. The XRD patterns for the representative samples revealed its single phase structure and the scanning electron microscopes were studied to reveal the morphology and homogeneous distribution of particles with different size. In addition, the density of states and partial density of states of each element revealed that Ba-O and La-O groups are the main factors that determine the optical properties of the BaLaLiTeO₆. When emitted by 394 nm near-ultraviolet, all the samples emit bright red light near 618 nm because of ⁵D₀→ ⁷F₂ transition of Eu³⁺ ions. The optimal doping concentration of Eu³⁺ in BaLaLiTeO₆ is 0.20 and the mechanism of concentration quenching is the dipole-quadrupole interaction. Besides, the temperature-dependent emission spectra of BaLaLiTeO₆:0.2Eu³⁺ red sample were studied systematically and the thermal activation energy of the sample was 0.30 eV, indicating its good thermal stability. The lifetime of Eu³⁺ ions is in the millisecond level and the CIE chromaticity coordinate of BaLaLiTeO₆:0.2Eu³⁺ is (0.6436, 0.3535) with a high color purity of 99.4%, which is close to the standard of red chromaticity. To sum up, the BaLaLiTeO₆:Eu³⁺ phosphors are the hopeful red component applied in the white light illumination.