Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Defects, Dopants and Sodium Mobility in Na₂MnSiO₄.

ABSTRACT: Sodium manganese orthosilicate, Na₂MnSiO₄, is a promising positive electrode material in rechargeable sodium ion batteries. Atomistic scale simulations are used to study the defects, doping behaviour and sodium migration paths in Na₂MnSiO₄. The most favourable intrinsic defect type is the cation anti-site (0.44?eV/defect), in which, Na and Mn exchange their positions. The second most favourable defect energy process is found to be the Na Frenkel (1.60?eV/defect) indicating that Na diffusion is assisted by the formation of Na vacancies via the vacancy mechanism. Long range sodium paths via vacancy mechanism were constructed and it is confirmed that the lowest activation energy (0.81?eV) migration path is three dimensional with zig-zag pattern. Subvalent doping by Al on the Si site is energetically favourable suggesting that this defect engineering stratergy to increase the Na content in Na₂MnSiO₄ warrants experimental verification.

SUBMITTER: Kuganathan N

PROVIDER: S-EPMC6168608 | biostudies-literature | 2018 Oct

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Publications

Defects, Dopants and Sodium Mobility in Na2MnSiO4.

Kuganathan Navaratnarajah N Chroneos Alexander A

Scientific reports 20181002 1

Sodium manganese orthosilicate, Na2MnSiO4, is a promising positive electrode material in rechargeable sodium ion batteries. Atomistic scale simulations are used to study the defects, doping behaviour and sodium migration paths in Na2MnSiO4. The most favourable intrinsic defect type is the cation anti-site (0.44 eV/defect), in which, Na and Mn exchange their positions. The second most favourable defect energy process is found to be the Na Frenkel (1.60 ...[more]

PMID: 30279505

Similar Datasets

Defects, Lithium Mobility and Tetravalent Dopants in the Li3NbO4 Cathode Material.

Project description:The defect processes of oxides such as self-diffusion impact their performance in electrochemical devices such as batteries and solid oxide fuel cells. The performance of lithium ion batteries can be improved by increasing the Li-ion diffusion. In that respect Li3NbO4 is identified as a positive electrode material for rechargeable lithium ion batteries. Here, we employ static atomistic scale simulations to examine the defect properties, doping behaviour and lithium ion migration paths in Li3NbO4. The present calculations show a correct reproduction of experimentally observed crystal structure of Li3NbO4. The Li-Nb anti-site defect is found to be the dominant intrinsic defect process suggesting that a small concentration of Li on Nb sites and Nb on Li sites is present. Vacancy assisted long range lithium diffusion paths were examined and our calculations reveal that the lowest activation energy (1.13 eV) migration path is two dimensional forming a zig-zag shape. Subvalent doping by Ge on the Nb site is thermodynamically favourable process and a potential strategy to incorporate extra Li in the form of Li interstitial in Li3NbO4. The results presented herein can motivate further experimental work for the development of Li3NbO4 based batteries.

| S-EPMC6379435 | biostudies-literature

Defects, dopants and Mg diffusion in MgTiO3.

Project description:Magnesium titanate is technologically important due to its excellent dielectric properties required in wireless communication system. Using atomistic simulation based on the classical pair potentials we study the defect chemistry, Mg and O diffusion and a variety of dopant incorporation at Mg and Ti sites. The defect calculations suggest that cation anti-site defect is the most favourable defect process. The Mg Frenkel is the second most favourable intrinsic defect though the formation energy is highly endoergic. Higher overall activation energies (>3 eV) are observed for oxygen migration compared to those observed for magnesium (0.88 eV). Dopant substitution energies for a range of cations with charges varying from +2 to +4 were examined. Divalent dopants (Mn2+, Fe2+, Co2+, Ca2+ and Zn2+) on the Mg site exhibit low solution energies. Trivalent dopants prefer to occupy Mg site though their solution energies are high. Exothermic solution energies calculated for tetravalent dopants (Ge4+ and Si4+) on the Ti site suggest the necessity of experimental verification.

| S-EPMC6416248 | biostudies-literature

Defects, Dopants and Lithium Mobility in Li 9 V 3 (P 2 O 7 ) 3 (PO 4 ) 2.

Project description:Layered Li9V3(P2O7)3(PO4)2 has attracted considerable interest as a novel cathode material for potential use in rechargeable lithium batteries. The defect chemistry, doping behavior and lithium diffusion paths in Li9V3(P2O7)3(PO4)2 are investigated using atomistic scale simulations. Here we show that the activation energy for Li migration via the vacancy mechanism is 0.72?eV along the c-axis. Additionally, the most favourable intrinsic defect type is Li Frenkel (0.44?eV/defect) ensuring the formation of Li vacancies that are required for Li diffusion via the vacancy mechanism. The only other intrinsic defect mechanism that is close in energy is the formation of anti-site defect, in which Li and V ions exchange their positions (1.02?eV/defect) and this can play a role at higher temperatures. Considering the solution of tetravalent dopants it is calculated that they require considerable solution energies, however, the solution of GeO2 will reduce the activation energy of migration to 0.66?eV.

| S-EPMC5970228 | biostudies-literature

KV4.3 Expression Modulates NaV1.5 Sodium Current.

Project description:In cardiomyocytes, the voltage-gated transient outward potassium current (Ito) is responsible for the phase-1 repolarization of the action potential (AP). Gain-of-function mutations in KCND3, the gene encoding the Ito carrying KV4.3 channel, have been associated with Brugada syndrome (BrS). While the role of Ito in the pro-arrhythmic mechanism of BrS has been debated, recent studies have suggested that an increased Ito may directly affect cardiac conduction. However, the effects of an increased Ito on AP upstroke velocity or sodium current at the cellular level remain unknown. We here investigated the consequences of KV4.3 overexpression on NaV1.5 current and consequent sodium channel availability. We found that overexpression of KV4.3 protein in HEK293 cells stably expressing NaV1.5 (HEK293-NaV1.5 cells) significantly reduced NaV1.5 current density without affecting its kinetic properties. In addition, KV4.3 overexpression decreased AP upstroke velocity in HEK293-NaV1.5 cells, as measured with the alternating voltage/current clamp technique. These effects of KV4.3 could not be explained by alterations in total NaV1.5 protein expression. Using computer simulations employing a multicellular in silico model, we furthermore demonstrate that the experimentally observed increase in KV4.3 current and concurrent decrease in NaV1.5 current may result in a loss of conduction, underlining the potential functional relevance of our findings. This study gives the first proof of concept that KV4.3 directly impacts on NaV1.5 current. Future studies employing appropriate disease models should explore the potential electrophysiological implications in (patho)physiological conditions, including BrS associated with KCND3 gain-of-function mutations.

| S-EPMC5857579 | biostudies-literature

Intrinsic Defects and Their Role in the Phase Transition of Na-Ion Anode Na2Ti3O7.

Project description:The development of high-power anode materials for Na-ion batteries is one of the primary obstacles due to the growing demands for their use in the smart grid. Despite the appealingly low cost and non-toxicity, Na2Ti3O7 suffers from low electrical conductivity and poor structural stability, which restricts its use in high-power applications. Viable approaches for overcoming these drawbacks reported to date are aliovalent doping and hydrogenation/hydrothermal treatments, both of which are closely intertwined with native defects. There is still a lack of knowledge, however, of the intrinsic defect chemistry of Na2Ti3O7, which impairs the rational design of high-power titanate anodes. Here, we report hybrid density functional theory calculations of the native defect chemistry of Na2Ti3O7. The defect calculations show that the insulating properties of Na2Ti3O7 arise from the Na and O Schottky disorder that act as major charge compensators. Under high-temperature hydrogenation treatment, these Schottky pairs of Na and O vacancies become dominant defects in Na2Ti3O7, triggering the spontaneous partial phase transition to Na2Ti6O13 and improving the electrical conductivity of the composite anode. Our findings provide an explanation on the interplay between intrinsic defects, structural phase transitions, and electrical conductivity, which can aid understanding of the properties of composite materials obtained from phase transitions.

| S-EPMC9832431 | biostudies-literature

Na3SbSe4-xS x as Sodium Superionic Conductors.

Project description:Na based all-solid-state batteries are a promising technology for large-scale energy storage applications owing to good safety properties and low cost. High performance solid electrolyte materials with high room temperature ionic conductivity, good electrochemical stability and facile synthesis are highly desired for the commercialization of this technology. In this work, we report the synthesis and characterization of a novel fast Na-ion conductor, cubic Na3SbSe4, with an excellent ionic conductivity of 0.85 mS cm-1 at room temperature, and a group of S doped variants. Na3SbSe4 exhibits good compatibility with metallic Na and good stability in a wide voltage range. The application of this compound as solid electrolyte is demonstrated in all-solid-state Na-ion cells cycled at room temperature.

| S-EPMC6002371 | biostudies-literature

Development of high-affinity nanobodies specific for NaV1.4 and NaV1.5 voltage-gated sodium channel isoforms.

Project description:Voltage-gated sodium channels, NaVs, are responsible for the rapid rise of action potentials in excitable tissues. NaV channel mutations have been implicated in several human genetic diseases, such as hypokalemic periodic paralysis, myotonia, and long-QT and Brugada syndromes. Here, we generated high-affinity anti-NaV nanobodies (Nbs), Nb17 and Nb82, that recognize the NaV1.4 (skeletal muscle) and NaV1.5 (cardiac muscle) channel isoforms. These Nbs were raised in llama (Lama glama) and selected from a phage display library for high affinity to the C-terminal (CT) region of NaV1.4. The Nbs were expressed in Escherichia coli, purified, and biophysically characterized. Development of high-affinity Nbs specifically targeting a given human NaV isoform has been challenging because they usually show undesired crossreactivity for different NaV isoforms. Our results show, however, that Nb17 and Nb82 recognize the CTNaV1.4 or CTNaV1.5 over other CTNav isoforms. Kinetic experiments by biolayer interferometry determined that Nb17 and Nb82 bind to the CTNaV1.4 and CTNaV1.5 with high affinity (KD ∼ 40-60 nM). In addition, as proof of concept, we show that Nb82 could detect NaV1.4 and NaV1.5 channels in mammalian cells and tissues by Western blot. Furthermore, human embryonic kidney cells expressing holo NaV1.5 channels demonstrated a robust FRET-binding efficiency for Nb17 and Nb82. Our work lays the foundation for developing Nbs as anti-NaV reagents to capture NaVs from cell lysates and as molecular visualization agents for NaVs.

| S-EPMC8935509 | biostudies-literature

Comparison of Magnetic Deflection among Neutral Sodium-Doped Clusters: Na(H2O)n, Na(NH3)n, Na(MeOH)n, and Na(DME)n.

Project description:Using a pulsed Stern-Gerlach deflection experiment, we present the results of a comparative study on the magnetic properties of neutral sodium-doped solvent clusters Na(Sol)n with n = 1-4 (Sol: H2O, NH3, CH3OH, CH3OCH3). Experimental deflection ratios are compared with values calculated from molecular dynamics simulations. NaNH3 and NaH2O are deflected as a spin 1/2 system, consistent with spin transitions occurring on a time scale significantly longer than 100 μs. For all other clusters, reduced deflection is observed. The observed magnetic deflection behavior is correlated to the number of thermally populated rotational states in the clusters. We discuss that spin-rotational couplings allow for avoided crossings and a reduction in the effective magnetic moment of the cluster. This work attempts to understand the evolution of magnetic properties in isolated weakly bound clusters and is relevant to diamagnetic and paramagnetic species expected to exist in solvated electron systems.

| S-EPMC10591511 | biostudies-literature

Defects, Diffusion, and Dopants in Li2Ti6O13: Atomistic Simulation Study.

Project description:In this study, force field-based simulations are employed to examine the defects in Li-ion diffusion pathways together with activation energies and a solution of dopants in Li2Ti6O13. The lowest defect energy process is found to be the Li Frenkel (0.66 eV/defect), inferring that this defect process is most likely to occur. This study further identifies that cation exchange (Li-Ti) disorder is the second lowest defect energy process. Long-range diffusion of Li-ion is observed in the bc-plane with activation energy of 0.25 eV, inferring that Li ions move fast in this material. The most promising trivalent dopant at the Ti site is Co3+, which would create more Li interstitials in the lattice required for high capacity. The favorable isovalent dopant is the Ge4+ at the Ti site, which may alter the mechanical property of this material. The electronic structures of the favorable dopants are analyzed using density functional theory (DFT) calculations.

| S-EPMC6766017 | biostudies-literature

Differential binding of tetrodotoxin and its derivatives to voltage-sensitive sodium channel subtypes (Nav 1.1 to Nav 1.7).

Project description:Background and purposeThe development of subtype-selective ligands to inhibit voltage-sensitive sodium channels (VSSCs) has been attempted with the aim of developing therapeutic compounds. Tetrodotoxin (TTX) is a toxin from pufferfish that strongly inhibits VSSCs. Many TTX analogues have been identified from marine and terrestrial sources, although their specificity for particular VSSC subtypes has not been investigated. Herein, we describe the binding of 11 TTX analogues to human VSSC subtypes Nav 1.1-Nav 1.7.Experimental approachEach VSSC subtype was transiently expressed in HEK293T cells. The inhibitory effects of TTX analogues on each subtype were assessed using whole-cell patch-clamp recordings.Key resultsThe inhibitory effects of TTX on Nav 1.1-Nav 1.7 were observed in accordance with those reported in the literature; however, the 5-deoxy-10,7-lactone-type analogues and 4,9-anhydro-type analogues did not cause inhibition. Chiriquitoxin showed less binding to Nav 1.7 compared to the other TTX-sensitive subtypes. Two amino acid residues in the TTX binding site of Nav 1.7, Thr1425 and Ile1426 were mutated to Met and Asp, respectively, because these residues were found at the same positions in other subtypes. The two mutants, Nav 1.7 T1425M and Nav 1.7 I1426D, had a 16-fold and 5-fold increase in binding affinity for chiriquitoxin, respectively.Conclusions and implicationsThe reduced binding of chiriquitoxin to Nav 1.7 was attributed to its C11-OH and/or C12-NH2 , based on reported models for the TTX-VSSC complex. Chiriquitoxin is a useful tool for probing the configuration of the TTX binding site until a crystal structure for the mammalian VSSC is solved.

| S-EPMC5647187 | biostudies-literature