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Arilasita Retna,Utari,Purnama Budi 한국물리학회 2021 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.79 No.2
We report change in the structural and the magnetic properties of a gamma-irradiated sample of CoBi0.1Fe1.9O4 nanoparticles synthesized using the co-precipitation method. All samples were exposed to low doses of γ-radiation (i.e., 0, 100, 200, 400, and 800 Gy). The X-ray diffraction (XRD) evaluations indicated that all samples had a single-phase cubic spinel structure in space group Fd3m. The crystal size, lattice parameter, and other structural parameters of the irradiated CoBixFe2- xO4 nanoparticles were calculated based on the XRD data. The crystallite size is found to increase with increasing radiation dose. The stretching vibration modes of the absorption bands (v1 and v2) were observed in the Fourier transform infrared (FTIR) spectrum, thereby reconfirming that the metal oxide is realized a cobalt ferrite-based material. The change in the surface morphology was measured using scanning electron microscopy (SEM). Finally, the modified magnetic parameters (Hc, Ms, Mr) of the gamma-irradiated samples were determined from the M–H loop recorded at room temperature.
Retna Arilasita,Utari,Budi Purnama 한국물리학회 2019 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.74 No.5
This study aims to prepare strontium-substituted cobalt ferrite (Sr$_{0.1}$Co$_{0.9}$Fe$_2$O$_4$) nanoparticles by using a simple co-precipitation process followed by annealing at 300$^\circ$C--600$^\circ$C for 5 h. The Sr$_{0.1}$Co$_{0.9}$Fe$_2$O$_4$ nanoparticles thus obtained have a face-centred cubic (fcc) inverse-spinel crystalline structure with crystallite sizes in the range from 17.26 to 26.97~nm. The saturated magnetization of the nanoparticles increases with increasing annealing temperature. Furthermore, the transition from a multi-domain to a single-domain configuration is investigated from the viewpoint of the dependence of the crystallity on the coercive field.