Structure and properties of the CaFe2O4-type cobalt oxide CaCo2O4

Shizuya, Mitsuyuki; Isobe, Masaaki; Takayama‐Muromachi, E.

doi:10.1016/j.jssc.2007.07.008

Cited by 34 publications

(18 citation statements)

References 36 publications

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“…These two contributions were refined, resulting in the presence of oxygen atoms at two distances 1.92 and 2.13 Å and a first metal–metal distance at 3.08 Å, as shown in the inset text of Figure D. These results are consistent with values reported elsewhere for Co II ‐O OH bonds for octahedrally coordinated Co II , which are around 2.0 to 2.1 Å and Co III ‐O OH bounds for octahedrally coordinated Co III , which are close to 1.9 Å . By applying a simple bond‐valence parameters concept, an average oxidation state close to 2.5 is observed.…”

Section: Resultssupporting

confidence: 85%

High‐Performing Monometallic Cobalt Layered Double Hydroxide Supercapacitor with Defined Local Structure

Vialat

Mousty

Taviot-Guého

et al. 2014

Adv Funct Materials

149

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Through a topochemical oxidative reaction (TOR) under air, a β-Co(OH) 2 brucite type structure is converted into a monometallic Co II Co III -CO 3 layered double hydroxide (LDH). The structural and morphological characterizations are performed using powder X-ray diffraction, Fourier-transformed IR spectroscopy, and scanning and transmission electron microscopy. The local structure is scrutinized using an extended X-ray absorption fi ne structure, X-ray absorption near-edge structure, and pair distribution function analysis. The chemical composition of pristine material and its derivatives (electrochemically treated) are identifi ed by thermogravimetry analysis for the bulk and X-ray photoelectron spectroscopy for the surface. The electrochemical behavior is investigated on deposited thin fi lms in aqueous electrolyte (KOH) by cyclic voltammetry and electrochemical impedance spectroscopy, and their capacitive properties are further investigated by Galvanostatic cycling with potential limitation. The charge capacity is found to be as high as 1490 F g −1 for Co II Co III -CO 3 LDH at a current density of 0.5 A g −1 . The performances of these materials are described using Ragone plots, which fi nally allow us to propose them as promising supercapacitor materials. A surface-to-bulk comparison using the above characterization techniques gives insight into the cyclability and reversibility limits of this material.

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Section: Resultssupporting

confidence: 85%

High‐Performing Monometallic Cobalt Layered Double Hydroxide Supercapacitor with Defined Local Structure

Vialat

Mousty

Taviot-Guého

et al. 2014

Adv Funct Materials

149

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“…Specific-heat data of CaCo 2 O 4+d (main panel; C p /T versus T 2 plot). 4 The Sommerfeld constant c is 4.48(7) mJ/mol K 2 . The inset shows a schematic drawing of the energy band expected from the specific-heat data.…”

Section: Resultsmentioning

confidence: 99%

“…4 In this paper, we report the crystal structure and physical properties of CaCo 2 O 4+d , based on additional viewpoints following the original work in Ref. [4]. We found that the CaCo 2 O 4+d phase can exhibit a large thermoelectric power, even though it has a finite density of states at the Fermi level.…”

Section: Introductionmentioning

confidence: 87%

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Thermoelectric Properties of the One-Dimensional Cobalt Oxide CaCo2O4

Isobe

Arai

Takayama‐Muromachi

2009

Journal of Elec Materi

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In this work we studied the crystal structure and physical properties of the new one-dimensional cobalt oxide CaCo 2 O 4+d . The CaCo 2 O 4+d phase crystallizes as a calcium-ferrite-type structure, which consists of a corner-and edgeshared CoO 6 octahedron network including one-dimensional double chains. The specific-heat Sommerfeld constant c was found to be 4.48(7) mJ/mol K 2 . This result suggests that the CaCo 2 O 4+d phase has a finite density of states at the Fermi level. Metallic temperature dependence of the Seebeck coefficient S with a large thermoelectric power (S = 151 lV/K at 387 K) was observed. The origin of the large thermoelectric power may be attributed to the quasi onedimensional character of the energy band near the valence band maximum in CaCo 2 O 4+d .

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“…Several years ago, the so‐called calciumferrate(III) type (CaFe 2 O 4 ) was summarized (review article on AM 2 O 4 oxometallates30, p. 67). The compound CaCo 2 O 4 , described by Shizuya , Isobe , and Takayama ‐ Muromachi 31, belongs to this class of substances, too. Details on the crystal structure and on isotypic compounds can also be found there.…”

Section: G Mco2o4mentioning

confidence: 99%

On the Crystal Chemistry of Alkaline Earth‐ and Rare Earth‐Oxocobaltates

Müller‐Buschbaum

2013

Zeitschrift anorg allge chemie

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A review on the crystal chemistry of oxocobaltates of alkaline earth and rare earth metals is presented according to the formula of the compounds, based on increasing metal and oxygen content. The well‐known structures of perowskites and K2NiF4‐type compounds and their higher homologues have been ignored and cross‐referred to older publications. Cobalt shows mainly the oxidation states Co2+ and Co3+. In many cases it exhibits integer valences like Co2.28+, Co2.5+, Co2.54+, Co2.8+, Co3.5, and Co3.6+, referred in the ICSD database. The dominant coordination polyhedra are CoO4‐tetrahedra and CoO6‐oktahedra. In two cases a trigonal prismatic CoO6‐coordination is observed. Composition, crystal structure, and oxidation state of cobalt often depend on the preparation conditions. In contrast to the alkaline oxides, the alkaline earth and rare earth oxides used for preparations are less reactive. Therefore the necessary reaction temperatures are much higher. In these cases single crystals for x‐ray investigation were prepared by plasma‐burner and CO2‐LASER techniques.

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Structure and properties of the CaFe2O4-type cobalt oxide CaCo2O4

Cited by 34 publications

References 36 publications

High‐Performing Monometallic Cobalt Layered Double Hydroxide Supercapacitor with Defined Local Structure

High‐Performing Monometallic Cobalt Layered Double Hydroxide Supercapacitor with Defined Local Structure

Thermoelectric Properties of the One-Dimensional Cobalt Oxide CaCo2O4

On the Crystal Chemistry of Alkaline Earth‐ and Rare Earth‐Oxocobaltates

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