Local geometric and electronic structures and origin of magnetism in Co-doped BaTiO{sub 3} multiferroics

Journal Article · Thu May 07 00:00:00 EDT 2015 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4907182· OSTI ID:22410108

Phan, The-Long; Ho, T. A.; Manh, T. V.; Thang, P. D. ^[1]; Thanh, Tran Dang ^[2]; Lam, V. D. ^[3]; Dang, N. T. ^[4]

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1. Faculty of Engineering Physics and Nanotechnology, VNU-University of Engineering and Technology, Xuan Thuy, Cau Giay, Hanoi (Viet Nam)
2. Department of Physics, Chungbuk National University, Cheongju 361-763 (Korea, Republic of)
3. Institute of Materials Science, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet, Hanoi (Viet Nam)
4. 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

Related Subjects

75 CONDENSED MATTER PHYSICS
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