Influences of Ce3+ dosage, NH4Cl flux, and post-treatment on the structure and luminescence properties of Ce-activated La–Si–O–N for laser lighting

The emerging laser-driven phosphor-converted white laser diodes (w-LDs) demand highly efficient and thermally stable color converters. To this end, the Ce 3+ luminescence in the rekindled La–Si–O–N host, and the impacts of NH 4 Cl flux and post-processing are investigated systematically. On the basis of the XRD results, well crystalline Ce 3+ -doped La 5 Si 3 O 12 N and LaSiO 2 N are obtained at 1600 °C for 5 h and 1500 °C for 4 h, respectively. Impressively, the representative La 5 Si 3 O 12 N:0.04Ce 3+ and LaSiO 2 N:0.03Ce 3+ exhibit a broad excitation band from 240 nm to 400 nm, peaking at around 360 nm, which is well matched with emission from near-UV (n-UV) chip. Under excitation by a n-UV laser, the La 5 Si 3 O 12 N:0.04Ce 3+ and LaSiO 2 N:0.03Ce 3+ produce bright blue light in a wide emission band from 360 nm to 550 nm. The CIE chromaticity diagram reveals the tunability of the hue of these phosphors. The quenching temperature is determined to be 396 K and 429 K for La 5 Si 3 O 12 N:0.04Ce 3+ and LaSiO 2 N:0.03Ce 3+ respectively, indicating superior thermal stability. The addition of 3 wt% NH 4 Cl flux much enhances the emission intensity of both La 5 Si 3 O 12 N:0.04Ce 3+ and LaSiO 2 N:0.03Ce 3+ . Furthermore, the post-treatments markedly improve the luminescence properties by increasing the crystallinity , reducing the surface defect , and changing the morphology. Therefore, it is believed that the present work has promising applications in LD lighting and promoting the development of laser display.