Crystallization of ZnO on crystalline magnetite nanoparticles in the presence of ultrasound radiation

Hollow ZnO hexagons 200 nm wide and 500 nm long filled with highly crystalline Fe₃O₄ particles were prepared by a sonochemical process. The seeds for the growth of the ZnO crystals, the magnetite particles, were coated with two surfactants, oleic acid and oleylamine. The magnetite nanoparticles had a diameter of 11.8 nm and a narrow size distribution. HR-TEM (High-Resolution TEM) measurements show that the magnetite nanoparticles are encapsulated inside the ZnO tube homogeneously. The embedded particles are also monodispersed and their size is reduced to 3.6 nm. Magnetization curves show that the ZnO tubes behave as a superparamagnetic material.