Characterization and magnetic phase resolution of CoFe_2O_4 nanocubes and nanospheres

摘要

Cobalt ferrite nanosamples are prepared by hydrothermal method and their structural and morphological analysis are conducted by varying hydrothermal reaction time. X-ray diffraction analysis at room temperature confirms the formation of pure phase sample. Samples with size varying from 9.4nm to 28nm were synthesized by varying reaction time from 6hr to 24hr. Both TEM and XRD results match regarding particle size. The particle size is found to increase with increase in reaction time and also an interesting morphology transition from nanospheres to nanocube is observed as reaction time is increased. Magnetic studies are done using VSM analysis at room temperature. Magnetic parameters of importance are extracted from the analysis and the contributions of different magnetization phases to the total magnetization are found using a program developed in python. Excellent fits are obtained for all three samples and from the M-H curve analysis, ferromagnetic and paramagnetic contributions to the magnetization are found. All samples show ferromagnetic and paramagnetic contributions. The nanocube is found to have 74.34% ferromagnetic contribution and 25.65% of Paramagnetic contribution whereas the nanospheres are found to be almost entirely ferromagnetic with 93.8% contribution and only 6.2 % of paramagnetic contribution.