Low temperature phase transitions and crystal structure of Na0.5CoO2

Abstract

The crystal structure of Na0.5CoO2, determined by powder neutron diffraction, is reported. The structure consists of layers of edge-shared CoO6 octahedra in a triangular lattice, with Na ions occupying ordered positions in the interleaving planes. The Na ions form one-dimensional zigzag chains. Two types of Co ions, which differ only subtly in their coordination by oxygen, are also found in chains. Specific heat measurements show that the transitions observed at 87 K and 53 K in the resistivity and magnetic susceptibility are accompanied by changes in entropy. Electron diffraction studies suggest that the 87K transition may have a structural component.

19 pages, 10 figures, submitted to Journal of Physics: Condensed Matter. Revised structural parameters on page 7

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• Charge-ordering, commensurability and metallicity in the phase diagram of layered Na(x)CoO(2)
• Crystal Structure of the Sodium Cobaltate Deuterate Superconductor NaxCoO2o4xD2O (x=1/3)
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Cited by in corpus (47)

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• Quasiparticle coherence and the nature of the metal-insulator phase transition in Na${}_x$CoO${}_2$
• Angle-resolved photoemission study of cobalt oxide superconductor NaxCoO2.yH2O : Observation of the Fermi surface
• Infrared spectroscopy of the charge ordering transition in Na${}_{0.5}$CoO${}_2$
• Structural transition in NaxCoO2 with x near 0.75 due to Na rearrangement
• Disproportionation Transition at Critical Interaction Strength: Na${}_{1/2}$CoO${}_2$
• Spin correlations and cobalt charge states: A new phase diagram of sodium cobaltates
• Structural Phase Transitions and Sodium Ordering in Na0.5CoO2: a Combined Electron Diffraction and Raman Spectroscopy Study
• Anomalous electronic Raman scattering in Na_xCoO_2 H_2O
• Competing orders in Na${}_x$CoO${}_2$ from strong correlations on a two-particle level
• Charge and spin order on the triangular lattice -- Na${}_x$CoO${}_2$ at $x=0.5$
• ^{59}Co NMR evidence for charge ordering below T_{CO}\sim 51 K in Na_{0.5}CoO_2
• Squaring the Triangle: Insulating Ground State of $N{a}_{0.5}Co{O}_2$
• Charge and Spin Ordering in Insulating Na${}_{0.5}$CoO${}_2$: Effects of Correlation and Symmetry
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• Geometrical, electronic and magnetic properties of Na${}_{0.5}$CoO${}_2$ from first principles
• Magnetic and Metal-Insulator Transitions in beta-Na0.5CoO2 and gamma-K0.5CoO2 -NMR and Neutron Diffraction Studies-
• Formation of charge and spin ordering in strongly correlated electron systems
• Strong correlations enhanced by charge-ordering in highly doped cobaltates
• Sodium Trimer Ordering on NaxCoO2 Surface
• Rearrangement of Sodium ordering and its effect on physical properties in $N{a}_{x}Co{O}_2$ system
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• Dimensional crossover and anomalous magnetoresistivity in single crystals $N{a}_{x}Co{O}_2$
• Localized versus itinerant magnetic moments in Na0.72CoO2
• Considerable non-local electronic correlations in strongly doped Na${}_x$CoO${}_2$
• Anisotropic Magnetoresistance in Charge-Ordering $N{a}_{0.34}(H_{3}O{)}_{0.15}Co{O}_2$:Strong Spin-Charge Coupling and Spin Ordering
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• Emergent charge ordering in near half doped Na${}_{0.46}$CoO${}_2$
• Pressure effects in the triangular layered cobaltites NaxCoO2
• Synthesis of sodium cobaltate Na${}_x$CoO${}_2$ single crystals with controlled Na ordering
• Chemical Differences between K and Na in Alkali Cobaltates
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• Superconductivity, charge ordering and structural properties of alpha and beta-NaxCoO2.y(H2O, D2O)
• Angular-dependent Magnetoresistance Oscillations in Na${}_{0.48}$CoO${}_2$ Single Crystal
• Charge ordering in charge-compensated $N{a}_{0.41}Co{O}_2$ by oxonium ions
• Electronic State of Na_xCoO_2 Based on the Two Dimensional Triangular Lattice d-p Model
• Phonon anomalies within the polar charge density wave phase of the structurally chiral superconductor Mo${}_3$Al${}_2$C
• Divacancy superstructures in thermoelectric calcium-doped sodium cobaltate
• Transition from a phase-segregated state to single-phase incommensurate sodium ordering in Na_xCoO_2 with x \approx 0.53
• Antiferromagnetic, Charge and Orbital Ordered States of Na0.5CoO2 Based on the Two-Dimensional Triangular Lattice d-p Model
• Temperature-driven sodium-ion dynamical-to-static crossover in the zig-zag ordered phase of Na${}_{0.5}$CoO${}_2$