Structural, magnetic and microstructural study of Sr2Ni2Fe12O22

The substitution of divalent nickel ions in Sr-Y type hexaferrite is considered to be important for the enhancement of its magnetic properties. The nickel substituted Sr-Y hexaferrite with chemical formula Sr2Ni2Fe12O22 is prepared using analar grade reactants in the proper molar ratio by well-known solid-state reaction method. Structural characterization of the compound has been carried out from X-ray powder pattern. The compound is in single hexagonal phase without the traces of the unreacting ambiguous reflections. The lattice parameters are a=5.881 A and c=43.52 A. The real density of the compound is calculated from helium picnometry, which agrees with the theoretically calculated value of X-ray density. The surface morphology was studied by scanning electron microscopy. Clearly hexagonal particles are observed with faster crystallization rate. The average particle size is also estimated. The compound is studied magnetically using Gouy's method. The results show the compound is ferrimagnetic at room temperature with transition temperature TC=698 K. The high value of TC is as expected due to the presence of Ni2+ and Fe3+ ions in the compound. From the paramagnetic behaviour, the Curie molar constant is worked out. Electrical conductivity measurement approves the dual conduction mechanism in the compound. The compound shows semiconducting behaviour with room temperature resistivity 8.935x109 Ω cm