Photoluminescence properties of red-emitting Mn2+-activated CaAlSiN3 phosphor for white-LEDs

Mn2+-doped CaAlSiN3 phosphors have been prepared by a solid-state reaction method at high temperature and the solubility of Mn2+ in the host lattice as well as their photoluminescence properties were investigated. In CaAlSiN3, not only Ca2+ sites, but also Al3+ sites can be substituted by Mn2+ ions. CaAlSiN3 : Mn2+ 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 4T1 (4G) ¿ 6A1 (6S) transition of Mn2+ located at two different sites in CaAlSiN3. 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 Mn2+ locating at the Al site (MnAl) and Ca site (MnCa), respectively with energy transfer from MnCa to MnAl. 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.