Host lattice materials in the system Ca3N2-AlN-Si3N4 for white light emitting diode

New host lattice materials whose red phosphors for white LEDs have been investigated in the ternary system Ca3N2-AlN-Si3N4, just as Ca2Si5N8 and CaSiN2: Eu were found in the binary system Ca3N2-Si3N4. A new red phosphor of CaAlSiN3: EU which is effectively excited by blue-GaN and near UV-GaInN LED chips has been synthesized at 1600 degrees C for 2 h and subsequently at 1800 degrees C for 2 h under nitrogen pressure of 1 MPa. The host-compound has an orthorhombic structure with the space group Cmc2(1) (No. 36), which is isotypic with LiSi2N3 and NaSi2N3. The red phosphor showed the emission peak around 650 nm which was assinged to 5d -> 4f of EU2+ ion, and its color coordinates were estimated to be 0.667 and 0.327. The optimum concentration of Eu2+ ion was 1.6 mol%. The phosphor also had a high chemical stability, high quantum output, and especially a good thermal property compared to the other phosphors, Ca2Si5N8: Eu2+ and CaSiN2: Eu2+. CaAlSiN3: Eu2+ maintained 83% of the initial efficiency above 150 degrees C. (c) 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.