Mössbauer study of nanocrystalline cubic CuFe2O4 synthesized by precipitation in polymer matrix

Nanocrystalline cubic CuFe2O4 was prepared at very low temperature by co-precipitation of metal ions in a polymer matrix. The sample annealed at 373 K showed very small clusters of cubic CuFe2O4 with an average size of 5 nm. The cubic phase showed excellent stability without undergoing any phase transition. The Mössbauer spectra of the annealed samples with a range of particle sizes were recorded at room temperature and 77 K. The samples annealed below 673 K showed paramagnetism and were unable to experience ordered magnetic structure even at 77 K. The sample annealed at 673 K with an average particle size of 12 nm showed superparamagnetic relaxation at room temperature and hyperfine structure at 77 K.