0000000000564278

AUTHOR

I. O. Troyanchuk

showing 3 related works from this author

Neutron diffraction studies of structural and magnetic properties of niobium doped cobaltites.

2009

Neutron powder diffraction studies of the structural and magnetic properties of the La(1-x)Sr(x)Nb(y)Co(1-y)O(3) solid solutions (x = 0.2, 0.5; y = 0, 0.075, 0.1) have been performed. Substitution of Co(2+) by Nb(5+) prevents the formation of Co(4+) and leads to stabilization of the Co(3+) ions in the high- or intermediate-spin state. This is accompanied by the significant change of the Co-O bond length as well as Co-O-Co bond angle in the CoO(6) octahedron. The obtained data are in agreement with the negative sign of the magnetic exchange interactions Co(3+)-O-Co(3+) in a relatively wide range of the Co-O-Co bond angles. Diamagnetic dilution by the niobium ions prevents long-range magnetic…

Bond lengthCrystallographyMagnetizationMolecular geometryMagnetoresistancechemistryMagnetic momentNeutron diffractionNiobiumchemistry.chemical_elementDiamagnetismGeneral Materials ScienceCondensed Matter PhysicsJournal of physics. Condensed matter : an Institute of Physics journal
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Short- and long-range order in La1−xSrxCoO3 and La1−xBaxCoO3

2008

Abstract The short- and long-range order correlations of the crystal structure in the distorted perovskites La 1− x Sr x CoO 3 and La 1− x Ba x CoO 3 (0.0⩽ x ⩽0.5) have been studied by the neutron powder diffraction (NPD) and the Co K-edge X-ray absorption spectroscopy (XAS) measurements. The results of XAS and NPD indicate a local distortion around the Co 3+ ions in LaCoO 3 at room temperature. The substitution of the La 3+ ions by the Sr 2+ (Ba 2+ ) ions leads to a gradual increase of the Co–O–Co angle and is accompanied by an increase of the mean square relative displacement (MSRD) of the Co–O bond. These results correlate with an increase of the oxygen amplitude vibration in the directi…

X-ray absorption spectroscopyAbsorption spectroscopychemistry.chemical_elementGeneral ChemistryCrystal structureCondensed Matter PhysicsOxygenIonCrystalCrystallographyAmplitudechemistryPerpendicularGeneral Materials ScienceJournal of Physics and Chemistry of Solids
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Interpretation of the Co K-edge EXAFS in LaCoO3 using molecular dynamics simulations

2011

Abstract Temperature dependent (180–400 K) Co K-edge EXAFS spectra from perovskite-type rhombohedral ( R 3 ¯ c ) LaCoO 3 have been successfully interpreted using a combination of classical NVT molecular dynamics (MD) and ab initio multiple-scattering (MS) theory. The method allowed us to account entirely for thermal disorder and to interpret reliably the contribution from the coordination shells beyond the first one into the total EXAFS spectrum taking into account many-body effects. The best agreement between experimental and configuration-averaged EXAFS spectra was obtained for pure ionic La 3+ and partially ionic Co 1.35+ and O 1.45− charges indicating the mixed ionic-covalent character …

Extended X-ray absorption fine structureChemistryAb initioIonic bondingThermodynamicsGeneral ChemistryTrigonal crystal systemCondensed Matter PhysicsSpectral lineInterpretation (model theory)CrystallographyMolecular dynamicsK-edgeGeneral Materials ScienceSolid State Ionics
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