Enhanced photoluminescence in CaMoO4:Eu3+ by Gd3+ co-doping

We have studied the luminescence property of CaMoO4:Eu3+. The emission peaks at 590 (D-5(0)-> F-7(1)) and 613 nm (D-5(0)-> F-7(2)) for Eu3+ are observed after excitation at 266 nm (i.e. Mo-O charge transfer band). The peak intensity of the latter dominates over the former indicating an asymmetric environment of Eu3+ in EuO8 polyhedron or parity mixing. Luminescence intensity increases significantly with co-doping of Gd3+. This is ascribed to energy transfer from Mo O/Gd3+ to Eu3+. Luminescence intensity increases with annealing up to 900 degrees C due to the extent of decrease of non-radiative rates. Very high asymmetric values (A(21)) of 12-16 are found indicating a red emitter. As-prepared samples are dispersible in polar solvents like water, ethanol, methanol, dimethyl sulfoxide (DMSO) and ethylene glycol (EG); and among them, optimum luminescence is found in methanol. Polymer film shows red emission. The quantum yields of as-prepared 2 and 10 at% Gd3+ co-doped CaMoO4:Eu3+ under 277 nm (UV excitation) are 21 and 80%, respectively.