Effect of Zr4+ and Si4+ substitution on the luminescence properties of CaMoO4:Eu3+ red phosphors

A series of intense red emitting phosphors, Ca0.8-x Zr (x) Mo1-x Si (x) O-4:0.2Eu(3+) (x = 0.025, 0.05, 0.075, 0.1) that could be effectively excited in the UV region was prepared by conventional high temperature solid state reaction route. Structural, morphological and photoluminescence properties of the prepared samples were studied in detail. The incorporation of Zr4+ and Si4+ ions in CaMoO4 lattice maintained the powellite crystal structure. Luminescence properties were optimized for 7.5 mol% of Zr4+ and Si4+ concentration. Emission intensities improved more than twice in comparison with CaMoO4:Eu3+. Life times of the prepared samples improved and the quantum efficiency enhanced to similar to 39 %. The improvement in emission intensity and quantum efficiency is explained in terms of the local distortion around the Eu3+ ions resulting in improved absorption in the UV region. The CIE color co-ordinates of the red emission were in agreement with the values of the standard red phosphors providing potentiality to be used in phosphor converted (pc) white LEDs.