Single-crystal growth, crystal and electronic structure of NaCoO2

Macroscopic magnetization, muon spin rotation (µSR), and NMR measurements were carried out to study magnetism in the Na1CoO2 cobaltate. Using superconducting quantum interference device measurements, Na1CoO2 is shown to have a bulk magnetic susceptibility much lower and flatter than that of NaxCoO2 with x=0.7-0.9. In fact, µSR yields a signal of mostly nonmagnetic origin, which is attributed to the x=1 phase. The intrinsic cobalt spin susceptibility corresponding to this x=1 phase is measured using 23 Na NMR. It is indeed found to be almost zero, in agreement with a low-spin 3+ charge state of all cobalt atoms. This single state of Co ions in CoO2 planes is confirmed by 59 Co NMR, whose determination of cobalt shift and quadrupolar parameters allows us to give a reference value of the Co 3+ orbital shift in cobaltates.

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“…12 We used Na 1 CoO 2 powder prepared by solid-state reaction of a stoichiometric mix of Co 3 O 4 and Na 2 O 2 . Synthesis took place at 700…”

Section: Crystallographic Structurementioning

confidence: 99%

Evidence of a single nonmagneticCo3+state in theNa1CoO2cobaltate

et al. 2005

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“…[8] Such polymorphs are represented by a combination of the geometrical shape of the site for the alkali metal ions (P: trigonal prism, O: octahedron, and T: tetrahedron) and the number of MO 2 sheets. The first superconducting cobalt oxide (hereafter referred to as the P2-phase superconductor), as well as its parent compound, c-Na In the present study, we started with a-NaCoO 2 having an O3 structure (space group: R3m), [6,9] where the oxygen stack- . However, the O3 structure is never transformed into a P2 phase by soft-chemical processes at ambient temperature, because the thermal energy is not high enough to rearrange the oxygen atoms around the Co atom.…”

mentioning

confidence: 99%

A New Superconducting Phase of Sodium Cobalt Oxide

et al. 2004

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“…Single crystals of Na 0.75 CoO 2 have been grown by flux method [6][7][8] and floating zone (FZ) method [9][10][11][12][13][14]. Sales et al [9] reported the first FZ growth of Na 0.75 CoO 2 .…”

Section: Introductionmentioning

confidence: 99%

Effect of rotation of feed and seed rods on the quality of Na0.75CoO2 single crystal grown by traveling solvent floating zone method

Sekar

Paulraj

Kanchana

et al. 2011

Materials Research Bulletin

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High purity Na 0.75 CoO 2 single crystals have been grown by floating zone method. We found the rotation of feed and seed rods play a crucial role in growing high quality single crystal.Systematic investigations suggest the occurrence of a phase separation at microscopic level, such as the separation into Na-rich and Na-poor domains during the growth, and formation of impurity phase(s) depending on growth conditions. Na x CoO 2 (x = 0.30, 0.60) crystals have been prepared by sodium deintercalation from Na 0.75 CoO 2 . Powder X-ray and energy dispersive X-ray analyses have confirmed the phase purity and homogeneity of the samples. Magnetic susceptibility measurements of x = 0.60 and 0.75 crystals indicate a bulk phase transition at 22 K and an anomaly around 339 K and 334 K respectively which are attributed to structural transition. In addition some unique features related to Na 0.60 CoO 2 were observed.

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Single-crystal growth, crystal and electronic structure of NaCoO2

Cited by 75 publications

References 17 publications

Evidence of a single nonmagneticCo3+state in theNa1CoO2cobaltate

Evidence of a single nonmagneticCo3+state in theNa1CoO2cobaltate

A New Superconducting Phase of Sodium Cobalt Oxide

Effect of rotation of feed and seed rods on the quality of Na0.75CoO2 single crystal grown by traveling solvent floating zone method

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