Nèel temperature variation of CoxNi1−xFe2O4 nanoparticles

CoxNi1−xFe2O4 (x=0.1, 0.3, 0.5) nanoparticles were synthesized by the PVA Sol–Gel method, and all the samples were found to be single phase spinel by powder X-ray diffraction measurements. High temperature Mössbauer spectra were recorded by a Mössbauer spectrometer. Temperature dependence of hyperfine magnetic fields of two magnetic sextets indicates a “two Nèel temperatures” phenomenon in Co0.3Ni0.7Fe2O4 and Co0.5Ni0.5Fe2O4, which has been further demonstrated by the magnetic thermo-gravimetric analysis (MTGA).