New Deep-Blue-Emitting Ce-Doped A 4- m B n C 19+2 m X 29+ m (A = Sr, La; B = Li; C = Si, Al; X = O, N; 0 ≤ m ≤ 1; 0 ≤ n ≤ 1) Phosphors for High-Color-Rendering Warm White Light-Emitting Diodes.

A new sialon EuLiSiAlON has been discovered via the single-particle diagnosis approach. Its crystal structure (space group P3m1) was solved and refined from single crystal X-ray diffraction data. It has the interesting feature of two types of disorder at the Eu2 site: positional disorder (Eu2a/Eu2b) and substitutional disorder with (Si/Al)(O/N)). The structure is generalized to the formula ABCX (A = Sr, La, Eu, Ce; B = Li; C = Si, Al; X = O, N; 0 ≤ m ≤ 1; 0 ≤ n ≤ 1), of which SrLiSiAlON (Sr-sialon, m = 0.41, n = 1) and LaSrLiSiAlON (LaSr-sialon, m = 0.40, n = 1) are two examples that have been obtained as a single phase powder. Sr-sialon:Eu and LaSr-sialon:Eu both show blue to yellow emission, depending on Eu concentration, while Sr-sialon:1%Ce shows a deep-blue emission band centered at 422 nm with a full width at half maximum (FWHM) of 80 nm and an IQE of 80% (λ = 355 nm). The latter phosphor has very good thermal stability of both emission intensity and color. A white LED containing the newly discovered Sr-sialon:5%Ce as blue phosphor component shows excellent color rendering indices (Ra = 96 and R12 = 97) with a correlated color temperature (CCT) of 4255 K. It indicates that Sr-sialon:Ce is a highly promising deep-blue phosphor for illumination grade white LEDs.