(Zn, Mg)(2)GeO4:Mn2+ submicrorods as promising green phosphors for field emission displays: hydrothermal synthesis and luminescence properties

(Zn1-x-yMgy)(2)GeO4: xMn(2+) (y = 0-0.30; x = 0-0.035) phosphors with uniform submicrorod morphology were synthesized through a facile hydrothermal process. X-Ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), photoluminescence (PL), and cathodoluminescence (CL) spectroscopy were utilized to characterize the samples. SEM and TEM images indicate that Zn2GeO4:Mn2+ samples consist of submicrorods with lengths around 1-2 mu m and diameters around 200-250 nm, respectively. The possible formation mechanism for Zn2GeO4 submicrorods has been presented. PL and CL spectroscopic characterizations show that pure Zn2GeO4 sample shows a blue emission due to defects, while Zn2GeO4:Mn2+ phosphors exhibit a green emission corresponding to the characteristic transition of Mn2+ (T-4(1) -> (6)A(1)) under the excitation of UV and low-voltage electron beam. Compared with Zn2GeO4:Mn2+ sample prepared by solid-state reaction, Zn2GeO4:Mn2+ phosphors obtained by hydrothermal process followed by high temperature annealing show better luminescence properties. In addition, codoping Mg2+ ions into the lattice to substitute for Zn2+ ions can enhance both the PL and CL intensity of Zn2GeO4:Mn2+ phosphors. Furthermore, Zn2GeO4:Mn2+ phosphors exhibit more saturated green emission than the commercial FEDs phosphor ZnO:Zn, and it is expected that these phosphors are promising for application in field-emission displays.