Internal Reactions in Oxide Solid Solutions

Ostyn, K.M.; Carter, C.B.; Koehne, M.; Falke, H.E.; Schmalzried, H.

doi:10.1111/j.1151-2916.1984.tb19682.x

Cited by 56 publications

(20 citation statements)

References 7 publications

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“…We infer that the CO 2 splitting reaction over NiFe 2 O 4 /MgO begins with a transition from wüstite to spinel at the spinel/wüstite interphase boundary of the surface. The transition from wüstite to spinel is limited by the diffusion of metal ions because the diffusion coefficients of cations are higher than the diffusion coefficient of oxygen ion in the solid solution wüstite . When the external reaction ends, the CO generation reactions of NiFe 2 O 4 /SiO 2 and NiFe 2 O 4 /ZrO 2 still follow the F1 mechanism.…”

Section: Discussionmentioning

confidence: 99%

Differences in the Nature of Reaction Process for Thermochemical CO₂ Splitting over NiFe₂O₄‐Based Materials

Huang

Kong

et al. 2019

Energy Tech

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Perspectives concerning the two‐step thermochemical CO2 splitting via NiFe2O4‐based materials are given for CO production. The thermochemical reactivity of these materials is investigated, and the nature of reaction process is discussed. NiFe2O4/MgO exhibits universally better performance, giving 3–10 times higher CO production than that of two other materials, NiFe2O4/SiO2 and NiFe2O4/ZrO2. A comprehensive analysis indicates that the spinel ferrites in NiFe2O4/MgO can dissolve in and exsolve out of the wüstite matrix in synchronization with the temperature swing, leading to the self‐regeneration of spinel ferrites, which alleviates the sintering of NiFe2O4/MgO. Meanwhile, a similar dynamic transition between spinel and wüstite occurs under the periodic variation between reductive and oxidative atmospheres, associated with the internal reaction that promotes the interior iron diffusion, which plays a critical role in enhancing the reactivity of NiFe2O4/MgO.

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Section: Discussionmentioning

confidence: 99%

Differences in the Nature of Reaction Process for Thermochemical CO₂ Splitting over NiFe₂O₄‐Based Materials

Huang

Kong

et al. 2019

Energy Tech

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“…The critical size for NiFe 2 O 4 spinel nucleation was estimated to be 4.3 nm and the embryos were also found to be bounded by <1 1 1> planes with an octahedral morphology for a minimum energy. The grown spinel plate however has {1 0 0} habit plane as for NiFe 2 O 4 in NiO [15] …”

Section: Formation Of Spinel Embryo With Stable Habit Planementioning

confidence: 96%

“…We focused on: (1) the precipitation of secondary spinel at grain boundaries when the composite was slowly cooled in the furnace; (2) thermalmismatch induced {1 1 0}-specific cleaving and spontaneous healing precipitation to form parallel-epitaxial platy spinel within the grains when the composite was rapid cooled in air; and (3) the intrinsic shape of the spinel nucleus in a matrix of rock salt-type proto-oxide, as a comparison with previously reported case of NiFe 2 O 4 precipitation in NiO [15,16]. www.elsevier.com/locate/ceramint…”

Section: Introductionmentioning

confidence: 97%

Spinel precipitation in Sn4+-doped Co1−xO polycrystals with dispersed Co2+xSn1−xO4 particles

Pan

Shen

2010

Ceramics International

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“…For example, under certain conditions, partial or selective reactions with multicomponent compounds or solid solutions comprising at least one thermodynamically noble constituent can be variously termed in situ reactions, internal displacement reactions, or internal reduction reactions by analogy to nomenclature established in alloy oxidation literature. [39][40][41][42][43] Examples of solid-state displacement reactions in selected oxide and carbide systems are provided in Table 1.…”

Section: Introductionmentioning

confidence: 99%

Gas‐solid displacement reactions in the Ti–W–C system

Dempsey

Lipke

2019

J Am Ceram Soc

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Displacement reactions between binary and ternary ceramics in the Ti–W–C system and reactive gaseous atmospheres are investigated in this work. Specifically, WC and 50:50 wt% TiC:WC solid solution powders were exposed to flowing hydrogen gas, or equilibrated against an excess of titanium in the presence of iodine, to form metallic tungsten and TiC solid products. In the case of pure WC reacting with hydrogen, transformation to metallic tungsten occurred as a result of removal of chemically bound carbon as gaseous hydrocarbons. In the case of pure WC reacting with titanium iodide vapors, transformation was accompanied by the appearance of TiC as a solid product formed at the gas‐solid interface. In the case of 50:50 wt% TiC:WC solid solution powders, hydrogen was generally found to be an ineffective displacing reagent, whereas reaction with titanium iodide vapors was observed to proceed virtually to completion, resulting in a two phase product mixture comprising metallic tungsten and TiC. For the latter case, a variety of microstructures could be observed within a given batch, including tungsten platelets and/or lamellae in a TiC matrix, or coarse tungsten grains interspersed with TiC grains. These morphological variations are speculated to arise from compositional variation in the starting material and the occurrence of local rapid coarsening along fast diffusion pathways within reacting agglomerates and polycrystalline primary particles. The observed reaction products and relative efficacy of gaseous reagents to promote displacement reactions in the Ti–W–C system are rationalized on the basis of thermodynamic predictions. The reaction between 50:50 wt% TiC:WC solid solution powders and titanium iodide vapors constitutes the first known report of an internal displacement reaction proceeding via gaseous intermediates in a nonoxide ceramic system.

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Internal Reactions in Oxide Solid Solutions

Cited by 56 publications

References 7 publications

Differences in the Nature of Reaction Process for Thermochemical CO₂ Splitting over NiFe₂O₄‐Based Materials

Differences in the Nature of Reaction Process for Thermochemical CO₂ Splitting over NiFe₂O₄‐Based Materials

Spinel precipitation in Sn4+-doped Co1−xO polycrystals with dispersed Co2+xSn1−xO4 particles

Gas‐solid displacement reactions in the Ti–W–C system

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Internal Reactions in Oxide Solid Solutions

Cited by 56 publications

References 7 publications

Differences in the Nature of Reaction Process for Thermochemical CO2 Splitting over NiFe2O4‐Based Materials

Differences in the Nature of Reaction Process for Thermochemical CO2 Splitting over NiFe2O4‐Based Materials

Spinel precipitation in Sn4+-doped Co1−xO polycrystals with dispersed Co2+xSn1−xO4 particles

Gas‐solid displacement reactions in the Ti–W–C system

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Product

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Differences in the Nature of Reaction Process for Thermochemical CO₂ Splitting over NiFe₂O₄‐Based Materials

Differences in the Nature of Reaction Process for Thermochemical CO₂ Splitting over NiFe₂O₄‐Based Materials