Controlled synthesis of EuPO4 nano/microstructures and core–shell SiO2@EuPO4 nanostructures with improved photoluminescence

Abstract

Cluster-like, flower-like and sphere-like EuPO₄ nano/microstructures and uniform core–shell SiO₂@EuPO₄ nanostructures have been controllably synthesized by the hydrothermal route and co-precipitation method, respectively. The as-synthesized products are characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS) and infrared spectroscopy (IR). The possible formation mechanism of the as-synthesized products is proposed. The photoluminescence properties demonstrate that the locations of the strongest peaks of nano/microstructured EuPO₄ and core–shell nanostructured SiO₂@EuPO₄ are different. In the emission spectrum of the core–shell SiO₂@EuPO₄ nanostructures, the ⁵D₀ → ⁷F₂ transition is much stronger than the ⁵D₀ → ⁷F₁ transition, indicating that Eu³⁺ ions occupy low symmetry sites in the EuPO₄ lattice. Furthermore, the core–shell SiO₂@EuPO₄ nanostructures have stronger emission intensity than the flower-like and sphere-like EuPO₄ nano/microstructures.