Local geometric and electronic structures and origin of magnetism in Co-doped BaTiO{sub 3} multiferroics
- Faculty of Engineering Physics and Nanotechnology, VNU-University of Engineering and Technology, Xuan Thuy, Cau Giay, Hanoi (Viet Nam)
- Department of Physics, Chungbuk National University, Cheongju 361-763 (Korea, Republic of)
- Institute of Materials Science, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet, Hanoi (Viet Nam)
- Institude of Research and Development, Duy Tan University, Da Nang (Viet Nam)
We have prepared polycrystalline samples BaTi{sub 1−x}Co{sub x}O{sub 3} (x = 0–0.1) by solid-state reaction. X-ray diffraction and Raman-scattering studies reveal the phase separation in crystal structure as changing Co-doping content (x). The samples with x = 0–0.01 are single phase in a tetragonal structure. At higher doping contents (x > 0.01), there is the formation and development of a secondary hexagonal phase. Magnetization measurements at room temperature indicate a coexistence of paramagnetic and weak-ferromagnetic behaviors in BaTi{sub 1−x}Co{sub x}O{sub 3} samples with x > 0, while pure BaTiO{sub 3} is diamagnetic. Both these properties increase with increasing x. Analyses of X-ray absorption spectra recorded from BaTi{sub 1−x}Co{sub x}O{sub 3} for the Co and Ti K-edges indicate the presence of Co{sup 2+} and Co{sup 3+} ions. They locate in the Ti{sup 4+} site of the tetragonal and hexagonal BaTiO{sub 3} structures. Particularly, there is a shift of oxidation state from Co{sup 2+} to Co{sup 3+} when Co-doping content increases. We believe that the paramagnetic nature in BaTi{sub 1−x}Co{sub x}O{sub 3} samples is due to isolated Co{sup 2+} and Co{sup 3+} centers. The addition of Co{sup 3+} ions enhances the paramagnetic behavior. Meanwhile, the origin of ferromagnetism is due to lattice defects, which is less influenced by the changes caused by the variation in concentration of Co{sup 2+} and Co{sup 3+} ions.
- OSTI ID:
- 22410108
- Journal Information:
- Journal of Applied Physics, Vol. 117, Issue 17; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
SUPERCONDUCTIVITY AND SUPERFLUIDITY
BARIUM COMPOUNDS
COBALT IONS
CONCENTRATION RATIO
CRYSTAL DEFECTS
DOPED MATERIALS
ELECTRONIC STRUCTURE
FERROMAGNETISM
MAGNETIZATION
PARAMAGNETISM
POLYCRYSTALS
RAMAN SPECTROSCOPY
TEMPERATURE RANGE 0273-0400 K
TITANATES
TITANIUM IONS
VALENCE
X-RAY DIFFRACTION
X-RAY SPECTRA