Effect of Ce3+ Co-doping on GdPO4:Tb3+ Nanoparticles: Photoluminescence and Energy Transfer Studies

Low temperature synthesis of Tb3+-doped GdPO4 nanoparticles sensitized with Ce3+ (Ce3+ = 0, 3, 5, 7 and 10 at.%) have been reported. Ethylene glycol was used as capping agent as well as reaction medium at 160 ºC. The as-prepared particles crystallized in a monoclinic structure with an average crystallite size of 25-46 nm. From the photoluminescence study, enhanced emission of Tb3+ with co-doping of Ce3+ was attributed to efficient energy transfer from the sensitizer to activator. The luminescence emission intensity increases upto 5 at.% of Ce3+ and then decreases. Less efficient energy transfer from sensitizer to the activator with increasing concentration of sensitizer may be attributed to critical concentration of Ce3+ with the host or dipole-quadrupole interaction amongst the Ce3+ ions. Moreover, presence of -OH group in the samples will make them a potential target for biological labeling and optical devices.