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Böttcher, R.; Klimm, C.; Michel, D.; Semmelhack, H.‐C.; Völkel, G.; Gläsel, Hans‐Jürgen; Hartmann, E.

doi:10.1103/physrevb.62.2085

Cited by 105 publications

(51 citation statements)

References 30 publications

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“…Over the past decades, the NSM parametrization has been refined by applying the method to many examples of paramagnetic centers in perovskite-type crystals. Examples include iron-doped PbTiO 3 , SrTiO 3 and BaTiO 3 [9,10], LiTaO 3 [11], as well as chromium-modified PbTiO 3 [12] and manganese in BaTiO 3 [13].…”

Section: ••mentioning

confidence: 99%

Iron-oxygen vacancy defect association in polycrystalline iron-modifiedPbZrO3antiferroelectrics: Multifrequency electron paramagnetic resonance and Newman superposition model analysis

et al. 2006

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The Fe 3+ center in ferroelectric PbTiO 3 together with an oxygen vacancy forms a charged defect associate, oriented along the crystallographic c-axis.Its microscopic structure has been analyzed in detail comparing results from a semi-empirical Newman superposition model analysis based on finestructure data and from calculations using density functional theory.Both methods give evidence for a substitution of Fe 3+ for Ti 4+ as an acceptor center. The position of the iron ion in the ferroelectric phase is found to be similar to the B-site in the paraelectric phase. Partial charge compensation is locally provided by a directly coordinated oxygen vacancy.Using high-resolution synchrotron powder diffraction, it was verified that lead titanate remains tetragonal down to 12 K, exhibiting a c/a-ratio of 1.0721.

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Section: ••mentioning

confidence: 99%

Iron-oxygen vacancy defect association in polycrystalline iron-modifiedPbZrO3antiferroelectrics: Multifrequency electron paramagnetic resonance and Newman superposition model analysis

et al. 2006

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“…(9), that corresponds to paraelectric phase, resonance frequency in shell and core regions can be written respectively as ω 0ps = ω 0c + η/R (η is proportional to surface tension and spin-phonon coefficient) and ω 0pc = ω 0c with ω 0c value close to resonance frequency in the bulk paraelectric phase of cubic symmetry. In general case one can expect the appearance of two separate lines, namely for core and for shell region.…”

Section: Spectra Of Magnetic Resonancesmentioning

confidence: 99%

“…[9][10][11]). The main advantage of these methods is their ability to study local properties of the solids that is very important for nanomaterials, namely nanograin ceramics, nanoparticle powders, thin films.…”

Section: Introductionmentioning

confidence: 99%

Size Effects in Radiospectroscopy Spectra of Ferroelectric Nanopowders

et al. 2005

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The theoretical and experimental investigation of ferroelectric nanopowders is performed. The manifestation in radiospectroscopy spectra of size driven ferroelectric-paraelectric phase transition at some critical particle average size R = R c was the main goal of the consideration. In theoretical part the size effect for the materials with ferroelectric tetragonal phase at room temperature and cubic paraelectric phase was considered allowing for the spontaneous polarization inhomogeneity inside a particle and distribution of particle sizes. In ESR the transformation of the spectra from tetragonal symmetry to cubic symmetry lines with decrease in nanoparticle sizes was calculated. The method of Rc value extraction from the ratio of the different symmetry lines intensities in the absorption spectra was proposed. Measurements of Fe 3+ ESR spectra in nanopowder of BaTiO3 were carried out at room temperature. The samples were prepared by rate-controlled method with different particle sizes, which depend on annealing temperature. The decrease in intensity of tetragonal symmetry ESR lines of Fe 3+ and appearance of cubic symmetry line with asymmetry of the shoulders was observed with the average sizes decrease with complete disappearance of tetragonal spectrum at R ≤ 40 nm. The comparison of the theory with experiment was carried out. The theory fits experimental data pretty good. The value of critical size R c ≈ 40 nm was extracted from ESR data. The asymmetry and broadening of right hand side shoulder of ESR cubic symmetry line was shown to be related to contribution of paramagnetic centers in the vicinity of the particles surface with lower than cubic symmetry. The deconvolution of the cubic line allowed to show that this region size is about 3 nm.

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“…This material basis allowed for a considerable widening the methodological framework for studying size effects on ferroelectric properties by means of electron paramagnetic resonance (EPR) measurements [2,3]. In doing so, a rather detailed idea could be derived of the bulk-shell structure of such a BaTiO 3 nanoparticle and its temperature and size driven transitions from tetragonal ferroelectric phase into the cubic paraelectric one where the sample yields EPR data comprehended by a cubic Hamiltonian, speaking of a remote counter charge.…”

mentioning

confidence: 99%

Multi‐frequency EPR studyof Cr³⁺ doped lead titanate (PbTiO₃) nanopowders

Erdem

Böttcher

Semmelhack

et al. 2003

Physica Status Solidi (b)

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In our multi-frequency EPR study of Cr 3+ doped PbTiO 3 nanopowder samples with varying mean particle size, three paramagnetic Cr 3+ centres (C1, C2, C3) with different axial fine structure (FS) parameters are identified, with one of them (C1) being compatible with former literature measurements on bulk and ceramics samples carried out in the X band. The superposition model by Newman and Urban was applied to translate the FS data into local displacements inside the distorted oxygen octahedra of the PbTiO 3 lattice. When going to nanopowder samples with mean particle size below a critical value, other than the centre C1 are no longer detectable. Instead, a new one (C4) appears, testifying a pronounced size effect.

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Size effect inMn2+-dopedBaTiO3nanopowders obse

Cited by 105 publications

References 30 publications

Iron-oxygen vacancy defect association in polycrystalline iron-modifiedPbZrO3antiferroelectrics: Multifrequency electron paramagnetic resonance and Newman superposition model analysis

Iron-oxygen vacancy defect association in polycrystalline iron-modifiedPbZrO3antiferroelectrics: Multifrequency electron paramagnetic resonance and Newman superposition model analysis

Size Effects in Radiospectroscopy Spectra of Ferroelectric Nanopowders

Multi‐frequency EPR studyof Cr³⁺ doped lead titanate (PbTiO₃) nanopowders

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Size effect inMn2+-dopedBaTiO3nanopowders obse

Cited by 105 publications

References 30 publications

Iron-oxygen vacancy defect association in polycrystalline iron-modifiedPbZrO3antiferroelectrics: Multifrequency electron paramagnetic resonance and Newman superposition model analysis

Iron-oxygen vacancy defect association in polycrystalline iron-modifiedPbZrO3antiferroelectrics: Multifrequency electron paramagnetic resonance and Newman superposition model analysis

Size Effects in Radiospectroscopy Spectra of Ferroelectric Nanopowders

Multi‐frequency EPR studyof Cr3+ doped lead titanate (PbTiO3) nanopowders

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Multi‐frequency EPR studyof Cr³⁺ doped lead titanate (PbTiO₃) nanopowders