Effects of Cr-doping on the morphology and optical properties in Zn2GeO4 (ZGO) nanorods prepared by hydrothermal method

The undoped Zn₂GeO₄ nanorods and the Cr-doped Zn₂GeO₄ nanorods were successfully prepared by the hydrothermal method. The structure, the optical characteristics properties of nano phosphor powders were studied by X-ray diffraction, ultraviolet-visible diffuse reflectance spectroscopy, photoluminescence spectroscopy, FESEM. The results indicated that Cr ions substituted for Ge ions and the Cr doping expanded for the unit cell of the crystal lattice. The band gap energy found to be decreased with increasing Cr doping concentration. At a wavelength of 250-320 nm excitation, Cr³⁺ doped Zn₂GeO₄ phosphors showed bluishwhite emission at 510 nm. The concentration of Cr³⁺ ions in Zn₂GeO₄:Cr³⁺ played important roles in the evolution of the length of nanorods, photoluminescence intensity and quality of nano crystal. This result contributed optimization of Cr³⁺ doped nano phosphors with 5% mol. The possible mechanism of substitution of ion Cr in Zn₂GeO₄ nano crystalline has also been discussed.