Mass synthesis of nanocrystalline spinel ferrites by a polymer-pyrolysis route

Nanocrystalline MeFe2O4 (Me = Mn, Ni and Zn) spinel ferrites have been synthesized by polymer-pyrolysis method. The pyrolysis behaviors of the polymeric precursors prepared via in situ polymerization of metal salts and acrylic acid are analyzed by use of simultaneous thermogravimetric and differential thermal analysis (TG-DTA). Then, the structural characteristics of the products are studied by powder X-ray diffraction (XRD), infrared spectroscopy (IR), transmission electron microscope (TEM) and electron diffraction (ED) pattern. The results revealed that the spinel ferrites have nano-sized morphology and good crystallinity even if calcined at moderate temperature like 500 °C for 3 h. The average sizes of nanocrystalline spinel ferrites range from 10 to 30 nm with narrow size distributions. Magnetic measurements at room temperature show that Mn, Ni and Zn ferrites with the small coercivity and remanence exhibit soft magnetic behaviors. The spinel ferrites (MnFe2O4 and NiFe2O4) obtained here show higher saturation magnetization than the corresponding spinel ferrites produced by other methods such as conventional ceramic and wet chemical route.