EDTA-mediated hydrothermal synthesis of NaEu(MoO4)2 microrugbies with tunable size and enhanced luminescence properties

Abstract

Tetragonal NaEu(MoO₄)₂ with rugby-like microstructures were successfully synthesized by a hydrothermal method in an EDTA-mediated process. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM) techniques were employed to characterize the products in detail. It was found that the amount of EDTA, reaction temperature and pH value are important parameters affecting the morphology, crystallinity and size of the final product, respectively. The possible formation mechanism for the microrugbies was proposed on the basis of a series of time-dependent experiments. This facile method was also successfully applied in the synthesis of NaSm(MoO₄)₂ and NaGd(MoO₄)₂ microrugbies. The photoluminescence (PL) properties of NaEu(MoO₄)₂ microrugbies were strongly dependent on the size and crystallinity. The calcined products displayed excellent luminescence behaviors with a high color purity and have the potential to be applied in LED devices. The possible reasons for the difference in the relative intensities of luminescence are also discussed in detail.