Thermal stable La2Ti2O7:Eu3+ phosphors for blue-chip white LEDs with high color rendering index

High concentration Eu3+ doped La2Ti2O7 phosphor with good crystallinity was prepared via solid-state method. This phosphor can emit intense red light with a peak around 612 nm corresponding to the 5D0 → 7F2 transitions of Eu3+. The luminescent intensity excited at 465 nm, which corresponds to the wavelength of InGaN-based LEDs, is comparable with the intensity excited at 396 nm. The emission intensity increased with increasing Eu3+ concentration up to 30 mol%, and then decreased due to the concentration quenching. The White LED (WLED) fabricated by coating a mixture of Y3Al5O12:Ce3+ and La2Ti2O7:Eu3+ onto a blue InGaN chip showed higher color rendering index than the WLED fabricated by coating Y3Al5O12:Ce3+(Y3Al5O12:Ce3+-WLED). This phosphor also has excellent thermal stability, and the luminous intensity can remain 75.46% when it was heated to 200°. By optimizing the Eu3+ concentration and calcination temperature, we demonstrated that La2Ti2O7:Eu3+ was a promising red phosphor under blue light (465 nm) for high-power commercial Y3Al5O12:Ce3+-WLEDs.

Research highlightsLa2Ti2O7:Eu3+phosphors were synthesized by a solid state reaction method, which have good thermal stability and strong luminescent intensity. Because this phosphor was efficiently excited by 465 nm, it can well match the blue LED Chips. The WLED fabricated by coating a mixture of Y3Al5O12:Ce3+ and La2Ti2O7:Eu3+ onto blue InGaN chip showed higher color rendering index than the Y3Al5O12:Ce3+-WLED and its good thermal stability can meet the demand of high-power LEDs.