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

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 changesmore » caused by the variation in concentration of Co{sup 2+} and Co{sup 3+} ions.« less
Authors:
; ; ;  [1] ;  [2] ;  [1] ;  [3] ;  [4] ;  [5]
  1. Department of Physics, Chungbuk National University, Cheongju 361-763 (Korea, Republic of)
  2. Faculty of Engineering Physics and Nanotechnology, VNU-University of Engineering and Technology, Xuan Thuy, Cau Giay, Hanoi (Viet Nam)
  3. (Viet Nam)
  4. Institute of Materials Science, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet, Hanoi (Viet Nam)
  5. Institude of Research and Development, Duy Tan University, Da Nang (Viet Nam)
Publication Date:
OSTI Identifier:
22410108
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 117; Journal Issue: 17; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
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