Controllable synthesis of Zn2GeO4:Eu nanocrystals with multi-color emission for white light-emitting diodes

Nanorod-like Zn2GeO4 and diverse Zn2GeO4:xEu nanostructures were controllably synthesized via a surfactant-free hydrothermal route. Detailed composition and morphology were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM). The influence of Eu3+-doping on the phase and size transition of Zn2GeO4 nanocrystals was investigated, and a possible Zn2GeO4:xEu crystal growth mechanism, which is ascribed to hetero-valence ion doping, is proposed. Photoluminescence (PL) spectra indicate that Zn2GeO4:xEu phosphors give both the bluish-white emission from the Zn2GeO4 host and orange-red emission of Eu3+ ions. The morphologies of calcined Zn2GeO4:xEu were studied and their PL properties were also investigated. The results suggested that the emission of both the Zn2GeO4 host and Eu3+ ions can be adjusted via tuning the concentration of Eu3+-doping, excitation wavelengths and calcination schedules of the Zn2GeO4:xEu nanocrystals. Therefore, Zn2GeO4:Eu nanocrystals with multi-color as well as white light emission displayed a potential application for white light-emitting diodes.