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| Naji, M. |
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| Motta, Antonella |
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| Aletan, Dirar |
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| Mohamed, Tarek |
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| Ertürk, Emre |
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| Taccardi, Nicola |
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| Kononenko, Denys |
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| Petrov, R. H. | Madrid |
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| Alshaaer, Mazen | Brussels |
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| Bih, L. |
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| Casati, R. |
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| Muller, Hermance |
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| Kočí, Jan | Prague |
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| Šuljagić, Marija |
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| Kalteremidou, Kalliopi-Artemi | Brussels |
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| Azam, Siraj |
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| Ospanova, Alyiya |
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| Blanpain, Bart |
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| Ali, M. A. |
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| Popa, V. |
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| Rančić, M. |
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| Ollier, Nadège |
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| Azevedo, Nuno Monteiro |
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| Landes, Michael |
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| Rignanese, Gian-Marco |
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Gnutek, P.
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Topics
Publications (2/2 displayed)
- 2009Modeling local structure using crystal field and spin Hamiltonian parameters: The tetragonal Fe<inf>K</inf><sup>3+</sup>-O<inf>I</inf><sup>2-</sup> defect center in KTaO<inf>3</inf> crystalcitations
- 2008Low symmetry aspects inherent in EMR studies of the orthorhombic to monoclinic structural phase transition in the hexagonal form of barium titanate BaTiO<inf>3</inf>doped by Fe<sup>3+</sup>ionscitations
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article
Low symmetry aspects inherent in EMR studies of the orthorhombic to monoclinic structural phase transition in the hexagonal form of barium titanate BaTiO<inf>3</inf>doped by Fe<sup>3+</sup>ions
Abstract
<p>Electron magnetic resonance (EMR) studies reveal different spectroscopic properties of transition ions doped in the two crystallographically different forms of barium titanate: cubic (normal) c-BaTiO<sub>3</sub> and hexagonal polymorph h-BaTiO<sub>3</sub>. Recent comparative analysis of EMR data helped to solve the controversy concerning the disparate zero-field splitting (ZFS) parameters for Fe<sup>3+</sup> ions in c-BaTiO<sub>3</sub>. This paper deals with the low symmetry aspects inherent in EMR studies of the orthorhombic to monoclinic structural phase transition in h-BaTiO<sub>3</sub> doped by Fe <sup>3+</sup> ions. Pertinent spin Hamiltonian notations and choices of axis systems are clarified. The second- and fourth-rank ZFS parameters determined by EMR and the second-rank ones computed using a superposition model for the Fe<sup>3+</sup> ions in h-BaTiO<sub>3</sub> are reanalyzed. The available ZFS parameters are presented in a well-defined axis system and in a unified way to ensure meaningful comparison. Pertinent transformations of ZFS parameters are carried out using the package CST. Simulations of the low symmetry ZFS parameters are carried out to assess the role of monoclinic and triclinic ZFS terms and to investigate the low symmetry aspects arising with lowering of temperature during the orthorhombic to monoclinic structural phase transition in Fe<sup>3+</sup>:h-BaTiO<sub>3</sub>. The procedure for analyzing experimental and theoretical ZFS parameters for transition ions at monoclinic and triclinic symmetry sites proposed here enables a better understanding of the low symmetry aspects involved. This study suggests the need to extend superposition model analysis to the fourth-rank ZFS terms for Fe<sup>3+</sup> centers in h-BaTiO<sub>3</sub>. © 2008 IOP Publishing Ltd.</p>