Color-tunable luminescence of Eu3+ in LaF3 embedded nanocomposite for light emitting diode

Eu3+-doped transparent nanocomposite of SiO2–Al2O3–NaF–LaF3 was fabricated by melt-quenching and subsequent heating. X-ray diffraction and transmission electron microscopy analyses evidenced that hexagonal LaF3 nanocrystals were homogeneously precipitated among the aluminosilicate glass matrix. The distribution of Eu3+ ions in the nanocomposite was investigated by energy dispersive X-ray spectroscopy, photoluminescence and time-resolved luminescence spectra. The nanocomposite exhibited intense blue and green emissions originating from the 5D1,2,3 levels of Eu3+ incorporated in the low-phonon-energy LaF3 nanocrystals, and red emission corresponding to the Eu3+:5D0 → 7FJ (J = 0, 1, 2, 3, 4) transitions, under the excitation of single wavelength light at 394 nm. By adjusting the Eu3+ doping content, various luminescent colors, including perfect white light, were easily tuned through cross relaxation processes between Eu3+ ions. The results suggest that the Eu3+-doped transparent nanocomposite could be potentially applicable as a white-light-emitting material under UV chip excitation.