Etude de l'ordre dans les solutions solides (CuO) χ (NiO) 1−χ

Zilber, R.; Bertaut, E.F.; Burlet, P.

doi:10.1016/0038-1098(70)90492-8

Cited by 9 publications

(5 citation statements)

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“…The stability to substitution of (Cu0.35Ni0.6~)O may be gauged by the appearance/disappearance of the tetragonal reflections and the diffuse scattering about the rocksalt (200) reflection. Previous work (18) has shown this phase assemblage is observed to Xcuo 0.70, where rocksalt solid solution and CuO (tenorite) coexist. In the ternary system substitution of Ni, Mg, or Cu, in (Cu0.~Ni0.65)O, results in a rapid decrease of the tetragonaI distortion.…”

Section: Resultsmentioning

confidence: 72%

“…Previous work (18) has shown this phase assemblage is observed to Xcuo 0.70, where rocksalt solid solution and CuO (tenorite) coexist. In the ternary system substitution of Ni, Mg, or Cu, in (Cu0.~Ni0.65)O, results in a rapid decrease of the tetragonaI distortion.…”

Section: Resultsmentioning

confidence: 88%

“…There have been structural studies on the nature of the ordered compounds occurring in the CuO-NiO (13,(15)(16)(17)(18) and CuO-MgO ( 14) system. Powder x-ray diffraction experiments on CuO-NiO compositions have suggested the existence of two ordered compounds, both showing tetragonal distortions from cubic symmetry.…”

Section: Catalytic Properties Oxide Solid Solutions Includingmentioning

confidence: 99%

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An X‐Ray Powder Diffraction Study of Phases in the System CuO ‐ NiO ‐ MgO at 1000°C

Davies

1982

J. Electrochem. Soc.

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Lattice parameter measurements using x-ray Guinier techniques found substantial negative deviations from Vegard's law in the NiO-MgO system at 600~ Negative deviations occur at 1000~ for samples containing small concentrations of CuO. Measurements of compositions in the CuO-NiO system allow prediction of the lattice constant of CuO having the rocksalt structure. The pressure at which CuO tenorite transforms to its rocksalt modification is estimated to be 335 kbar. An ordered compound, (Cu0.~sNio.65)O, shows a tetragonal distortion from cubic symmetry. Considerable diffuse scattering was observed in the powder diffraction pattern suggesting a variation in the local cation coordinations. This tetragonal distortion disappears rapidly in the ternary system. The ordered compound Cu2MgO~ is stable well into the ternary system, with strong evidence for Ni2+ substitution.Mixing properties in rocksalt oxide solid solutions are important in determining physical, surface, and catalytic properties. Oxide solid solutions, including NiO dissolved in MgO and (Ni,Mg)A1204 spinel phases, have been proposed for use in catalytic combustors both for improving combustion efficiency and for controlling oxides of nitrogen (NO=) (1-4).Until recently (5, 6) such solid solutions have been regarded as "simple" and easily characterized, both thermodynamically and structurally.Calorimetric studies of NiO-MgO have found sizable negative enthalpies of mixing throughout the solid solution series (5). When combined with previously determined activity-composition relations (7, 8), large negative excess entropies of mixing were also observed. This tendency toward order was supported by high resolution transmission electron microscopy studies of a sample (Ni0.4Mgo.6)O. Small domains, approximately 50-100A, were observed in several samples of this composition. The frequency of occurrence of the domains was found to increase with lower annealing temperatures. That the lower temperature samples show greater degrees of order was confirmed by further calorimetric studies (9).The ordering was explained by the covalency and directional character of the bonding of the Ni 2+ ion (5). A model was proposed in which the Ni2+ ion, when competing with spherically symmetrical ions of similar size (e.g., Mg 2+, Zn 2+) for the intermediate oxide anion, is able to allow a closer approach of the anions in one direction (5). This results in a distortion of the Ni 2+ polyhedra from a regular to a compressed octahedron. Such a mechanism leads to an ordered and stabilized solid solution.Cu 2+ and Ni 2+ have comparable octahedral ionic radii (10). Pure CuO crystallizes with the tenorite structure in which Cu 2+ is in square planar coordination. Partial solubility of CuO in MgO (11), CoO (12), and NiO (23) does occur. The solubility limits of the rocksalt solid solution are Xcuo ----0.21, 0.42, and 0.36, respectively, at temperatures near 1000~Intermediate ordered (CuxMu)Ox+~ compounds exist in all three systems (11-13). In CuO-MgO the intermediate compound, gfiggenite, ha...

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Section: Resultsmentioning

confidence: 72%

Section: Resultsmentioning

confidence: 88%

Section: Catalytic Properties Oxide Solid Solutions Includingmentioning

confidence: 99%

See 1 more Smart Citation

An X‐Ray Powder Diffraction Study of Phases in the System CuO ‐ NiO ‐ MgO at 1000°C

Davies

1982

J. Electrochem. Soc.

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“…18) Although the phase diagram of the Ni-Cu-O system has been reported by Zilber et al, it is an incomplete diagram. 19) In addition, Turky has synthesized NiO-CuO samples that can be used for catalytic applications. 20) However, the NiO-CuO system that they investigated was prepared under equilibrium conditions so that the amount of CuO was about 3 at.%.…”

Section: Introductionmentioning

confidence: 99%

Tetragonal Phase Change by Copper Solution in Nickel Oxide

Suzuki

Kamekawa

Nakayama

et al. 2010

Trans. Mat. Res. Soc. Japan

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Nickel copper oxide ((Ni 1-x Cu x )O) thin films, where the Cu content x was changed in the range from 0 to 1, were prepared by pulsed laser deposition. The copper content of the thin films was determined by energy-dispersive X-ray analysis with scanning electron microscopy. Transmission electron microscope observations of the thin film with x=0.52 revealed that the unit cell was distorted from cubic to tetragonal according to the Jahn-Teller effect by Cu 2+ ions dissolved in the NiO lattice. Key words: (Ni,Cu)O, Jahn-Teller effect, tetragonal, pulsed laser deposition, crystal structure INTRODUCTIONTransition metal oxides show various physical phenomena such as the metal-insulator transition, high temperature superconductivity, and enormous magnetic resistance. 1-7) The main origin of these properties is the d electrons of transition metal ions. Historically, the starting point of research on d electrons was a series of studies on Mott insulators including charge-transfer-type insulators. According to band theory, transition metal oxides should show metallic electrical conduction properties, but some of them are insulators because their d electrons are localized at each transition metal ion by a repulsive force between electrons. Among transition metal oxides, nickel oxide (NiO) is a charge-transfer-type insulator. 8) It has a NaCl-type (B1) structure and exhibits antiferromagnetism below the Néel temperature (T N = 523 K). These properties of NiO have been exploited in a variety of applications. It is known that NiO thin films are suitable for use in magnetoresistance sensors, electrochromic devices, transparent conducting films, and chemical sensors . [9][10][11] Various attempts have been made to add alloying elements into NiO. For example, it has been reported that in the Ni-Li-O system, hole carriers are introduced into NiO by substituting Li atoms for Ni since Li is ionized to Li + . 12) A Ni-Li-O phase has been used as a negative-temperature-coefficient thermistor. A Ni-Fe-O phase shows ferromagnetism caused by double-exchange interaction at room temperature, and is anticipated to be suitable for use in diluted magnetic semiconductor (DMS) applications. [13][14] The Ni-Nb-O system includes a phase being regarded as a promising catalyst used to substitute Nb 5+ for Ni 2+ . 15) In the Ni-Zn-O system, the addition of Zn into NiO has been observed to alter the electron structure and cause excitation from O(p) ->Ni(d) to O(p) -> Zn(s) as a result of Zn 2+ substitution. 16) Studies on NiO are expected to lead to new DMS and catalytic applications.In the present study, we attempted to add Cu 2+ ions into NiO. It is well known that Cu 2+ ions (d9) in an octahedral environment cause lattice distortion brought about by the Jahn-Teller effect. 17) The common

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“…18) Although the phase diagram of the Ni-Cu-O system has been reported by Zilber et al, it was an incomplete diagram. 19) In addition, Turky has mentioned that NiO-CuO samples were synthesized and can be used for catalyst applications. 20) However, the NiO-CuO system that they investigated was prepared under equilibrium conditions so that the amount of CuO was about 3 at.…”

Section: Introductionmentioning

confidence: 99%

(Ni,Cu)O Phase in Thin Films Prepared by Pulsed Laser Deposition

Kamekawa

Asami

Suzuki

et al. 2008

jjap

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Nickel copper oxide [(Ni 1Àx Cu x )O] thin films in which Cu content x was changed from 0 to 1 were prepared by pulsed laser deposition. The copper content of the thin films was determined by energy-dispersive X-ray analysis with scanning electron microscopy. Transmission electron microscope observation of the thin films with x ¼ 0:37 revealed that the thin films contained grains consisting of Ni, Cu, and O. Both interplanar distances and lattice constant increased with increasing copper content. The (Ni 1Àx Cu x )O phase with 0 < x < 0:27 has a B1 structure.

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Etude de l'ordre dans les solutions solides (CuO) χ (NiO) 1−χ

Cited by 9 publications

References 1 publication

An X‐Ray Powder Diffraction Study of Phases in the System CuO ‐ NiO ‐ MgO at 1000°C

An X‐Ray Powder Diffraction Study of Phases in the System CuO ‐ NiO ‐ MgO at 1000°C

Tetragonal Phase Change by Copper Solution in Nickel Oxide

(Ni,Cu)O Phase in Thin Films Prepared by Pulsed Laser Deposition

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