Synthesis of ultradisperse NiFe2O4 spinel by thermal decomposition of citrate precursors and its magnetic properties

Peculiarities of synthesis of nanocrystalline NiFe2O4 powders by thermal decomposition of citrate precursors were investigated. It was found that the parameters of nanopowders are determined by the decomposition temperature and pH of the precursor media. The temperature and duration of the process of precursor decomposition are limiting factors for decrease of the grain size. An optimum relation between the limiting factors can be determined experimentally by variation of pH. Correlation between the synthesis parameters, particle size, and magnetic properties is discussed. It is shown that optimum magnetic and magnetostrictive properties were found for the bulk polycrystalline samples sintered using the powders obtained for pH 2.