Synthesis and photoluminescence properties of Mn2+ doped Ca1-xSrxCN2 phosphors prepared by a carbon nitride based route

Mn2+ doped Ca1-xSrxCN2 phosphors were synthesized by a solid-state reaction in only 1 h under NH3 atmosphere at 700 degrees C from doped calcium carbonate and carbon nitride as precursors. The samples were characterized by powder X-ray diffraction, scanning electron microscopy and their diffuse reflectance and luminescence properties were investigated in order to evaluate the potential of such systems as red phosphors. All pure and well-crystallized Mn2+ doped samples exhibit broad red emission around 680 nm when excited at 270 nm at room temperature corresponding to the T-4(1g)((4)G) -> (6)A(1g)(S-6) transition. Maximum emission in CaCN2: Mn is obtained for Mn2+ content of 4 %mol and is stable up to 343 K and then shows a 20% decrease at 393 K. Finally, the progressive substitution of Sr2+ for Ca2+ evidences a solid solution domain between CaCN2 and beta-SrCN2 with continuous increase of the crystal lattice dimensions. However, such substitution has no impact on the wavelength emission but leads to a decrease of the luminescence efficiency of the phosphor.