Electrical Properties of NiO

Morin, François

doi:10.1103/physrev.93.1199

Cited by 283 publications

(148 citation statements)

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“…2 In both phases, NiO behaves as an electric insulator, the conductivity of which increases as temperature rises 3 and remains insulating up to pressures on the order of 1 Mbar. [4][5][6] The clear nonconductivity observed in NiO is in contradiction to what can be expected from simple arguments regarding the partially filled 3d band.…”

Section: Introductionmentioning

confidence: 99%

Ab initioabsorption spectrum of NiO combining molecular dynamics with the embedded cluster approach in a discrete reaction field

et al. 2012

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We developed a procedure that combines three complementary computational methodologies to improve the theoretical description of the electronic structure of nickel oxide. The starting point is a Car-Parrinello molecular dynamics simulation to incorporate vibrorotational degrees of freedom into the material model. By means of complete active space self-consistent field second-order perturbation theory (CASPT2) calculations on embedded clusters extracted from the resulting trajectory, we describe localized spectroscopic phenomena on NiO with an efficient treatment of electron correlation. The inclusion of thermal motion into the theoretical description allows us to study electronic transitions that, otherwise, would be dipole forbidden in the ideal structure and results in a natural reproduction of the band broadening. Moreover, we improved the embedded cluster model by incorporating self-consistently at the complete active space self-consistent field (CASSCF) level a discrete (or direct) reaction field (DRF) in the cluster surroundings. The DRF approach offers an efficient treatment of electric response effects of the crystalline embedding to the electronic transitions localized in the cluster. We offer accurate theoretical estimates of the absorption spectrum and the density of states around the Fermi level of NiO, and a comprehensive explanation of the source of the broadening and the relaxation of the charge transfer states due to the adaptation of the environment.

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Section: Introductionmentioning

confidence: 99%

Ab initioabsorption spectrum of NiO combining molecular dynamics with the embedded cluster approach in a discrete reaction field

et al. 2012

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“…36 They lie close to peaks observed at 1.1 and 1.8 eV in oxidized Ni. 37 These spectra have been rationalized within semiempirical molecular-orbital theory for charge-transfer excitations in NiO·Ni 2 O 3 . We tentatively assign our peak at 2.1 eV to the higher of these transitions, but we were not able to resolve any features in our spectra at lower energies.…”

Section: Sample Characterizationmentioning

confidence: 99%

Coloration Mechanism in Proton-Intercalated Electrochromic Hydrated NiO[sub y] and Ni[sub 1−x]V[sub x]O[sub y] Thin Films

Avendaño¹,

Rensmo

Azens

et al. 2009

J. Electrochem. Soc.

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Electrochromic ͑EC͒ films of nickel oxide, with and without vanadium, were prepared by reactive dc magnetron sputtering. They were characterized by electrochemical and optical measurements and studied by X-ray photoelectron spectroscopy ͑PES͒ using synchrotron radiation. The films were analyzed under as-deposited conditions and after bleaching/coloration by insertion/ extraction of protons from a basic solution and ensuing charge stabilization. Optical measurements were consistent with a coloration process due to charge-transfer transitions from Ni 2+ to Ni 3+ states. The PES measurements showed a higher concentration of Ni 3+ in the colored films. Moreover, two peaks were present in the O 1s spectra of the bleached film and pointed to contributions of Ni͑OH͒ 2 and NiO. The changes in the O 1s spectra upon coloration treatment indicate the presence of Ni 2 O 3 in the colored film and necessitated an extension of the conventional model for the mechanism of EC coloration. The model involves not only proton extraction from nickel hydroxide to form nickel oxyhydroxide but also participation of NiO in the coloration process to form Electrochromic ͑EC͒ materials are able to change their optical properties reversibly and persistently upon charge insertion/ extraction under the application of an external voltage.1 Materials that color upon charge insertion/extraction are called cathodic/ anodic. These materials can be implemented in energy-saving and comfort-enhancing architectural "smart windows," and other application areas include mirrors with variable specular reflectance, nonemissive information displays, surfaces with variable thermal emittance, eyewear, etc.1-4 EC technology has been used for some niche applications for several years. However, the situation is now changing and electrochromism will reach wider applications. 5Thin films of Ni oxide possess anodic electrochromism, as discovered in the mid-1980s 6-9 and subsequently studied in a large number of investigations. [1][2][3][4] The visual appearance goes between transparent and brown upon extraction and insertion of charge. In EC devices incorporating cathodically coloring W oxide films, the brown color of Ni oxide is complementary to the blue color of W oxide, both together yielding a neutral ͑gray͒ color in transmittance for dark films. Ni oxide films produced for EC applications exhibit a cubic polycrystalline structure 1,9-14 and a density between 3 and 6.5 g/cm 3 depending on deposition conditions. 1,14,15 The low density is indicative of porosity. 10,14,16 The grain size depends strongly on film deposition conditions and can range from 3 to 300 nm. 9,10,12,14,15,17 The porosity and small grain size, leading to a large surface-to-bulk ratio, increase the EC activity of the films, 12,18,19 and the reaction that produces the color takes place in the outermost parts of the grains. 12Several varieties of reactively sputter-deposited EC hydrated nickel-based oxide thin films have been reported. [1][2][3][4]20 Optimized Ni 1−x V x O y films made by sputter...

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“…Table 4 is 220 + 25 kJ mol-', i.e., roughly twice that of the dry decomposition reaction. Table 4 also shows that the presence of 0, causes a marked acceleration of the hydrothermal decomposition, the product being black NiO,,, rather than the leaf green, stoichiometric (42)(43)(44) NiO that was obtained in the reactions under nitrogen. Green NiO prepared hydrothermally was not visibly affected by subsequent exposure to air, whereas green NiO prepared by decomposition of dry Ni(OH), in vacuo turned black immediately on contact with air; this difference may be attributed to the much larger specific surface of the small, porous (30) NiO particles formed by the vacuum decomposition relative to the small ( 1 0 .…”

Section: Resultsmentioning

confidence: 99%

Hydrothermal reaction kinetics. The decomposition of nickel(II) hydroxide

Swaddle¹,

Wong²

1978

Can. J. Chem.

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The fractional extent α of decomposition of ripened Ni(OH)2 into green NiO in alkaline hydrothermal conditions under nitrogen is given by the rate law α1/3 = kc[OH−]t, where kc = 2.4 × 10−5 kg mol−1 s−1 at 561 K. The Arrhenius activation energy is 220 + 25 kJ mol−1. The reaction is accelerated moderately by O2 (giving black NiO1+δ) and strongly by added NiO. A reaction mechanism involving dissolution of Ni(OH)2 as Ni(OH)3− (aq) and rate-determining, surface-controlled reprecipitation of this as NiO is proposed.

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Electrical Properties of NiO

Cited by 283 publications

References 3 publications

Ab initioabsorption spectrum of NiO combining molecular dynamics with the embedded cluster approach in a discrete reaction field

Ab initioabsorption spectrum of NiO combining molecular dynamics with the embedded cluster approach in a discrete reaction field

Coloration Mechanism in Proton-Intercalated Electrochromic Hydrated NiO[sub y] and Ni[sub 1−x]V[sub x]O[sub y] Thin Films

Hydrothermal reaction kinetics. The decomposition of nickel(II) hydroxide

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