Ultrasound induced strain in ultrasmall CoFe2O4@polyvinyl alcohol nanocomposites

Cobalt ferrite/Polyvinyl alcohol (PVA) nanocomposites were prepared with and without ultrasonic treatment by co-precipitation technique, characterized by X-ray diffraction (XRD), Vibrating sample magnetometer (VSM), Fourier transform infrared spectroscopy (FT-IR) and Transmission Electron Microscopy (TEM). The obtained results revealed that ultrasound irradiation induces strain in the structure and increases the magnetic anisotropy energy of the 7 nm magnetic nanoparticles (MNPs). The diffraction peak broadening and shift to lower angle due to the lattice strain were analyzed by means of Williamson-Hall (W-H) method. TEM images also show that ultrasound irradiated sample contain nano-crystallite cobalt ferrite which have completely dispersed and embedded in PVA matrix. These ultrasmall MNPs whit nonzero coercivity are promising for high density data storage devices.