Synthesis and characterization of NiFe₂O₄ nanoparticles and nanorods

Highly ordered single crystalline nickel ferrite (NiFe₂O ₄) nanorods have been successfully synthesized by a polymer assisted co-precipitation method using polyethylene oxide (PEO) as a capping and a polymer structure directing reagent. In this synthesis, the addition of high concentration of PEO seems to play an important role in the formation, size and shape control of the nanorods. Powder X-ray diffraction (XRD) and selected area electron diffraction (SAED) exhibit that the obtained nanorods can be indexed to single crystalline inverse spinel with Fd3m space group. The synthesized NiFe₂O₄ products were characterized in terms of their structural and magnetic properties. The morphological investigations using high resolution scanning electron microscopy (HRSEM) and transmission electron microscopy (TEM) reveal that the grown products are rod-like structure with the diameters in the range of 60-65 nm and length of 142-147 nm. The coercivity of prepared nanorods with high concentration of PEO reached as high as 904.46 Oe at room temperature (300 K), superior to that of nanoparticles obtained with low concentration of PEO. Hence, it can be used for high frequency electronics and gas sensing applications. On the basis of these experimental results, possible influence mechanisms in the growth processes are discussed.