Ionic-liquid-assisted synthesis of YF3 with different crystalline phases and morphologies

YF3 with different crystalline phases and morphologies have been prepared via a facile hydrothermal route assisted by imidazolium ionic liquids 1-butyl-3-methylimidazolium tetrafluoroborate (C4mimBF4) or 1-butyl-3-methylimidazolium hexafluorophosphate (C4mimPF6). The microstructures and morphologies of YF3 particles were characterized by X-ray powder diffraction, X-ray photoelectron spectra (XPS), transmission electron microscopy (TEM), high resolution electron microscopy (HRTEM) and field emission scanning electron microscopy (FESEM). Cubic and orthorhombic YF3 were selectively synthesized by adjusting the molar ratio of the reagents and using C4mimBF4 as the fluoride source, while only orthorhombic YF3 was obtained using C4mimPF6, indicating that the crystalline phases and morphologies of the products were significantly influenced by fluoride source and reaction media.