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Gläsel, Hans‐Jürgen; Hartmann, E.; Hirsch, D.; Böttcher, R.; Klimm, C.; Michel, D.; Semmelhack, H.‐C.; Hormes, J.; Rumpf, Holger

doi:10.1023/a:1004533926099

Cited by 45 publications

(29 citation statements)

References 13 publications

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“…7 Our preparation route of PbTiO 3 nanopowders may be briefly described by the following reactions: In the first step, lead titanium methacrylate is obtained as a monomeric metallo-organic precursor from lead(II) oxide PbO, titanium(IV) isopropoxide Ti(O-C 3 H 7 ) 4 and methacrylic acid CH 2 C(CH 3 )-COOH in boiling chloroform. Then, the solid-phase polymerization and the concomitant pyrolysis proceed simultaneously at temperatures above 200°C.…”

Section: Methodsmentioning

confidence: 99%

Size effects in chromium-doped PbTiO3 nanopowders observed by multi-frequency EPR

et al. 2005

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A multi-frequency (X, Q, and W band) electron paramagnetic resonance (EPR) study of Cr-doped PbTiO3 micro- and nanopowder samples was performed. Three Cr3+ centres were identified in tetragonal phase samples with different axial Zero Field Splitting (ZFS) parameters, C1, C2, and C3. The centre C1 is similar to that observed in previous X-band crystal and ceramic sample measurements. The superposition model by Newman and Urban was applied to translate the ZFS data into local displacements inside the distorted oxygen octahedra of the PbTiO3 lattice. In the tetragonal phase, only the centre C1 was observed. The powder spectra were fitted using a spin-Hamiltonian in which a Gaussian distribution of ZFS terms, characterized by a mean value D and distribution width deltaD, was assumed. The variation of D and deltaD with mean particle size was determined. A critical particle size, d(cr), exists, particles smaller than this size remain in the cubic phase for all temperatures, there is a size-driven tetragonal-to-cubic phase transition. Particles with d < d(cr) were found to give a new Cr3+ centre spectrum, C4, consisting of a single line with an isotropic g-factor, so allowing the cubic phase content to be quantified. Further, temperature-dependent EPR measurements were made, which allowed the variation in Curie temperature with mean particle size to be determined.

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Section: Methodsmentioning

confidence: 99%

Size effects in chromium-doped PbTiO3 nanopowders observed by multi-frequency EPR

et al. 2005

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“…Partially oxidized PANI and its oligomers display an additional absorption at around 712 nm associated with the quinoid (oxidized) units [22]. These peaks are characteristic of the PANI emeraldine base [23,24] and indicate that nanostructured PANI composites are stabilized in the emeraldine base redox state. The peak at 315 nm is attributed to π -π* transition of benzoid rings and the peak at 712 nm is attributed to the charge transfer excitation of the quinoid structure.…”

Section: Uv-vis Propertiesmentioning

confidence: 99%

Spectroscopic, Kinetic Studies of Polyaniline-Flyash Composite

Khan¹,

Khare²,

Baruah³

et al. 2011

ACES

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Polyaniline-fly ash (PANI-FA) composites were prepared by oxidative polymerization of aniline with fly ash in presence of ammonium persulphate (APS). The PANI-FA composites were prepared with different concentrations of fly ash to aniline ratio. The composites, so prepared, were characterized by UV-vis spectroscopy, Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). The thermal stability was studied by TGA and total weight loss of PANI, FA and PANI-FA composites having FA composition of 0.02%, 0.1%, 0.5% and 1.0% were found to be 82%, 39%, 67% 65%, 62% and 61%, respectively. The UV-vis spectroscopy of the PANI-FA polymeric composite shows absorption maxima at 315 and 350 nm (due to π-π* transition of the benzenoid rings), and 578-712 nm (due to charge transfer excitations of the quinoid structure), which are characteristic of emeraldine base. FTIR spectra of the PANI-FA composite is similar to that of pure polyaniline (PANI) but with the bands for C = N, C = C and C-N shifted to lower wave numbers, i.e., 1585, 1494, 1327 and 1113 cm −1 due to strong interaction of Fe 2 O 3 and PANI matrix. SEM shows the complexation of metal oxide with emaraldine base of PANI, significantly changing the aggregate state of polymeric molecular chain.

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“…1 Introduction In previous work, by the application of the original and flexible combined polymerisation and pyrolysis (CPP route), manganese(II) doped barium titanate (BaTiO 3 :Mn 2+ ) nanopowders were prepared in a wide mean particle range (from 10 nm up to 2 µm) [1]. 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].…”

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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Cited by 45 publications

References 13 publications

Size effects in chromium-doped PbTiO3 nanopowders observed by multi-frequency EPR

Size effects in chromium-doped PbTiO3 nanopowders observed by multi-frequency EPR

Spectroscopic, Kinetic Studies of Polyaniline-Flyash Composite

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

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Untitled

Cited by 45 publications

References 13 publications

Size effects in chromium-doped PbTiO3 nanopowders observed by multi-frequency EPR

Size effects in chromium-doped PbTiO3 nanopowders observed by multi-frequency EPR

Spectroscopic, Kinetic Studies of Polyaniline-Flyash Composite

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

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Product

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