Ultrasonic synthesis, characterization and formation mechanism of aggregated nanorings of EuF3

The aggregated nanorings of EuF3 were synthesized via ultrasonic irritation in aqueous solution. The products were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). XRD pattern proved that the crystalline phase of the EuF3 rings was hexagonal. The SEM and TEM images indicated that the as-prepared EuF3 nanocrystals had ring-like morphology and were aggregated by numerous small crystallites (about 10–15 nm in diameter); the outer diameter of the rings was in the range of 200–300 nm, while the inner diameter was in the range of 50–80 nm with a thickness of 30–40 nm. Moreover, the time-depend experiments were carried out to disclose the formation mechanism of the as-prepared ring-like nanostructures.