The doping site analysis and control of Eu³⁺ in ZnO:Eu crystal lattice

A new effective and convenient method is put forward to accurately analyze and control the doping sites of Eu³⁺ in ZnO:Eu nanocrystal. By analyzing the drift of XRD peaks, the splits of laser-stimulated fluorescence peak, intensity variation of E₂ Raman scattering peaks and lattice distortion from HRTEM, the position that Eu³⁺ ions occupy in host lattice is accurately analyzed. There generally exists the symmetry broken regularity for disordered doped system such as ZnO:Eu — it is that Eu³⁺ is inclined to occupy the position with low symmetry for equilibrium growth crystal. At high annealing temperature, the crystallographic symmetry of Eu³⁺ is reduced from C_3v to C₂, which fully evidences that Eu³⁺ ions are separated out of host lattice. In the same time, the doping position of the Eu can be completely controlled by controlling annealing temperature. In the low symmetrical crystal field, 612 nm fluorescence peak splits to 4 splits, and the peak width of the strongest one is only about 4 nm. This nanomaterial with extremely narrow luminescence will have intensively potential applications in the fields of high quality light source with high contrast control and high signal to noise ratio such as fluorescence probe in high resolution bioimaging.