Synthesis of lanthanide fluoride nanoparticles of varying shape and size

Yttrium fluoride nanoparticles of varying crystallinity, shape, and size are prepared by precipitation in reverse microemulsions of water in cyclohexane stabilized with polyoxyethylene isooctylphenyl ether. YF3 particles obtained by the classical microemulsion method are found to be monodisperse amorphous spheres, with controllable diameters between 6 and 50 nm. Particles of the same material obtained by a relatively minor variation of this method are found to be monocrystalline. Typically, mixtures of monodisperse regular hexagonal and triangular single crystals are observed. The size of the crystalline particles can be varied between about 25 and 350 nm. The formation of single crystals can be attributed to the slower incorporation of the precipitant into the micelles when introduced in this fashion.