A high quenching content red-emitting phosphor based on double perovskite host BaLaMgSbO₆for white LEDs

Warm white LEDs with a high color rendering index and a low correlated color temperature have become a tendency. In this regard, more effective red-emitting phosphor has been optimally selected. A series of double perovskites BaLa_1-xEu_xMgSbO₆(x = 0.05, 0.1, 0.3, 0.5, 0.7, 0.9 and 1) phosphors have been successfully synthesized by solid-state method, which can generate strong red-emitting for its high quenching content. The crystal structure symmetry and the ordering degree of B-site atoms were discussed by powder X-ray diffraction, GSAS structural refinement and the Raman modes. The Eu³⁺ions were located in the A-site of the crystal lattices, and the oxygen ions were arranged in cubic close packed together with cations at A-site. The ions at B-site were located at octahedral gaps. A weak magnetic dipole transition (⁵D₀-⁷F₁, 590 nm) and a strong electric dipole transition (⁵D₀-⁷F₂, 615 nm) existed in the emission spectra, indicating that the Eu³⁺ions were located in the A-site with low crystal symmetry in the BaLaMgSbO₆lattice. The distance between the luminescent centers could be increased in the crystal structure, attributing to the obtain of a high quenching content. The coordinates gradually shifted toward to the ideal red light (0.67, 0.33) with an increasing R/O value. The thermal quenching performance indicated an excellent thermal stability. In a summary, host BaLaMgSbO₆has been designed, and the excellent optical performance exhibits great promise applications in white LEDs.