X-ray and neutron total scattering analysis of Hy·(Bi0.2Ca0.55Sr0.25)(Ag0.25Na0.75)Nb3O10·xH2O perovskite nanosheet booklets with stacking disorder

Metz, Peter; Koch, R. J.; Cladek, Bernadette R.; Page, Katharine; Neuefeind, Jöerg C.; Misture, Scott T.

doi:10.1017/s0885715616000129

Cited by 3 publications

(2 citation statements)

References 34 publications

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“…This complex stacking disorder was modeled by a large supercell approach in which one hundred Sr 2 MnO 2 Ch 2 layers were allowed to move individually relative to one another during the refinement (Figure 12b). This free-parameter approach similar to the one reported by Metz et al 106 has successfully identified the most frequent stacking vectors (S x , S y ) in their disordered stacking (Figure 12d). Such characterizations of stacking vectors provide ideas about possible local structures of disordered low-dimensional polychalcogenides.…”

Section: Characterizationssupporting

confidence: 54%

Anionic Redox Topochemistry for Materials Design: Chalcogenides and Beyond

Sasaki,

Clarke,

Jobic

et al. 2023

ACS Org. Inorg. Au

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Topochemistry refers to a generic category of solidstate reactions in which precursors and products display strong filiation in their crystal structures. Various low-dimensional materials are subject to this stepwise structure transformation by accommodating guest atoms or molecules in between their 2D slabs or 1D chains loosely bound by van der Waals (vdW) interactions. Those processes are driven by redox reactions between guests and the host framework, where transition metal cations have been widely exploited as the redox center. Topochemistry coupled with this cationic redox not only enables technological applications such as Li-ion secondary batteries but also serves as a powerful tool for structural or electronic fine-tuning of layered transition metal compounds. Over recent years, we have been pursuing materials design beyond this cationic redox topochemistry that was mostly limited to 2D or 1D vdW systems. For this, we proposed new topochemical reactions of non-vdW compounds built of 2D arrays of anionic chalcogen dimers alternating with redox-inert host cationic layers. These chalcogen dimers were found to undergo redox reaction with external metal elements, triggering either (1) insertion of these metals to construct 2D metal chalcogenides or (2) deintercalation of the constituent chalcogen anions. As a whole, this topochemistry works like a "zipper", where reductive cleavage of anionic chalcogen−chalcogen bonds opens up spaces in non-vdW materials, allowing the formation of novel layered structures. This Perspective briefly summarizes seminal examples of unique structure transformations achieved by anionic redox topochemistry as well as challenges on their syntheses and characterizations.

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Section: Characterizationssupporting

confidence: 54%

Anionic Redox Topochemistry for Materials Design: Chalcogenides and Beyond

Sasaki,

Clarke,

Jobic

et al. 2023

ACS Org. Inorg. Au

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“…The DIFFaX routine (Treacy et al, 1991) enables the simulation of diffraction patterns as a function of the degree and type of faulting. Supercell approaches with a limited number of layers that are shifted freely (Wang et al, 2011;Metz et al, 2016) or constrained Mangelsen et al, 2019) perpendicular to the stacking direction have been used to approximate the microstructures of stacking-faulted samples and allow a refinement of the degree of disorder to a certain extent. the microstructure, of stacking-faulted brucite-type Mg(OH) 2 (Radha et al, 2003) and Ni(OH) 2 (Ramesh et al, 2003;Ramesh & Kamath, 2008) can be extracted.…”

Section: Introductionmentioning

confidence: 99%

A routine for the determination of the microstructure of stacking-faulted nickel cobalt aluminium hydroxide precursors for lithium nickel cobalt aluminium oxide battery materials

Bette

Hinrichsen

Pfister³

et al. 2020

J Appl Cryst

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The microstructures of six stacking-faulted industrially produced cobalt- and aluminium-bearing nickel layered double hydroxide (LDH) samples that are used as precursors for Li(Ni1−x−yCo x Al y )O2 battery materials were investigated. Shifts from the brucite-type (AγB)□(AγB)□ stacking pattern to the CdCl2-type (AγB)□(CβA)□(BαC)□ and the CrOOH-type (BγA)□(AβC)□(CαB)□ stacking order, as well as random intercalation of water molecules and carbonate ions, were found to be the main features of the microstructures. A recursive routine for generating and averaging supercells of stacking-faulted layered substances implemented in the TOPAS software was used to calculate diffraction patterns of the LDH phases as a function of the degree of faulting and to refine them against the measured diffraction data. The microstructures of the precursor materials were described by a model containing three parameters: transition probabilities for generating CdCl2-type and CrOOH-type faults and a transition probability for the random intercalation of water/carbonate layers. Automated series of simulations and refinements were performed, in which the transition probabilities were modified incrementally and thus the microstructures optimized by a grid search. All samples were found to exhibit the same fraction of CdCl2-type and CrOOH-type stacking faults, which indicates that they have identical Ni, Co and Al contents. Different degrees of interstratification faulting were determined, which could be correlated to different heights of intercalation-water-related mass-loss steps in the thermal analyses.

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The critical role of point defects in improving the specific capacitance of δ-MnO2 nanosheets

et al. 2017

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3D porous nanostructures built from 2D δ-MnO2 nanosheets are an environmentally friendly and industrially scalable class of supercapacitor electrode material. While both the electrochemistry and defects of this material have been studied, the role of defects in improving the energy storage density of these materials has not been addressed. In this work, δ-MnO2 nanosheet assemblies with 150 m2 g−1 specific surface area are prepared by exfoliation of crystalline KxMnO2 and subsequent reassembly. Equilibration at different pH introduces intentional Mn vacancies into the nanosheets, increasing pseudocapacitance to over 300 F g−1, reducing charge transfer resistance as low as 3 Ω, and providing a 50% improvement in cycling stability. X-ray absorption spectroscopy and high-energy X-ray scattering demonstrate a correlation between the defect content and the improved electrochemical performance. The results show that Mn vacancies provide ion intercalation sites which concurrently improve specific capacitance, charge transfer resistance and cycling stability.

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X-ray and neutron total scattering analysis of H_y·(Bi_0.2Ca_0.55Sr_0.25)(Ag_0.25Na_0.75)Nb₃O₁₀·xH₂O perovskite nanosheet booklets with stacking disorder

Cited by 3 publications

References 34 publications

Anionic Redox Topochemistry for Materials Design: Chalcogenides and Beyond

Anionic Redox Topochemistry for Materials Design: Chalcogenides and Beyond

A routine for the determination of the microstructure of stacking-faulted nickel cobalt aluminium hydroxide precursors for lithium nickel cobalt aluminium oxide battery materials

The critical role of point defects in improving the specific capacitance of δ-MnO2 nanosheets

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