Melting of the Na layers in solid Na0.8CoO2

Abstract

Data of 23Na NMR spectra- and relaxation measurements are interpreted as suggesting that, upon increasing temperature the Na layers in Na0.8CoO2 adopt a 2D liquid state at T=291 K. The corresponding first order phase transition is preceded by a rapidly increasing mobility and diffusion of Na ions above 200K. Above 291 K the 23Na NMR response is similar to that previously observed in superionic conductors with planar Na layers.

4 pages, 4 figures

References in corpus (10)

• Patterning of sodium ions and the control of electrons in sodium cobaltate
• Coupling between electronic and structural degrees of freedom in the triangular lattice conductor NaxCoO2
• Theory of Sodium Ordering in NaxCoO2
• Unconventional Charge Ordering in Na0.70CoO2 below 300 K
• Non-magnetic insulator state in Na1CoO2 and phase separation of Na vacancies
• Electronic texture of the thermoelectric oxide Na0.75CoO2
• Direct link between low temperature magnetism and high temperature sodium order in NaxCoO2
• Na atomic order, Co charge disproportionation and magnetism in Na${}_x$CoO${}_2$ for large Na contents
• Localized versus itinerant magnetic moments in Na0.72CoO2
• Magnetic Phase Transition at 88 K in Na0.5CoO2 revealed by 23Na-NMR investigations

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• Crystal-to-stripe reordering of sodium ions in NaxCoO2 (x>=0.75)
• Theoretical analysis of oxygen vacancies in layered sodium cobaltate Na_xCoO_{2-δ}
• Restoration of long range order of Na ions in $N{a}_{x}Co{O}_2$ at high temperatures by sodium site doping
• Novel electronic states realized by the interplay between Li diffusion and Co${}^{3+}$$/$Co${}^{4+}$ charge ordering in Li${}_{\mathrm{x}}$CoO${}_2$
• Na-ion dynamics in Quasi-1D compound NaV2O4
• Metal-nonmetal transition in LixCoO2 thin film and thermopower enhancement at high Li concentration
• The Duel of Magnetic Interactions & Structural Instabilities: Itinerant Frustration in the Triangular Lattice Compound LiCrSe${}_2$
• Na Site Doping a Pathway for Enhanced Thermoelectric Performance in $N{a}_{1-x}Co{O}_2$; The Case of Gd and Yb Dopants
• ${}^{139}$La and ${}^{63}$Cu NMR investigation of charge order in La${}_2$CuO${}_{4+y}$ ($T_c=42$K)
• Transition from a phase-segregated state to single-phase incommensurate sodium ordering in Na_xCoO_2 with x \approx 0.53
• Sodium ion ordering of Na0.77CoO2 under competing multi-vacancy cluster, superlattice and domain formation
• Local Structure of Functional Solids
• Temperature-driven sodium-ion dynamical-to-static crossover in the zig-zag ordered phase of Na${}_{0.5}$CoO${}_2$