| In this paper, Spinel ferrites of Ni and Co magnetic nanoparticles with various morphologies and size were controllably fabricated by simple hydrothermal method. The structure, morphology, and magnetic properties of the reaction products were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), high resolution electron microscopy (HRTEM), and vibrating sample magnetometer (VSM), respectively. The paper includes three parts. In the first part, size and shape controllable NiFe2O4nanooctahedrons were successfully synthesized without any surfactant by employing hydrothermal method using divalent metal salt of nickel and trivalent iron in alkaline solution of NaOH. The obtained particles were a single spinel structure. We discussed effects of concentration of NaOH and reaction time on the reaction products. The results revealed that concentration of NaOH solutions would have greater effect on size of products, but have a little effect to the morphologies. In the second part, CoFe2O4nanoparticles were successfully synthesized by using divalent metal salts cobalt and trivalent iron in alkaline solution of NaOH. The concentration of NaOH and amount of surfactant used in experiment both have a significant effect on the morphology of products and as well as their sizes. We studied the magnetic properties of samples with different sizes and the magnetization and coercivities of samples both increases with increasing of samples sizes. In the third part, nano scale magnetic CoxNi1-xFe2O4particles hydrothermally synthesized by using three metal nitrates as starting materials in alkaline solution of NaOH. The magnetic properties of products get controlled by the molar ratio of Co2+and Ni2+in synthesis of magnetic CoxNi1-xFe2O4nanoparticles. Based on the experimental observations and corresponding literatures, the magnetic characteristics of as-synthesized nanoparticles were analyzed and discussed. |
PDF Full Text Request