Controllable synthesis, shape evolution, and luminescence properties of uniform and well-dispersed NaEuF4 microcrystals through hydrothermal route

Sodium europium fluorides NaEuF4 microcrystals with uniform and well-dispersed shapes and dimensions have been prepared via a facile hydrothermal route using Na3Cit as the chelating ligand and shape modifier. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), selected-area electron diffraction (SAED), energy-dispersive X-ray (EDX) and photoluminescence spectra (PL) were taken to characterize the samples. A series of controlled experiments reveal that the trisodium citrate (Na3Cit) content, pH value of the initial solution, and reaction time have an indispensable role on the phase, size, and morphology of the as-prepared microcrystals. Based on the experimental results, the possible growth mechanism of the microcrystals prepared under different conditions was proposed. Moreover, we systematically investigated the luminescent properties of the as-prepared microcrystals with different morphologies obtained under different amounts of Na3Cit, which have potential application in the fields of color display, UV laser and biomedicine.