Structural investigation of composite phases Ba1 + x [(NaxMn1 – x)O3] with x approx. 2/7, 5/17 and 1/3; exotic Mn4.5+ valence
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Pascal Roussel
Abstract
Structural models are proposed for three composite compounds of chemical formula Ba1 + x [(NaxMn1 – x)O3] (x approx. 2/7, 5/17 and 1/3) by single crystal X-ray diffraction; superspace formalism is used to obtain an unified description of the three phases. The modulation affecting Ba atoms can be easily designed but the competition “occupational/displacive” modulations relating to the Mn/Na metallic columns were particularly difficult to modelize. However, the large amplitude of the displacive modulation affecting the oxygen atoms (approx. ±0.7 Å) in comparison with that observed for related compounds (approx. ±0.3 Å) makes it a direct consequence of the Na+ alkali insertion inside the trigonal prisms. Owing to this insertion, the Mn atoms exhibit, in the three phases, an “exotic” oxidation state of about +4.5. In addition, even if the sequence between face sharing MnO6 octahedra and NaO6 trigonal prisms can be analytically deduced from the x value, it is clear that the Na/Mn contrasts play in favour of its accurate determination through the XRD single crystal refinement.
© by Oldenbourg Wissenschaftsverlag, München, Germany
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Articles in the same Issue
- Zeitschrift für Kristallographie - Crystalline Materials
- Structural investigation of composite phases Ba1 + x [(NaxMn1 – x)O3] with x approx. 2/7, 5/17 and 1/3; exotic Mn4.5+ valence
- Crystal structures of 4-PhCOS-5-RS-1,2-dithiole-3-thione (R = Me and PhCH2), 4,5-(MeS)2-1,2-dithiole-3-thione and 3,4,5-(MeS)3-1,2-dithiolium iodide
- Structures of (pyrazinecarbonyl)hydrazones of substituted benzaldehydes: supramolecular arrangements generated by various intermolecular contacts
- Two polymorphs of bis(4-benzoylthio-1,3-dithiole-2-thione)-5,5′-disulphide
- Synthesis, spectral, thermal and structural characterization of hexa-aqua copper(II)] 3-(4-nitrophenyl)-2-phenylpropenoate
- [Tb(pyrazinecarboxylic acid)3(H2O)2] · 6n H2O: Synthesis, structure and photoluminescence