YF3 with different crystalline phases and morphologies have been prepared via a facile hydrothermal route assisted by imidazolium ionic liquids 1-butyl-3-methylimidazolium tetra fluoroborate(C(4)mimBF(4)) or 1-butyl-3-methylimidazolium hexafluorophosphate (C(4)mimPF(6)). 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 C(4)mimBF(4) as the fluoride source, while only orthorhombic YF3 Was obtained using C(4)mimPF(6), indicating that the crystalline phases and morphologies of the products were significantly influenced by fluoride source and reaction media. (C) 2008 Elsevier Ltd. All rights reserved.