Effect of Y3+ on the local structure and luminescent properties of La3−xYxSi6N11:Ce3+ phosphors for high power LED lighting

Abstract

A series of Ce³⁺-activated La_3−xY_xSi₆N₁₁ yellow phosphors were synthesized by high temperature solid-state reaction; their structures and luminescent properties were systematically investigated. The results of structural and spectral characterization showed that with the increase of Y³⁺ replacing La³⁺ in La_3−xY_xSi₆N₁₁:Ce³⁺ (0 < x ≤ 0.9), the space group remains P4bm but with Y³⁺ occupying two crystallographic sites in different ratio, while the emission spectra exhibit a red-shift from 535 nm to 552 nm. Moreover, the thermal quenching properties of La_2.86−xY_xSi₆N₁₁:0.14Ce³⁺ exhibit somewhat of a decrease with the increase of x value, but still remains at 95% (x = 0.9) of the initial emission intensity measured at 200 °C. In addition, the light quality is significantly improved by direct packaging with a blue LED chip. The above results indicate that La_3−xY_xSi₆N₁₁:Ce³⁺ may be a promising phosphor for high power white-light LEDs.