Growth and electrical properties of pure and Ni-doped Co3O4 single crystals

Tareen, J. A. K.; Małecki, Andrzej; Doumerc, Jean‐Pierre; Launay, Jean-Claude; Dordor, P.; Pouchard, Michel; Hagenmuller, Paul

doi:10.1016/0025-5408(84)90212-5

Cited by 52 publications

(18 citation statements)

References 11 publications

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“…Our conclusion regarding the cationic occupation is in agreement with early reports indicating that nickel occupies the octahedral sites while cobalt fills the remaining octahedral sites and, subsequently, the tetrahedral sites. [21] In the tetragonal phase, obtained with high nickel doping, the unit-cell volume was not sensitive to a further increase in nickel doping concentration, which might be attributed to cations disorder, characterized by the existence of both cations in multiple valences and in multiple sites. The crystallite size decreased with increased nickel doping concentrations, which can be associated with an increased microstrain.…”

Section: Resultsmentioning

confidence: 95%

Preparation of Doped Spinel Cobalt Oxide Thin Films and Evaluation of their Thermal Stability

Bahlawane

Premkumar

Feldmann

et al. 2007

Chemical Vapor Deposition

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Spinel cobalt oxide doped with nickel and zinc are deposited using a CVD reactor equipped with a pulsed spray evaporation system. This process allows easy control of the film composition through the adjustment of the composition of the liquid feedstock; a linear dependence is observed in both cases. Doped spinels with atomic ratios of doping-metal to Co ranging from 0 to 0.5 are deposited and subjected to various surface characterization methods. Zinc as a doping metal, which nonselectively occupies the octahedral and the tetrahedral sites, preserves the cubic spinel structure; in contrast, nickel, which preferably occupies the octahedral sites, preserves the cubic structure only up to Ni/Co = 0.14 and then induces a tetragonal distortion. This disordered structure allows more polarons, and therefore presents a conductivity which increases substantially with the concentration of nickel in the deposited films. The thermal stability of cobalt oxide is maintained in the case of nickel doping as long as the cubic structure is preserved, and then decreases continuously with the concentration of nickel doping once the tetragonal deformation is induced. An upper thermal stability limit as low as 350°C is observed for films with Ni/Co = 0.33. In contrast, zinc steadily improved the thermal stability with increased doping concentration, and reaches ∼850°C, which is 200°C higher than that of pure cobalt oxide.

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Section: Resultsmentioning

confidence: 95%

Preparation of Doped Spinel Cobalt Oxide Thin Films and Evaluation of their Thermal Stability

Bahlawane

Premkumar

Feldmann

et al. 2007

Chemical Vapor Deposition

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“…In addition, Windisch et al reported that inserted Ni 2+ ions into octahedral sites would cause structural distortion, as evidenced by the shift of Raman band to lower frequencies [46]. Note that Co3O4 has a normal spinel structure of AB2O4 type which consists of Co 2+ ions and Co 3+ ions occupying the tetrahedral sites and the octahedral sites, respectively [47][48][49]. Thus, EXAFS results evidently verify that most Ni 2+ ions are primarily inserted into the octahedral sites in Co3O4 spinel structure, while the portion of Co 3+ ions occupying the octahedral sites decreases.…”

Section: Exafs Resultsmentioning

confidence: 96%

Effect of Co/Ni ratios in cobalt nickel mixed oxide catalysts on methane combustion

Lim

Cho

Yang

et al. 2015

Applied Catalysis A: General

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2Graphical abstract Highlights 1. Co-Ni mixed oxide having the ratios of Co to Ni of (50:50) exhibits the highest activity among the known transition metal oxide catalysts.2. Co-Ni mixed oxides having the ratios of Co to Ni of (50:50) show the highest activity for methane combustion.3. Distorted NiCo2O4 spinel structure plays a key role as the active sites for methane combustion.3 Abstract A series of cobalt nickel mixed oxide catalysts with the varying ratios of Co to Ni, prepared by co-precipitation method, were applied to methane combustion. Among the various ratios, cobalt nickel mixed oxides having the ratios of Co to Ni of (50:50) and (67:33) demonstrate the highest activity for methane combustion. Structural analysis obtained from X-Ray Diffraction (XRD) and Extended X-ray Absorption Fine Structure (EXAFS) evidently demonstrates that CoNi (50:50) and (67:33) samples consist of NiCo2O4 and NiO phase and, more importantly, NiCo2O4 spinel structure is largely distorted, which is attributed to the insertion of Ni 2+ ions into octahedral sites in Co3O4 spinel structure. Such structural disorder results in the enhanced portion of surface oxygen species, thus leading to the improved reducibility of the catalysts in the low temperature region as evidenced by temperature programmed reduction by hydrogen (H2 TPR) and X-ray Photoelectron Spectroscopy (XPS) O 1s results. They prove that structural disorder in cobalt nickel mixed oxides enhances the catalytic performance for methane combustion. Thus, it is concluded that a strong relationship between structural property and activity in cobalt nickel mixed oxide for methane combustion exists and, more importantly, distorted NiCo2O4 spinel structure is found to be an active site for methane combustion.

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“…A variation in the conductivity is observed in this material with a change in the Ni:Co ratio and at Ni:Co = 1:2, the highest conductivity in these films was observed around 16.0 S cm −1 . It has also been proposed by various authors that Ni +3 ions located on octahedral sites within the spinel lattice enhance the conductivity of the film [102]. Figure 12.5 shows the variation of resistivity of Ni−Co−O thin films with composition x (=Co/{Co + Ni}).…”

Section: P-tco With Spinel Structurementioning

confidence: 95%

Reactive SputteredWide-Bandgap p-Type Semiconducting Spinel AB2O4 and Delafossite ABO2 Thin Films for “Transparent Electronics”

Banerjee¹,

Chattopadhyay

2008

Reactive Sputter Deposition

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Reactive sputtering is one of the most widely used techniques for preparing compound thin films (such as oxides, nitrides, carbides, etc.) by sputtering metal targets in an active gas atmosphere (Ar + O 2 /N 2 /CH 4 , etc.) [1][2][3][4]. In this chapter, we have discussed, in details, the formation of spinel and delafossite materials of the form AB 2 O 4 and ABO 2 (A and B may be monovalent, divalent, trivalent, or tetravalent cations, depending on the crystal structure, described later) by reactive sputtering technique. Specially, wide bandgap, ptype semiconducting, and transparent oxide materials with delafossite and spinel structure, having interesting applications in "Transparent Electronics," have been discussed in details. In Sects. 12.2-12.5, a detailed review on the structural, optical, and electrical properties of these p-type transparent conducting oxides (p-TCOs), deposited by reactive sputtering technique, has been presented and the origin of p-type conductivity of these materials has been discussed with considerable attention. Most of the results presented in these sections are reported by various authors working on this field. In Sect. 12.6, synthesis and electro-optical characterization of one of the very important delafossite, p-type semiconducting, and wide-bandgap material, such as CuAlO 2 , produced by our group via reactive sputtering technique, have been discussed in details. Detailed discussions on spinel-and delafossitestructured material can be found in various literatures [5][6][7][8][9][10][11][12][13][14]. Also, detailed reviews on the p-TCO materials have been published by us and others [15][16][17], which cover the syntheses and properties of a range of p-TCO materials reported so far.

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Growth and electrical properties of pure and Ni-doped Co3O4 single crystals

Cited by 52 publications

References 11 publications

Preparation of Doped Spinel Cobalt Oxide Thin Films and Evaluation of their Thermal Stability

Preparation of Doped Spinel Cobalt Oxide Thin Films and Evaluation of their Thermal Stability

Effect of Co/Ni ratios in cobalt nickel mixed oxide catalysts on methane combustion

Reactive SputteredWide-Bandgap p-Type Semiconducting Spinel AB2O4 and Delafossite ABO2 Thin Films for “Transparent Electronics”

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