Corundum-to-spinel structural phase transformation in alumina

Adachi, Shogo; Ishimaru, Manabu; Sina, Younes; McHargue, C.J.; Sickafus, Kurt E.; Alves, E.

doi:10.1016/j.nimb.2015.06.005

Cited by 12 publications

(7 citation statements)

References 24 publications

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“…For example, the several different forms of aluminum oxide can be classified into hexagonal close‐packed (HCP) and FCC oxygen frameworks. [ 32 ] The most stable form ( α ‐Al 2 O 3 ) has a corundum structure with an HCP oxygen framework. On the other hand, the trivalent cobalt oxide Co 2 O 3 of the same corundum structure has been reported to be unstable; thus, neither the phase itself nor its formation has been studied as intensively as the spinel phase.…”

Section: Resultsmentioning

confidence: 99%

“…[33,34] The transformation of cobalt oxides was elucidated by comparison with the corundum 𝛼-Al 2 O 3 and spinel 𝛾-Al 2 O 3 transformation; the crystallographic orientational relationship in the case of alumina is consistent with our result. [32,35] Thus, in the case of cobalt oxide, the formation of Co 3 O 4 first occurs via cation migration without changes in oxygen stacking. Due to the high oxidation potential during overcharging, trivalent Co(III) 2 O 3 with a higher oxidation state (+3) becomes more favorable than the spinel phase (+2.67) even though they differ in oxygen stacking.…”

Section: Resultsmentioning

confidence: 99%

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Overcharge‐Induced Phase Heterogeneity and Resultant Twin‐Like Layer Deformation in Lithium Cobalt Oxide Cathode for Lithium‐Ion Batteries

Lee

Kim

et al. 2022

Advanced Science

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Overcharging is expected to be one of the solutions to overcome the current energy density limitation of lithium‐ion battery cathodes, which will support the rapid growth of the battery market. However, high‐voltage charging often poses a major safety threat including fatal incendiary incidents, limiting further application. Numerous researches are dedicated to the disadvantages of the overcharging process; nonetheless, the urgent demand for addressing failure mechanisms is still unfulfilled. Herein, it is revealed that overcharging induces phase heterogeneity into layered and cobalt oxide phases, and consequent “twin‐like deformation” in lithium cobalt oxide. The interplay between the uncommon cobalt(III) oxide and the deformation is investigated by revealing the atomistic formation mechanism. Most importantly, abnormal cracking is discovered in the vicinity of the cobalt oxide where structural instability induces substantial contraction. In addition, surface degradation is widely observed in the crack boundary inside the particle. As unintentional overcharging can occur due to local imbalance in state‐of‐charge in severe operating conditions such as fast charging, the issues on overcharging should be emphasized to large extent and this study provides fundamental knowledge of overcharge by elucidating the crack development mechanism of layered cathodes, which is expected to broaden the horizon into high voltage operation.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Overcharge‐Induced Phase Heterogeneity and Resultant Twin‐Like Layer Deformation in Lithium Cobalt Oxide Cathode for Lithium‐Ion Batteries

Lee

Kim

et al. 2022

Advanced Science

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“…At different temperatures and ambient pressure, the corundum is the most durable and dominant Al 2 O 3 phase. When aluminum hydroxide and aluminum oxy-hydroxide decompose, high-temperature oxidation of alumina-forming alloys occurs, and amorphous alumina recrystallizes, other metastable Al 2 O 3 polymorphs are generated before the most stable -Al 2 O 3 phase is reached [45].…”

Section: X-ray Diffraction Analysis (Xrd)mentioning

confidence: 99%

“…As the study of Tashvigh et al [46] shows, using a 5000 mg L −1 of salt, and TMP of 1 bar, under a steady-state condition, increases the thickness of the concentration polarization layer along the length of the membranes. phous alumina recrystallizes, other metastable Al2O3 polymorphs are generated before the most stable -Al2O3 phase is reached [45].…”

Section: Salinity-induced Changes For the Mullite Membranementioning

confidence: 99%

The Effect of Ceramic Membranes’ Structure on the Oil and Ions Removal in Pre-Treatment of the Desalter Unit Wastewater

et al. 2021

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Salts, organic materials, and hazardous materials can be found regularly in the effluent from a desalter unit of crude oil. These materials should be separated from the wastewater. Four kinds of inexpensive and innovative ceramic microfiltration membranes (mullite, mullite-alumina (MA 50%), mullite-alumina-zeolite (MAZ 20%), and mullite-zeolite (MZ 40%)) were synthesized in this research using locally available inexpensive raw materials such as kaolin clay, natural zeolite, and alpha-alumina powders. Analyses carried out on the membranes include XRD, SEM, void fraction, the average diameter of the pores, and the ability to withstand mechanical stress. Effluent from the desalter unit was synthesized in the laboratory using the salts most present in the desalter wastewater (NaCl, MgCl2, and CaCl2) and crude oil. This synthesized wastewater was treated with prepared ceramic membranes. It was discovered that different salt concentrations (0, 5000, 25,000, 50,000, 75,000, and 100,000 mg L−1) affected the permeate flux (PF), oil rejection, and ion rejection by the membrane. Results showed that in a lower concentration of salts (5000 and 25,000 mg L−1), PF of all types of ceramic membranes was increased significantly, while in the higher concentration, PF declined due to polarization concentration and high fouling effects. Oil and ion rejection was increased slightly by increasing salt dosage in wastewater due to higher ionic strength. Monovalent (Na+) and multivalent (Ca2+ and Mg2+) ion rejection was reported about 5 to 13%, and 23 to 40% respectively. Oil rejection varied from 96.2 to 99.2%.

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“…For example, the defect spinel structure of γ-alumina consists of a cubic close-packed oxygen lattice, in which 43% of the Al ions occupy octahedral sites (compare Figure in section ). ,, With rising temperature, the order within the aluminum as well as the oxygen sublattices increases, accompanied by dehydroxylation, loss of water, and densification, which leads finally to the thermodynamically stable and completely dehydrated α-form. A less ordered Al distribution is typical for all the early t-aluminas.…”

Section: Introduction To the Chemistry And The Use Of Aluminasmentioning

confidence: 99%

La-Doped Alumina, Lanthanum Aluminate, Lanthanum Hexaaluminate, and Related Compounds: A Review Covering Synthesis, Structure, and Practical Importance

Heveling

2023

Ind. Eng. Chem. Res.

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Advanced materials based on lanthanum–aluminum oxides are useful for many practical applications, not the least in catalysis, energy conversion and energy storage systems designed for a sustainable world economy. The three main La–Al–O (LAO) combinations of commercial interest are La-doped aluminas (LDA), lanthanum monoaluminate (LMA, a perovskite), and lanthanum hexaaluminate (LHA). Usually, the literature treats doped aluminas, perovskites, and hexaaluminates separately. The current review tries to identify common trends and features with respect to structure, synthesis, and applications of LAOs, which should lead to a more holistic understanding of their chemistry. This, in turn, should trigger innovative ideas with respect to new or improved applications. Apart from a variety of uses at low temperatures, the main advantages of LDA, LMA, LHA, and related compounds are their high-temperature stability and the extended applicability that comes with it.

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Corundum-to-spinel structural phase transformation in alumina

Cited by 12 publications

References 24 publications

Overcharge‐Induced Phase Heterogeneity and Resultant Twin‐Like Layer Deformation in Lithium Cobalt Oxide Cathode for Lithium‐Ion Batteries

Overcharge‐Induced Phase Heterogeneity and Resultant Twin‐Like Layer Deformation in Lithium Cobalt Oxide Cathode for Lithium‐Ion Batteries

The Effect of Ceramic Membranes’ Structure on the Oil and Ions Removal in Pre-Treatment of the Desalter Unit Wastewater

La-Doped Alumina, Lanthanum Aluminate, Lanthanum Hexaaluminate, and Related Compounds: A Review Covering Synthesis, Structure, and Practical Importance

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