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- Title
Complementary Studies of Phase Formation During Fabrication of FeCo Nanoparticles by Mechanical Alloying.
- Authors
Manh, Do; Tung, D.; Phong, L.; Phuc, Nguyen; Phong, P.; Jutimoosik, Jaru; Yimnirun, Rattikorn
- Abstract
Fe-Co nanoparticles were prepared by mechanical alloying in air with various milling times from 0 h to 10 h and annealing temperatures in the range from 773 K to 973 K. The combined use of both conventional x-ray diffraction (XRD) and synchrotron x-ray absorption spectroscopy (XAS) techniques allowed us to obtain accurate data on the phase formation and the oxidation state of the materials. XRD patterns reveal a secondary phase of FeO that is present in as-milled samples and those annealed in Ar + H (5%) at temperatures of up to 600°C. This secondary phase disappeared for annealing temperatures of over 700°C. Meanwhile, analyses of Fe K-edge x-ray absorption near-edge structure (XANES) and extended x-ray absorption fine structure (EXAFS) spectra clearly showed that the local structure around Fe of all samples were of a bcc structure and had the oxidation state of +0. Most importantly, the ratio of bcc and hcp structures was also extracted from the Co K-edge XANES and the measured K-weighted EXAFS spectra of the alloyed Fe-Co samples. Moreover, magnetization measurements at room temperature indicated that the saturation magnetization ( M) increased with increasing milling time and annealing temperature. While the former behavior is assigned to the Fe-Co alloy formation, we believe the effects of reducing the oxidation of the annealed samples to be the major cause of the enhanced M. The dependence of coercivity ( H) on milling time and annealing temperature was also investigated and discussed.
- Subjects
MECHANICAL alloying; MAGNETIC nanoparticles; ANNEALING of metals; X-ray diffraction; X-ray absorption
- Publication
Journal of Electronic Materials, 2016, Vol 45, Issue 5, p2501
- ISSN
0361-5235
- Publication type
Article
- DOI
10.1007/s11664-016-4392-x