Up-conversion photoluminescence emissions of CaMoO4:Pr3+/Yb3+ powder

CaMoO4:Pr3+/Yb3+ powder was successfully synthesized by a facile hydrothermal method. X-ray diffraction (XRD) patterns of samples confirmed tetragonal structure and morphology and sizes were confirmed by scanning electron microscopy (SEM) analyses. Particles consisted of regular micro-spheres with uniform sizes, the diameter of each sphere lay in the range of 3 to 4 mu m. The up-conversion photoluminescence emission and its concentration dependence were investigated under infrared excitation at 980 nm. All the UC micro-particles exhibited the typical blue, green and red emissions. Dominant blue emissions originated from P-3(0)-> H-3(4) and intense red emissions originated from P-3(0)-> H-3(4) transitions, and they both belonged to two-photon excitation processes in CaMoO4:Pr3+/Yb3+ powder. The optimum doping concentrations of Pr3+ and Yb3+ for the highest UC luminescence were 0.1 mol.% and 16 mol.%, respectively. The possible up-conversion mechanisms were discussed in detail. It was found that the UC emission could be well controlled from blue to green to white color by adjusting the concentration of Pr3+ ions in CaMoO4:Pr3+/Yb(3+)microcrystal. So it is a candidate material for solid-state lasers, biological imaging, solar cells, and optical communications.