Crystal Structure of the Sodium Cobaltate Deuterate Superconductor NaxCoO2o4xD2O (x=1/3)

Abstract

Neutron and x-ray powder diffraction have been used to investigate the crystal structures of a sample of the newly-discovered superconducting sodium cobaltate deuterate compound with composition Na0.31(3)CoO2o1.25(2)D2O and its anhydrous parent compound Na0.61(1)CoO2. The deuterate superconducting compound is formed by coordinating four D2O molecules (two above and two below) to each Na ion in a way that gives Na-O distances nearly equal to those in the parent compound. One deuteron of the D2O molecule is hydrogen bonded to an oxygen atom in the CoO2 plane and the oxygen atom and the second deuteron of each D2O molecule lie approximately in a plane between the Na layer and the CoO2 layers. This coordination of Na by four D2O molecules leads to ordering of the Na ions and D2O molecules. The sample studied here, which has Tc=4.5 K, has a refined composition of Na0.31(3)CoO2o1.25(2)D2O, in agreement with the expected 1:4 ratio of Na to D2O. These results show that the optimal superconducting composition should be viewed as a specific hydrated compound, not a solid solution of Na and D2O (H2O) in NaxCoO2oyD2O. Studies of physical properties vs. Na or D2O composition should be viewed with caution until it is verified that the compound remains in the same phase over the composition range of the study.

22 pages, 8 figures

References in corpus (2)

• Spin entropy as the likely source of enhanced thermopower in $\rm\bf Na_xCo_2O_4
• Chemical Instability of the Cobalt Oxyhydrate Superconductor under Ambient Conditions

Cited by in corpus (42)

• Enhancement of superconducting transition temperature of FeSe by intercalation of a molecular spacer layer
• Electronic instabilities of kagome metals: saddle points and Landau theory
• Coupling between electronic and structural degrees of freedom in the triangular lattice conductor NaxCoO2
• Low temperature phase transitions and crystal structure of Na0.5CoO2
• Magnetism and structure of LixCoO2 and comparison to NaxCoO2
• Charge Disproportionation and Spin Ordering Tendencies in Na(x)CoO2
• Electronic phase diagram of the layered cobalt oxide system, LixCoO2 (0.0 <= x <= 1.0)
• The crystal growth and characterization of NaxCoO2 and NaxCoO2yH2O
• Charge ordering and magneto-polarons in Na${}_{0.82}$CoO${}_2$
• The Role of hybridization in NaxCoO2 and the Effect of Hydration
• Unconventional Charge Ordering in Na0.70CoO2 below 300 K
• Metamagnetic Transition in Na${}_{0.85}$CoO${}_2$ Single Crystals
• Revised superconducting phase diagram of hole doped Na${}_x$(H${}_3$O)${}_z$CoO${}_2\cdot y$H${}_2$O
• Magnetic susceptibility study of hydrated and non-hydrated NaxCoO2-yH2O single crystals
• Structural transition in NaxCoO2 with x near 0.75 due to Na rearrangement
• Infrared probe of the electronic structure and charge dynamics in Na${}_{0.7}$CoO${}_2$
• NQR and X-ray investigation of the structure of Na${}_{2/3}$CoO${}_2$ compound
• Structural Phase Transitions and Sodium Ordering in Na0.5CoO2: a Combined Electron Diffraction and Raman Spectroscopy Study
• Superconductivity and Cobalt Oxidation State in Metastable Na(x)CoO(2-delta)*yH2O (x ~ 1/3; y ~ 4x)
• Anomalous electronic Raman scattering in Na_xCoO_2 H_2O
• An ab-initio evaluation of the local effective interactions in the superconducting compound $Na\_0.35CoO\_2-1.3H\_2O$
• First principles lattice dynamics of NaCoO${}_2$
• Electronic States in Two-Dimensional Triangular Cobalt Oxides: Role of Electronic Correlation
• X-ray absorption spectroscopy on layered cobaltates Na_xCoO_2
• Stoichiometric oxygen content in NaxCoO2
• Itinerant in-plane magnetic fluctuations and many-body correlations in Na${}_x$CoO${}_2$
• 17-O NMR studies of a triangular-lattice superconductor Na{x}CoO{2}yH{2}O
• Unconventional Superconductivity Induced by Quantum Critical Fluctuations in Hydrate Cobaltate Na${}_x$(H${}_3$O)${}_z$CoO${}_x\cdot$ $y$H${}_2$O -- Relationship between Magnetic Fluctuations and the Superconductivity Revealed by a Co Nuclear Quadrupole Resonance --
• Deformation of Electronic Structures Due to CoO6 Distortion and Phase Diagrams of NaxCoO2.yH2O
• Effect of Na content and hydration on the excitation spectrum of the cobaltite Na_xCoO_2 yH_2O
• Study of intercalation and deintercalation of Na_xCoO_2 yH_2O single crystals
• Electronic Structure of Sodium Cobalt Oxide: Comparing Mono- and Bilayer-hydrate
• Water Content and Superconductivity in Na0.3CoO2*yH2O
• Effect of covalency and interactions on the trigonal splitting in NaxCoO2
• Hydration-induced anisotropic spin fluctuations in Na_{x}CoO_{2}\cdot1.3H_{2}O superconductor
• Electronic theory for itinerant in-plane magnetic fluctuations in Na${}_x$CoO${}_2$
• Thermal Expansion and Compressibility in Superconducting NaxCoO2o4xD2O (x?1/3): Evidence for Pressure-Induced Charge Redistribution
• Proton incorporations and superconductivity in a cobalt oxyhydrate
• Role of electronic correlations in the Fermi surface formation of Na${}_x$CoO${}_2$
• Numerical study of magnetic and pairing correlation in bilayer triangular lattice
• Influence of water intercalation on the electronic structure of the hydrated Na0.3CoO2.yH2O using a local spin density approximation
• Magnetic anomalies of hydrous cobaltate compound Na_x(H_3O)_zCoO_2 \cdot yH_2O detected by NMR and NQR measurements