Photoluminescence Properties of Red-Emitting Mn~(2+)-Activated CaAlSiN_3 Phosphor for White-LEDs

摘要

Mn~(2+)-doped CaAlSiN_3 phosphors have been prepared by a solid-state reaction method at high temperature and the solubility of Mn~(2+) in the host lattice as well as their photoluminescence properties were investigated. In CaAlSiN3, not only Ca~(2+) sites, but also Al~(3+) sites can be substituted by Mn~(2+) ions. CaAlSiN_3 : Mn~(2+) absorbs blue light in the spectral range of 440-460 nm, and exhibits a broad band emission in the wavelength range of 475-750 nm, which can be ascribed to the ~4T_1(~4G) → ~6A_1 (~6S) transition of Mn~(2+) located at two different sites in CaAlSiN_3. The emission bands at lower energy (15,950 cm~(-1) or 627 nm) and higher energy (18,250 cm~(-1) or 548 nm) are assigned to the Mn~(2+) locating at the Al site (Mn_(Al)) and Ca site (Mn_(Ca)), respectively with energy transfer from Mn_(Ca) to Mn_(Al). In addition, the integral luminescence intensity only decreases to about 94% at 150°C of the value at 50°C, which is of great interest for the applications of white-LEDs.