Browse
Submit Data
Databases
API
Help

Dataset Information

40 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Local structures around the substituted elements in mixed layered oxides.

ABSTRACT: The chemical substitution of a transition metal (M) is an effective method to improve the functionality of a material, such as its electrochemical, magnetic, and dielectric properties. The substitution, however, causes local lattice distortion because the difference in the ionic radius (r) modifies the local interatomic distances. Here, we systematically investigated the local structures in the pure (x?=?0.0) and mixed (x?=?0.05 or 0.1) layered oxides, Na(M1-xM'x)O2 (M and M' are the majority and minority transition metals, respectively), by means of extended X-ray absorption fine structure (EXAFS) analysis. We found that the local interatomic distance (dM-O) around the minority element approaches that around the majority element to reduces the local lattice distortion. We further found that the valence of the minority Mn changes so that its ionic radius approaches that of the majority M.

SUBMITTER: Akama S

PROVIDER: S-EPMC5333154 | biostudies-literature | 2017 Mar

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Publications

Local structures around the substituted elements in mixed layered oxides.

Akama Shota S Kobayashi Wataru W Amaha Kaoru K Niwa Hideharu H Nitani Hiroaki H Moritomo Yutaka Y

Scientific reports 20170302

The chemical substitution of a transition metal (M) is an effective method to improve the functionality of a material, such as its electrochemical, magnetic, and dielectric properties. The substitution, however, causes local lattice distortion because the difference in the ionic radius (r) modifies the local interatomic distances. Here, we systematically investigated the local structures in the pure (x = 0.0) and mixed (x = 0.05 or 0.1) layered oxides, Na(M1-xM'x)O2</s ...[more]

PMID: 28252008

Similar Datasets

Inhibition of oxygen dimerization by local symmetry tuning in Li-rich layered oxides for improved stability.

Project description:Li-rich layered oxide cathode materials show high capacities in lithium-ion batteries owing to the contribution of the oxygen redox reaction. However, structural accommodation of this reaction usually results in O-O dimerization, leading to oxygen release and poor electrochemical performance. In this study, we propose a new structural response mechanism inhibiting O-O dimerization for the oxygen redox reaction by tuning the local symmetry around the oxygen ions. Compared with regular Li2RuO3, the structural response of the as-prepared local-symmetry-tuned Li2RuO3 to the oxygen redox reaction involves the telescopic O-Ru-O configuration rather than O-O dimerization, which inhibits oxygen release, enabling significantly enhanced cycling stability and negligible voltage decay. This discovery of the new structural response mechanism for the oxygen redox reaction will provide a new scope for the strategy of enhancing the anionic redox stability, paving unexplored pathways toward further development of high capacity Li-rich layered oxides.

| S-EPMC7532436 | biostudies-literature

Synthesis of core-shell Ce-modified mixed metal oxides derived from P123-templated layered double hydroxides.

Project description:Layered double hydroxides are a promising platform material which can be combined with a variety of active species based on their characteristic features. Silicon@P123-templated Ce-doped layered double hydroxide (SiO2@CeMgAl-LDH(P123)) composites were synthesized via a facile in situ co-precipitation method, and characterized by TEM, X-ray diffraction, FTIR, XPS, CO2-, etc. in detail. Meanwhile, the calcined powder (SiO2@CeMgAl-LDO(P123)) possessed an excellent core-shell structure and a high surface area inherited from the LDH structure, which led to an outstanding catalytic activity (99.7% conversion of propylene oxide, 92.4% selectivity of propylene glycol methyl ether) under mild reaction conditions (120 °C). Cerium oxide provides a large number of oxygen vacancies and significantly improves the medium basic strength of the material, which facilitates the selective ring-opening of PO. Furthermore, the introduction and removal of P123 make the cerium oxide uniformly dispersed on the LDH layers, providing more reaction sites for the reaction of methanol and propylene oxide. The core-shell structure prepared by the in situ co-precipitation method could solve the shortcomings of agglomeration of layered double hydroxides and prolong the catalytic life evidently.

| S-EPMC8695133 | biostudies-literature

Nanoscale Hydration in Layered Manganese Oxides.

Project description:Birnessite is a layered MnO2 mineral capable of intercalating nanometric water films in its bulk. With its variable distributions of Mn oxidation states (MnIV, MnIII, and MnII), cationic vacancies, and interlayer cationic populations, birnessite plays key roles in catalysis, energy storage solutions, and environmental (geo)chemistry. We here report the molecular controls driving the nanoscale intercalation of water in potassium-exchanged birnessite nanoparticles. From microgravimetry, vibrational spectroscopy, and X-ray diffraction, we find that birnessite intercalates no more than one monolayer of water per interlayer when exposed to water vapor at 25 °C, even near the dew point. Molecular dynamics showed that a single monolayer is an energetically favorable hydration state that consists of 1.33 water molecules per unit cell. This monolayer is stabilized by concerted potassium-water and direct water-birnessite interactions, and involves negligible water-water interactions. Using our composite adsorption-condensation-intercalation model, we predicted humidity-dependent water loadings in terms of water intercalated in the internal and adsorbed at external basal faces, the proportions of which vary with particle size. The model also accounts for additional populations condensed on and between particles. By describing the nanoscale hydration of birnessite, our work secures a path for understanding the water-driven catalytic chemistry that this important layered manganese oxide mineral can host in natural and technological settings.

| S-EPMC7880569 | biostudies-literature

Formation of different shell structures in lithium-rich layered oxides and their influence on electrochemical properties.

Project description:A lithium-rich layered oxide with different shell structures was synthesized by a simple wet-chemical surface deposition method. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and other techniques were applied to characterize the crystal structure, morphology, and micro-structure of the samples. The surface of the lithium-rich layered oxide can successively produce island-like spinel, ultra-thin spinel, and thick two-phase (spinel and amorphous manganese oxides) separation shell layers with an increase in the coating amount. The formation process of the different shell structures and the effect of the shell structure on the lattice parameters were discussed. The different shell structures play an important role in the electrochemical performance of the lithium-rich oxide. In particular, when the coating amount is 1 wt%, the lithium-rich material with a uniform Li4Mn5O12 spinel shell layer exhibits superior electrochemical performance, and can maintain a discharge capacity of 209.9 mA h g-1 and 166.8 mA h g-1 at rates of 2C and 5C.

| S-EPMC9080639 | biostudies-literature

Sonication accelerated formation of Mg-Al-phosphate layered double hydroxide via sol-gel prepared mixed metal oxides.

Project description:Single-phase magnesium-aluminium layered double hydroxide (LDH) intercalated with dihydrogen phosphate was successfully produced by hydration of nanopowder of the respective mixed metal oxide (MMO) obtained using sol-gel based method followed by a two-step anion exchange hydroxide-to-chloride and chloride-to-phosphate. The MMO with the metal cation ratio of Mg/Al = 2:1 was prepared using the aqueous sol-gel method. Processes of the parent Mg2Al-OH LDH formation and the successive anion-exchanges, ОН- → Cl- and Cl- → H2PO4-, were considerably accelerated via the application of high-power (1.5 kW) ultrasound. The crystalline phases formed at all stages of the Mg2Al-H2PO4 LDH production were characterized using X-ray diffraction, scanning electron microscopy, scanning transmission electron microscopy, inductive coupled plasma optical emission spectroscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis. Based on the data of chemical analysis and the XRD data, the type of the intercalated phosphate anion was determined and the arrangement of this anion in the interlayer was modelled.

| S-EPMC6639339 | biostudies-literature

Local atomic arrangements and lattice distortions in layered Ge-Sb-Te crystal structures.

Project description:Insights into the local atomic arrangements of layered Ge-Sb-Te compounds are of particular importance from a fundamental point of view and for data storage applications. In this view, a detailed knowledge of the atomic structure in such alloys is central to understanding the functional properties both in the more commonly utilized amorphous-crystalline transition and in recently proposed interfacial phase change memory based on the transition between two crystalline structures. Aberration-corrected scanning transmission electron microscopy allows direct imaging of local arrangement in the crystalline lattice with atomic resolution. However, due to the non-trivial influence of thermal diffuse scattering on the high-angle scattering signal, a detailed examination of the image contrast requires comparison with theoretical image simulations. This work reveals the local atomic structure of trigonal Ge-Sb-Te thin films by using a combination of direct imaging of the atomic columns and theoretical image simulation approaches. The results show that the thin films are prone to the formation of stacking disorder with individual building blocks of the Ge2Sb2Te5, Ge1Sb2Te4 and Ge3Sb2Te6 crystal structures intercalated within randomly oriented grains. The comparison with image simulations based on various theoretical models reveals intermixed cation layers with pronounced local lattice distortions, exceeding those reported in literature.

| S-EPMC4879703 | biostudies-literature

Synthesis of Mg-Al Mixed Oxides with Markedly High Surface Areas from Layered Double Hydroxides with Organic Sulfonates.

Project description:Mg-Al mixed oxides with record-high surface areas and basic site concentrations were synthesized from Mg-Al layered double hydroxides with interlayer isethionate (Ise) or 3-hydroxy-1-propanesulfonate (HPS). Anion exchange of interlayer CO3 2- in synthetic hydrotalcites with the organic sulfonates induces disorders in layer stacking as characterized by powder X-ray diffraction and enables facile delamination in water. Thermal treatment of materials anion-exchanged by Ise (MgAl-Ise) and HPS (MgAl-HPS) in N2 and H2 resulted in the formation of Mg-Al mixed oxides with marked enhancement in Brunauer-Emmett-Teller (BET) surface area relative to those treated in air. Treatment in a flow of H2 is particularly effective, doubling the surface area of mixed oxides derived from MgAl-Ise relative to those obtained in a flow of N2. A higher degree of disorder in layer stacking in MgAl-HPS than MgAl-Ise resulted in the formation of Mg-Al mixed oxides with higher surface areas than those from MgAl-Ise. As a result, thermal activation of MgAl-HPS in a flow of H2 yielded Mg-Al mixed oxides with the highest BET surface area (410 m2 g-1) and CO2 uptake (1.6 mmol g-1 at 25 °C and 100 kPa) in all samples. These values are significantly higher than those obtained from the initial hydrotalcites as well as those reported in the literature with similar Mg-Al ratios. Investigation of the thermal activation steps by thermogravimetric analysis and mass spectrometry indicates that the key factors to achieve high surface area and CO2 uptake are to weaken interactions between layers by inducing stacking disorders and to facilitate the removal of interlayer sulfonates by preventing the formation of sulfates from them via thermal activation under a reducing environment.

| S-EPMC6643649 | biostudies-literature

Local atomic arrangements and lattice distortions in layered Ge-Sb-Te crystal structures.

| S-EPMC4879703 | biostudies-other

Elucidating anionic oxygen activity in lithium-rich layered oxides.

Project description:Recent research has explored combining conventional transition-metal redox with anionic lattice oxygen redox as a new and exciting direction to search for high-capacity lithium-ion cathodes. Here, we probe the poorly understood electrochemical activity of anionic oxygen from a material perspective by elucidating the effect of the transition metal on oxygen redox activity. We study two lithium-rich layered oxides, specifically lithium nickel metal oxides where metal is either manganese or ruthenium, which possess a similar structure and discharge characteristics, but exhibit distinctly different charge profiles. By combining X-ray spectroscopy with operando differential electrochemical mass spectrometry, we reveal completely different oxygen redox activity in each material, likely resulting from the different interaction between the lattice oxygen and transition metals. This work provides additional insights into the complex mechanism of oxygen redox and development of advanced high-capacity lithium-ion cathodes.

| S-EPMC5838240 | biostudies-literature

Two-dimensional type-II Dirac fermions in layered oxides.

Project description:Relativistic massless Dirac fermions can be probed with high-energy physics experiments, but appear also as low-energy quasi-particle excitations in electronic band structures. In condensed matter systems, their massless nature can be protected by crystal symmetries. Classification of such symmetry-protected relativistic band degeneracies has been fruitful, although many of the predicted quasi-particles still await their experimental discovery. Here we reveal, using angle-resolved photoemission spectroscopy, the existence of two-dimensional type-II Dirac fermions in the high-temperature superconductor La1.77Sr0.23CuO4. The Dirac point, constituting the crossing of [Formula: see text] and [Formula: see text] bands, is found approximately one electronvolt below the Fermi level (EF) and is protected by mirror symmetry. If spin-orbit coupling is considered, the Dirac point degeneracy is lifted and the bands acquire a topologically non-trivial character. In certain nickelate systems, band structure calculations suggest that the same type-II Dirac fermions can be realised near EF.

| S-EPMC6092334 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data