Synthesis of sodium cobaltate NaxCoO2 single crystals with controlled Na ordering

Gilmutdinov, I. F.; Mukhamedshin, I. R.; Rullier‐Albenque, F.; Alloul, H.

doi:10.1016/j.jpcs.2018.05.022

Cited by 9 publications

(6 citation statements)

References 39 publications

(59 reference statements)

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“…Tanaka et al [134] showed that polycrystalline NaCo 2 O 4 is a good metal at temperatures up to 12 K, and demonstrates the Curie-Weiss magnetic susceptibility, instead of Pauli paramagnetism typical for metals. Gilmutdinov et al [135] synthesized single crystals of Na x CoO 2 with x ∼ 0.8 using the method of optical floating zones. Thorough electrochemical processing of the samples made it possible to control Na deintercalation and obtain single-crystal samples of stable ordered Na phases with x = 0.5-0.8.…”

Section: Layered Oxides Naxcoomentioning

confidence: 99%

Review of the thermoelectric properties of layered oxides and chalcogenides

Романенко¹,

Chebanova²,

Chen³

et al. 2021

J. Phys. D: Appl. Phys.

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The current state of investigation on thermoelectric properties of layered chalcogenides and oxides is considered. The relationship between the quasi-two-dimensionality of electronic transport properties and thermoelectric properties is confirmed. A decrease in the dimension of electron transport from three-dimensional to quasi-two-dimensional in materials with a layered structure increases the thermopower with a slight change in electrical conductivity. The bismuth tellurides, bismuth selenides and its alloys are currently one of the outstanding state of the art bulk thermoelectric materials with layered structure. Layered transition metal dichalcogenides MX$_2$ (M is a transition metal, X is a chalcogen) are efficient thermoelectric materials at higher temperatures (500-800 K). In these materials, an increase in thermoelectric properties associated with the two-dimensionalization of electron transport is also observed. Layered monochalcogenides MX (M = Sn, Pb, Ge; X = S, Se, Te) are also a promising class of thermoelectric materials. In SnSe single crystals, $ZT\sim$ 2.6 is obtained at 923 K due to the very low thermal conductivity along the $b$ axis (0.23 W/(m$\cdot$K) at 973 K). Layered chalcogenides CuCrX$_2$ (X - S, Se, Te) containing magnetic Cr atoms are effective thermoelectrics at higher temperatures (up to 800 K) due to the presence of phonon glass – electron crystal state led to a significant decrease in thermal conductivity at high temperatures. Magnetic atoms in CuCrX$_2$ compounds lead to the presence of magnetic phase transitions affecting their thermoelectric properties. Interest in oxide-based thermoelectric materials has significantly increased due to their stability in air and higher temperatures for maximum efficiency. The most promising thermoelectric oxide materials are Ca$_3$Co$_4$O$_9$, Na$_x$CoO$_2$, Bi$_2$Ca$_2$Co$_2$O$_x$, and CaCo$_2$O$_4$ have a layered structure and contain magnetic Co atoms leading to magnetic ordering and influence on thermoelectric properties. The presence of phase transitions affects the thermoelectric parameters of thermoelectrics and the thermoelectric figure of merit $ZT$.

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Section: Layered Oxides Naxcoomentioning

confidence: 99%

Review of the thermoelectric properties of layered oxides and chalcogenides

Романенко¹,

Chebanova²,

Chen³

et al. 2021

J. Phys. D: Appl. Phys.

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show abstract

“…If one compares the behavior of the Hall effect with that of the resistivity one can see on Fig. 6 that the onset of the low T decrease of the Hall effect coincides with the onset of a decrease of dρ/dT which indicates an inflexion point at about 30 K which has also been found quite reproducible (17). We might notice as well that the change of behavior of the Hall effect is concomitant with the large increase of the spin susceptibility detected by NMR without any onset of magnetic order down to T=0 (34).…”

Section: X=2/3 Kagome Like Phasementioning

confidence: 73%

“…Subsequent electrochemical treatment was used in order to decrease sodium content and to obtain crystals with homogeneous sodium distribution. Details of the sample preparation techniques and samples control have been described elsewhere (17).…”

Section: Appendix a : Samples And Measurement Techniquesmentioning

confidence: 99%

“…But in that respect the main difficulty has been so far the production of homogeneous and reproducible single crystals. We have done recently specific efforts to control as much as possible the quality of single crystal samples of ordered Na phases (17). This does allow us now to probe the bulk electronic properties by resistivity and Hall effect measurements.…”

Section: Introductionmentioning

confidence: 99%

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Hall effect evidence for an interplay between electronic correlations and Na order induced electronic bands topology in NaxCoO2

Gilmutdinov

Mukhamedshin

Alloul

2020

Phys. Rev. Materials

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The incidence of topology on the band structure and physical properties of layered compounds has been extensively studied in semimetals. How those evolve in presence of electronic correlations has been less investigated so far. In the sodium cobaltates NaxCoO2 considered here, unexpected magnetic properties associated with correlations on the Co sites have been disclosed about 15 years ago. Altogether it has also been found that various orderings of the Na atoms occur in between the CoO2 layers in the stable phases of these cobaltates. The distinct Na orders of these phases have been shown to induce specific Co charge disproportionation with large size unit cells in the CoO2 planes, linked with the diverse magnetic behaviors. This provides an original playground in the studies of interplays between topology and correlations in these layered materials. We present here transport measurements on a series of single crystals and demonstrate that we do synthetize pure phases with quite reproducible transport properties. We show that above room T those display a similar behavior whatever the Na content. On the contrary we evidence a great diversity in Hall effect low temperature dependences which underlines the specificities of the Fermi Surface reconstructions induced by the Na order. We study in some detail the difference between two metallic phases, one (x=0.77) antiferromagnetic below TN=22 K and the second (x=2/3) paramagnetic down to T=0. Both display a change of sign of Hall effect with decreasing T. We demonstrate that this can be attributed to quite distinct physical effects. For the x=0.77 phase the negative Hall effect has a non-linear field dependence and occurs in similar conditions as the anomalous Hall effect found in various magnetic metals. In the x=2/3 phase in which the Co sites are disproportionated in a kagome substructure, the singularities of the Hall effect have to be assigned with specificities of its Fermi surface. In both cases the detected Hall effect anomalies are certainly associated with the topology of their Co electronic bands.

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“…This excess of Na 2 CO 3 in the starting mixture compensates for the Na 2 O loss during the high temperature heat treatment. In another work, 43 NaCoO 2 was synthesized from the same reactants, but using a procedure in which the powder mixture was grinded manually in an agate mortar for 2 h, then loaded into an alumina crucible and subsequently sintered three times at 860 °C in air. In such synthesis procedure, intermediate grinding was performed in a moisture-free atmosphere inside a glove box to obtain an homogeneous composition.…”

Section: Resultsmentioning

confidence: 99%

Tracking sodium cobaltate formation pathways and its CO₂ capture dynamics in real time with synchrotron X-ray diffraction

Cova,

Blanco

2024

React. Chem. Eng.

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Synthesis of sodium cobaltate NaxCoO2 single crystals with controlled Na ordering

Cited by 9 publications

References 39 publications

Review of the thermoelectric properties of layered oxides and chalcogenides

Review of the thermoelectric properties of layered oxides and chalcogenides

Hall effect evidence for an interplay between electronic correlations and Na order induced electronic bands topology in NaxCoO2

Tracking sodium cobaltate formation pathways and its CO₂ capture dynamics in real time with synchrotron X-ray diffraction

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Synthesis of sodium cobaltate NaxCoO2 single crystals with controlled Na ordering

Cited by 9 publications

References 39 publications

Review of the thermoelectric properties of layered oxides and chalcogenides

Review of the thermoelectric properties of layered oxides and chalcogenides

Hall effect evidence for an interplay between electronic correlations and Na order induced electronic bands topology in NaxCoO2

Tracking sodium cobaltate formation pathways and its CO2 capture dynamics in real time with synchrotron X-ray diffraction

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Product

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Tracking sodium cobaltate formation pathways and its CO₂ capture dynamics in real time with synchrotron X-ray diffraction