The synthesis and luminescent properties of Eu3+ doped Li5La3Ta2O12 garnet phosphor with enhanced red emission and thermally stable

Abstract

The Li5La3Ta2O12 garnet is one of the important electrolytes in lithium-ion batteries. The red emission of Li5(La1-xEux)3Ta2O12 phosphor was synthesized due to solid-phase method with the precursor calcining at 850 ​°C for 4 ​h. The crystal structure, particle morphology, band gap and fluorescent properties were systematically discussed by the various instruments of XRD, FE-SEM, UV–vis, PLE/PL, spectroscopy and fluorescence decay analysis. Under the optimal excitation wavelength at 293 ​nm and 393 ​nm, the PL spectra of Li5(La1-xEux)3Ta2O12 phosphor displayed the vivid red emission at 613 ​nm (the 5D0→7F2 transition of Eu3+) with the different concentration of Eu3+. The higher concentration of Eu3+ replacing La3+ led to smaller cell constants and the low symmetry of the (La/Li)O8 dodecahedra, and the bandgap decreased with the doping of Eu3+ increasing. The lifetimes of Li5(La1-xEux)3Ta2O12 (x ​= ​0.05–0.3) phosphors slightly decreased. The underlying mechanisms were thoroughly investigated and elucidated. The thermal stabilities of Li5(La1-xEux)3Ta2O12 phosphor phosphors was investigated in detail, which show excellent red light emission in LED device applications. The Li5(La1-xEux)3Ta2O12 phosphor with low synthetic temperature, excellent fluorescence performance and good thermal stability is expected to be widely used in light and displays area.