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Local geometric and electronic structures and origin of magnetism in Co-doped BaTiO3 multiferroics

Phan, The Long and Pham, Duc Thang and T., A. Ho and T., V. Manh and Tran, Dang Thanh and V, D. Lam and N., T. Dang and S., C. Yu (2015) Local geometric and electronic structures and origin of magnetism in Co-doped BaTiO3 multiferroics. Journal Applied Physics, 117 .

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We have prepared polycrystalline samples BaTi1−xCoxO3 (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 BaTi1−xCoxO3 samples with x > 0, while pure BaTiO3 is diamagnetic. Both these properties increase with increasing x. Analyses of X-ray absorption spectra recorded from BaTi1−xCoxO3 for the Co and Ti K-edges indicate the presence of Co2+ and Co3+ ions. They locate in the Ti4+ site of the tetragonal and hexagonal BaTiO3 structures. Particularly, there is a shift of oxidation state from Co2+ to Co3+ when Co-doping content increases. We believe that the paramagnetic nature in BaTi1−xCoxO3 samples is due to isolated Co2+ and Co3+ centers. The addition of Co3+ 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 Co2+ and Co3+ ions. The-Long , P. D. Thang2, T. A. 1, T. V. Manh1, Tran Dang Thanh1,3, V. D. Lam3, N. T. Dang4 and S. C. Yu

Item Type: Article
Subjects: Engineering Physics
Divisions: Faculty of Engineering Physics and Nanotechnology (FEPN)
Depositing User: Ms. Cam Le Tran Thi
Date Deposited: 06 Jul 2016 06:33
Last Modified: 06 Jul 2016 06:35

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