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

Abstract

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.