Zahra Abdi - Department of Materials Science and Engineering, Sharif University of technology, Tehran, Iran
Adrine Malek Khachatourian - Department of Materials Science and Engineering, Sharif University of technology, Tehran, Iran
Ali Nemati - Department of Materials Science and Engineering, Sharif University of technology, Tehran, Iran

A novel magnetically separable NiFe۲O۴@Ti-doped ZnO nanosphere was synthesized using the heterogeneous nucleation of Ti-doped ZnO nanoparticles on NiFe۲O۴ polycrystalline nanospheres by hydrothermal method. Structural and microstructural properties of synthesized polycrystalline nanospheres were studied by X-ray diffraction (XRD), Fourier-transform infrared spectra (FTIR), Field emission scanning electron microscopy (FESEM) with an energy-dispersive X-ray spectrometer (EDX), and Transmission electron microscopy (TEM). The effect of calcination on optical and magnetic properties is also investigated. The optical properties of synthesized nanoparticles were investigated using UV-vis spectroscopy which shows the absorption peak in the visible region. The band gap energy of pure ZnO, Ti-doped ZnO, and NiFe۲O۴@Ti-doped ZnO before and after calcination was calculated ۳.۲۱ eV, ۲.۹۲ eV, ۲.۴۴ eV, and ۲.۰۴ eV, respectively. A vibrating sample magnetometer (VSM) was employed to study magnetic features that the saturation magnetization (Ms) of NiFe۲O۴ and NiFe۲O۴@Ti-doped ZnO non-calcined and calcined was obtained ۶۳.۶ emu/g, ۲۱.۳ emu/g, and ۱۵.۳ emu/g, respectively. Hence, the results represented that the calcination of NiFe۲O۴@Ti-doped ZnO nanosphere improved the optical properties and reduced the band gap energy. However, NiFe۲O۴ combination with nonmagnetic matrix and calcination of NiFe۲O۴@Ti-doped ZnO nanoparticles decrease the saturation magnetization (Ms) value and response to the external magnetic field.

Magnetic Nanoparticles, heterogeneous nucleation, hydrothermal method, band gap engineering, saturation magnetization