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Charge Ordering (charge + ordering)
Selected AbstractsChemInform Abstract: Partial Charge Ordering in the Mixed-Valent Compound (Bi6O5) Rh83+Rh44+O24.CHEMINFORM, Issue 24 2008H. Mizoguchi Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Inhomogeneous surface electronic properties and charge ordering in epitaxial Fe3O4 films on MgO(001)PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 12 2007A. Subagyo Abstract We report scanning tunneling microscopy (STM) study of surface electronic properties and charge ordering of epitaxially grown magnetite, Fe3O4, (001) films exhibiting high density of antiphase domain boundaries (APBs). STM measurements using a W tip reveal surface termination at B-sites. Fe ions with a 0.3 nm periodicity, i.e., a single atomic distance are observed. Current imaging tunneling spectroscopy reveals the alternation of two kinds of current peaks with a 0.6 nm periodicty indicating the presence of charge ordering consisted of Fe dimers with different charge states. STM measurements using a magnetic Ni tip provide higher contrast of the charge ordering. The APBs can modify the charge ordering as ordered and disordered areas are observed on adjacent domains separated by an APB. These strongly indicate that APBs can induce inhomogeneous properties on the surface of Fe3O4(001) films. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Structures of incommensurate and commensurate composite crystals RbxMnO2 (x = 1.3711, 1.3636)ACTA CRYSTALLOGRAPHICA SECTION B, Issue 1 2010Jürgen Nuss Rb1.3711MnO2 (Rb11Mn8O16) has been synthesized via the azide/nitrate route from a stoichiometric mixture of the precursors Mn2O3, RbNO3 and RbN3. The structure of this extremely air- and moisture-sensitive compound can best be described in terms of an incommensurate composite structure, built up by a honeycomb-like framework of Rb ions, as one subsystem and by a second subsystem of chains, consisting of edge-sharing MnO4/2 tetrahedra. These two composite substructures interpenetrate in such a way that the manganate chain polyanions centre the channels of the Rb-honeycomb framework. Crystals transform by an aging process into Rb1.3636MnO2 (Rb15Mn11O22), which has a similar structure but a different commensurate modulation. Two reasons can be established for the origin of the modulations: the charge ordering of Mn2+/Mn3+ on one hand, and the incompatibility of the Mn,Mn and Rb,Rb separations on the other. [source] Isosymmetrical phase transition in ,-YbV4O8ACTA CRYSTALLOGRAPHICA SECTION B, Issue 6 2008Karen Friese The structure of YbV4O8 is related to the CaFe2O4 structure type. VO6 octahedra form a three-dimensional framework with tunnels in which the Yb3+ ions are incorporated. Two different polymorphs , and , are known and differ mainly in the arrangement of the Yb ions within the framework. We studied the structure and magnetic properties of ,-YbV4O8 as a function of temperature. At approximately 70,K ,-YbV4O8 undergoes a first-order isosymmetrical phase transition (P21/n,P21/n). While in the high-temperature , phase the three V3+ and one V4+ are disordered over the four symmetrically independent octahedral sites, in the low-temperature ,, phase complete charge ordering is observed. The transition is accompanied by a paramagnetic,paramagnetic anomaly in the magnetic susceptibility data which can be interpreted on the basis of spin-gap formation. The transition mechanism in the , polymorph is very similar to that observed earlier in the , polymorph at 185,K. [source] | ||||||||||