Superparamagnetic Transition and Local Disorder in CuFe2O4 Nanoparticles
arXiv:1302.5876 · doi:10.1016/S0965-9773(98)00133-0
Abstract
We present X-ray diffraction (XRD), Mössbauer spectroscopy (MS) and d.c. magnetization measurements performed on ball-milled CuFe2O4 samples. The average particle size <d> was found to decrease to the nanometer range after t=15 min of milling. Room temperature Mössbauer data showed that the fraction of particles above the blocking temperature TB increases with milling time, and almost complete superparamagnetic samples are obtained for <d> = 7(2) nm. Magnetization measurements below TB suggest spin canting in milled samples. The values of saturation moment mu_S reveal that site populations are slightly affected by milling. Mössbauer resonant intensities are accounted for on the basis of local disorder of Fe3+ environments, and the development of sample inhomogeneities of CuxFe3-xO4 composition.
18 pages, 5 figures