Layer Of Na Research Articles

A first-principles research on the properties of two-dimensional penta-BP2 as an anode material for both Na and K ion batteries

The escalating demand for large-scale energy storage solutions has sparked significant interest in metal-ion batteries, particularly in the realm of high-performance anode materials. This work explores the potential of penta-BP2 as an anode material for sodium and potassium-ion batteries through first-principles calculations. The two-dimensional metallic structure of penta-BP2 exhibits favorable electrical conductivity, making it an ideal candidate for anode materials. Theoretical analysis reveals that penta-BP2 can adsorb two layers of Na and three layers of K, resulting in high storage capacities of 1105 and 1473 mAh/g, along with low open-circuit voltages of 0.40 and 0.30 V, respectively. These characteristics enable the production of high energy density in sodium and potassium-ion batteries. Additionally, the material's small Young's modulus and low diffusion energy barriers further establish penta-BP2 as a flexible anode material capable of rapid charge/discharge processes.

First-Principles Calculations of TiB4 and TiB5 as Anodes with High Capacity for Na-Ion Batteries.

The electrochemical properties of TiB4 and TiB5 monolayers in Na-ion batteries (NIBs) were studied by using the first-principles calculation method based on density functional theory. The TiB4/TiB5 monolayer showed excellent Na storage capacity, capable of adsorbing two layers of Na with theoretical capacities of 1176.77 and 1052.05 mA g-1, respectively. The average operating voltages of the TiB4 and TiB5 monolayers are 0.073 and 0.042 eV, respectively, indicating that they can be used as anode materials for NIBs. More interestingly, the exposed B surface not only brings a high theoretical capacity but also provides a relatively small diffusion barrier of 0.16 (for TiB4) and 0.33 eV (for TiB5), enhancing their rate capability in NIBs.

First principles study of S-repaired ultra-thin InSe electrodes for ion storage and transport

We revealed an interesting S-repaired InSe monolayer toward its performance of ion batteries using first principles calculations. The Li/Na/Mg/K ion prefers to occupy the hollow site. It exhibits a lower diffusion barrier for Na, Mg and K ion than that of Li ion. It was also found that a transition from the semiconducting to metallic nature after Li/Na/K adsorption. S-repaired InSe monolayer can accommodate up to two layers of Na corresponding to the maximum capacity of 654 mAhg−1. Our study elaborated the effectiveness of surface modification design for exploring electrode materials combined the factor of environmental stability.

Molecular insights on Ca2+/Na+ separation via graphene-based nanopores: The role of electrostatic interactions to ionic dehydration

Ca 2+ /Na + separation is a common problem in industrial applications, biological and medical fields. However, Ca 2+ and Na + have similar ionic radii and hydration radii, thus Ca 2+ /Na + separation is challenging. Inspired by biological channels, group modification is one of the effective methods to improve the separation performance. In this work, molecular dynamics simulations were performed to investigate the effects of different functional groups (COO − , NH 3 + ) on the separation performance of Ca 2+ and Na + through graphene nanopores under an electric field. The pristine graphene nanopore was used for comparison. Results showed that three types of nanopores preferred Ca 2+ to Na + , and Ca 2+ /Na + selectivity followed the order of GE-COO − (4.06) > GE (1.85) > GE-NH 3 + (1.63). Detailed analysis of ionic hydration microstructure shows that different nanopores result in different hydration factors for the second hydration layer of Ca 2+ and the first layer of Na + . Such different hydration factors corresponding to the dehydration ability can effectively evaluate the separation performance. In addition, the breaking of hydrogen bonds between water molecules due to electrostatic effects can directly affect the dehydration ability. Therefore, the electrostatic effect generated by group modification will affect the ionic hydration microstructure, thus reflecting the differences in dehydration ability. This in turn affects the permeable and separation performance of cations. The results of this work provide perceptive guidelines for the application of graphene-based membranes in ion separation.

The material composition and characteristics of bentonite clays for use as a binder in the production of iron ore pellets

The bentonite clays used in the production of iron ore pellets at metallurgical plants of Russia and Ukraine are analyzed. According to the composition of the exchange complexes, clay is divided into alkaline, where more than half of the components of the exchange complex are sodium and potassium cations (Na++K+, mEq per 100 g of clay) and alkaline-earth (calcium, magnesium, calcium-magnesium and magnesium-calcium), where more than half of the exchangeable cations belong to calcium and magnesium (Ca+++Mg++, mEq per 100 g of clay). The reserves of alkaline-earth bentonite clays of the Cherkassk deposit are the largest in the CIS. The mineralogical and chemical compositions, as well as the size and composition of the exchange complex of these bentonite clays, are analyzed. Clays are fundamentally suitable for the production of pellets under certain conditions and are located near the surface of the earth in three (II, III and IV) layers of the productive stratum. The II layer contains mainly Ca++ ions and substantially less Mg++ in the exchange complex; the III layer consists of the palygorskite mineral, which contains mainly Mg++ ions in the exchange complex, substantially less than Ca++ and more than in the II layer of Na+ ions; the IV layer is a natural mixture of II and III layers in a ratio of an average of about 1:1. Palygorskite and montmorillonite in the IV layer of the Cherkassk deposit create a high-quality dispersion both in the sense of colloidal and structural-mechanical properties of the suspension, which is also a favorable factor in the interaction of particles of the strengthening additive with particles of the concentrate. The analysis of strength indicators of pellets using bentonites with alkaline and alkaline-earth exchange complex is presented. It was shown that despite the low swelling of alkaline-earth bentonites, the quality of pellets with these bentonites, in some cases, is insignificant, and in certain conditions is not inferior to the quality of pellets with alkaline bentonites at the same flow rate

Adsorption mechanisms of Mo2CrC2 MXenes as potential anode materials for metal-ion batteries: A first-principles investigation

Two dimensional MXene are attracting increasing interests as electrode materials for metal ion batteries (MIBs) because metal ions can diffuse in a 2D lattice surface. In this work, first-principles calculations were carried out to investigate the adsorption performance of monolayer Mo2CrC2 for Li, Na, and K. The results show strong storage ability for various metal cations. There are three layers of Li, two layers of Na, one layer of K, and four layers of Mg on both sides of the monolayer. The electrochemical and thermodynamics of the intercalation of metal ions on the Mo2CrC2 Mxene have been intensively investigated. There is no band gap at the Fermi level of any configuration indicating that it has excellent electronic conductivity leading to an asymmetric electron localization distribution. The binding energy of metal ions decreases as the ion concentration increases. The adsorption of metal ions on a mono-layer of Mo2CrC2 has been studied, and the results indicate that the metal ions obviously improved the diffusion of metal ions. The CI-NEB method was used to study the diffusion of a cation on a Mo2CrC2 surface and search for its lowest energy along the diffusion pathway. Their structural transformations were studied via ab initio molecular dynamic (AIMD) simulations at a series of temperatures. The metal ions gradually evolved via thermal motion with increasing temperature. These results suggest that Mo2CrC2 could be a promising electrode material for Li- and Na-ion batteries in terms of Mo2CrC2 specific capacity, diffusion dynamics, and structural stability.

Potential Applications of Heterostructures of TMDs with MXenes in Sodium-Ion and Na-O2 Batteries.

Na-ion batteries are viewed as the alternative to Li-ion batteries for similar electrochemical properties, while they always suffer from a low capacity. Na-O2 batteries are important due to their high energy density; however, they are usually limited by high overpotential. In this manuscript, 16 different heterostructures of TMDs with MXenes (bare and O-terminated case) are constructed and their potential in the application of sodium-ion batteries (SIBs) and Na-O2 batteries is explored. Among these structures, it is proved that only the heterostructures of VS2 with O-terminated MXenes could load five layers of Na+ ions, while the others will have a distortion when Na+ ions intercalate or diffuse in the interlayer or the second adsorption layer. The ultrasmall diffusion barrier of Na+ ion denotes that these structures have a fast charge/discharge speed, and the ultrasmall open circuit voltages (OCVs) of 0.18 and 0.21 V prove that they are promising candidates for SIBs. The ultralow overpotential 0.55 V/0.20 V for the ηORR/ηOER means that the O facet of the VS2/Ti2CO2 heterostructure also has a great potential in the application of Na-O2 batteries. These simulations prove that the heterostructures constructed by TMDs with MXenes have great potential in SIBs and Na-O2 batteries and are important for future battery design.

From structure topology to chemical composition. XXV: new insights into the close packing of cations in the structures of the seidozerite-supergroup TS-block minerals

Abstract The titanium-silicate (TS) block is the main structural unit in the 45 seidozerite-supergroup minerals; it consists of a central O (O=Octahedral) sheet and two adjacent H (H=Heteropolyhedral) sheets where Si2O7 groups occur in the H sheets. The three HOH sheets of the TS block form a three-layered close packing of cations with an ABC repeat; mean cation–cation distances are 3.41 Å. Minerals of the seidozerite supergroup are divided into four groups based on the content of Ti and topology and stereochemistry of the TS block: in rinkite, bafertisite, lamprophyllite and murmanite groups, Ti (+Nb+Zr+Fe3++Mg+Mn)=1, 2, 3 and 4 apfu, respectively. All TS-block structures consist either solely of TS blocks or of two types of block: the TS block and an I (intermediate) block that comprises atoms between two TS blocks. The TS block propagates close packing of cations into the I block. There are two types of close-packed layers of cations in the I block: (I) a layer of Na+ and P5+ with mean cation–cation distances of 3.41 Å and (II) a layer of Ba2+ (+K+, Sr2+ and Na+) with mean cation–cation distances of 4.73 Å. The general topology of the TS block is independent of the topology and chemical composition of the I block. However direct interaction between TS and I blocks takes place in the crystal structures of jinshajiangite, bobshannonite, bafertisite, hejtmanite, delindeite and cámaraite. Interaction of Ba atoms in the I block and F (+O) atoms of the TS block results in doubling of the minimal translations, 2t 1 and 2t 2, and a concomitant change in symmetry of the structure from primitive to C-centered.

First-principles study of fast Na diffusion in Na3P

We investigate the ionic conductivity and electronic properties of Na3P using first principle simulations. We found that the atoms were arranged in one layer of Na and P atoms and alternate layers containing Na atoms only. Three possible independent and asymmetric Na diffusion paths exist. In the first two, Na diffusion occurs among sodium atoms in the same layer, while in the third path, Na diffusion occurs among sodium atoms in different layers. Moreover, the activation energies of Na diffusion in the first two paths are much smaller than that of the third. With the introduction of a Na vacancy, a hole state deep in the valence region appears that is responsible for the valence band-edge rising in the center of the Brillouin zone. This sodium vacancy is very likely to play a role in the electron transfer in Na3P. The fast ionic conductivity and considerable electron conductivity make P a promising anode material in the first step of the Na deintercalation process.

Resolving the strange behavior of extraterrestrial potassium in the upper atmosphere

AbstractIt has been known since the 1960s that the layers of Na and K atoms, which occur between 80 and 105 km in the Earth's atmosphere as a result of meteoric ablation, exhibit completely different seasonal behavior. In the extratropics Na varies annually, with a pronounced wintertime maximum and summertime minimum. However, K varies semiannually with a small summertime maximum and minima at the equinoxes. This contrasting behavior has never been satisfactorily explained. Here we use a combination of electronic structure and chemical kinetic rate theory to determine two key differences in the chemistries of K and Na. First, the neutralization of K+ ions is only favored at low temperatures during summer. Second, cycling between K and its major neutral reservoir KHCO3 is essentially temperature independent. A whole atmosphere model incorporating this new chemistry, together with a meteor input function, now correctly predicts the seasonal behavior of the K layer.

Electron injection barrier reduction for organic light-emitting devices by quinacridone derivatives

Water/alcohol-soluble quinacridone derivatives have been synthesized and utilized as an electron injection layer in organic light-emitting diodes. Initial results are very promising, as a device with a layer of Na(+)QHSO(3)(-) adjacent to an Al cathode exhibited a luminance efficiency (1.65 cd A(-1)) that was significantly enhanced relative to the efficiency (0.85 cd A(-1)) of a control device with an unstable, lower work function Ba/Al cathode.

Electron-stimulated desorption of sodium atoms initiated by their reverse motion

This paper reports on the first measurement of the yield and energy distributions of sodium atoms in electron-stimulated desorption at T = 160 K from sodium layers adsorbed on tungsten with a gold film atop. The Na atom yield has a resonant pattern with an appearance threshold of 30 eV, which can be attributed to exciton excitation in the Na 2p level. The Na yield is associated with the formation of a semiconducting NaxAuy film at T ∼ 300 K and sodium and gold coverages in excess of one monolayer. Sodium atoms are desorbed through Auger neutralization of Na2+ ions in their reverse motion toward the surface and is limited by the resonant ionization of Na atoms as they pass through the adsorbed layer of Na+ ions. The energy distributions of Na atoms are bell shaped with a maximum at about 0.56 eV.

Na 2TiGeO 5: Crystal structure stability at low temperature and high pressure

The temperature evolution of the lattice parameters measured from 295 to 125 K exhibits a small instability below T c≈278 K, indicating ferroelastic properties of Na 2TiGeO 5. The behavior is related to the specific crystal structure built of polyhedral layers with shared TiO 5 pyramids and GeO 4 tetrahedra, alternating with layers of Na + cations. Antiparallel alignment of the short apical titanyl bond in adjacent rows of the polyhedral layer gives rise to spontaneous strain, when a distortion of the TiO 5 groups occurs. Single-crystal structures determined at room temperature and 120 K suggest that {1 1 0} domains, developing below T c, entail a tetragonal-to-orthorhombic symmetry change. The mechanism is attributed to a shortening of the O–O distance between the polyhedral layers, and to minor shifts of the positions of the Ti atoms and the correlated oxygen atoms along the c-axis. The structure distortion, however, is too small to allow any unambiguous determination of the symmetry-breaking effects. The bulk modulus and its pressure derivative have been determined as B 0=89(2) GPa and B 0 ′ = 4.0 . A pressure-induced phase transformation takes place at P c≈12.5 GPa, presumably to an orthorhombic structure. The pressure effect on the transition temperature is given by Δ T c/Δ P≈1.76 K/GPa.

The First Molecular Charge Transfer Salt Containing Layers of an Alkali Metal

We report the first molecular charge transfer salt containing layers of Na+ within its lattice. From the crystal structure and from C=C and C-S bond lengths and Raman stretching frequencies we obtain a formula a′"-(BEDT-TTF)9[Fe(C2O4)3]8Na18(H2O)24. The structure consists of alternating layers of BEDT-TTF, and layers comprising [Fe(C2O4)3]3−, Na+ and H2O. The packing of the layers follows the sequence ABCDABCDA as previously seen in the compound β″-(BEDT-TTF)4[Fe(C2O4)3]2.C12O6H24.9HxO1.

Preparation, crystal structure and characterization of α-NaSbP2S6 and β-NaSbP2S6 phases

The new phases α-NaSbP2S6 and β-NaSbP2S6 were synthesized by ceramic and reactive flux methods at 773K. The structures of α-NaSbP2S6 and β-NaSbP2S6 were determined by the single-crystal X-ray diffraction technique. α-NaSbP2S6 crystallizes in the monoclinic space group P21/c with a=11.231(2)Å, b=7.2807(15)Å, c=11.640(2)Å, β=108.99(3)°, V=900.0(3)Å3 and z=4. β-NaSbP2S6 crystallizes in the monoclinic space group P21 with a=6.6167(13)Å, b=7.3993(15)Å, c=9.895(2)Å, β=92.12(3) °, V=484.10(17)Å3 and z=2.The α- and β-phases of NaSbP2S6 are closely related, the main difference lies in the stacking of the [Sb[P2S6]]nn− layers. The structure of α-NaSbP2S6 consists of two condensed layers (MPS3 type) to give an ABAB… sequence with Na+ cations located in the interlayer space. The packing of β-NaSbP2S6 is formed by monolayers of [Sb[P2S6]]nn− stacked in an AA… fashion separated by a layer of Na+ cations. Both phases are derivates of the M1+M3+P2Q6 family.The optical band gaps of α-NaSbP2S6 and β-NaSbP2S6 were determined by UV–vis diffuse reflectance measurements to be 2.17 and 2.25eV, respectively.

Polymer-layered silicate nanocomposites. 1. A study of poly(ethylene oxide)/Na +-montmorillonite nanocomposites as polyelectrolytes and polyethylene-block-poly(ethylene glycol) copolymer/Na +-montmorillonite nanocomposites as fillers for reinforcement of polyethylene

Poly(ethylene oxide) PEO/Na +-montmorillonite and polyethylene–poly(ethylene glycol) (PE–PEG) diblock copolymer/Na +-montmorillonite nanocomposites have been prepared by melt intercalation method. The effect of thermal treatment on the amount of PEO and PE–PEG diblock copolymer intercalated into layers of Na +-montmorillonite and on ionic conductivity of PEO/Na +-MMT nanocomposites have been evaluated. It was found that PEO can be intercalated into the layers of Na +-MMT by simple mechanical blending and part of PE in PE–PEG diblock copolymers was also intercalated into the layers of Na +-MMT. The intercalated amount increases with thermal treatment time, which improves the ionic conductivity of the PEO/Na +-MMT nanocomposites. PE–PEG diblock copolymer/Na +-MMT hybrids can be considered as a new kind of fillers for the reinforcement of polyethylene. By only adding a small amount (1–15% by weight) of these fillers, tensile strength of polyethylene was improved significantly. This research provides valuable information for the development of new kinds of fillers for polymer reinforcement, and polyelectrolytes.

Effect of dopant and clay on nanocomposites of polyaniline (PAN) intercalated into Na +-montmorillonite (Na +-MMT)

The nanocomposites of polyaniline (PAN) and Na + -montmorillonite (Na + - MMT) were synthesized by emulsion polymerization using dodecylbenzenesulfonic acid (DBSA) or camphorsulfonic acid (CSA) as dopant and emulsifier. In the X-ray diffraction patterns of the systems, we observed that the layer of conducting PAN-DBSA or PAN-CSA between the clay layers was in nanoscale layers (< 10 A). The temperature dependence of dc conductivity [σ dc (T)] for the nanocomposites followed a quasi-one dimensional (ID) variable range hopping (VRH) model. The σ dc (T) varied with the dopant used and the molar ratio. From temperature dependent EPR experiments, we obtained the magnetic susceptibility and the line width of the system. The Na + -MMT clay layer plays important role for interchain interaction of the system. The effects of dopant and the layer of Na + -MMT on charge transport and structure are discussed.

CO2/ SOx-sensors with different β“-aluminas as solid electrolytes

Sensors with solid electrolytes provide the possibility of correct and fast measurements of partial pressures of various gases. By modification of the solid electrolyte, sensors with specific performances may be manufactured. Layers of Na+-, Li+-, Ca2+- and Sr2+-β“-alumina on top of polycrystalline α-alumina substrates were produced by an in-situ formation process and were used as solid electrolytes for CO2 and SOx sensors. Carbonates and sulphates were applied as measuring electrodes and oxidic mixtures of SiO2 and silicates were used as reference electrodes. The different performance of these sensors was investigated over a wide temperature range and the results were compared with theoretical data. Different solid electrolyte / electrode combinations were applied, which all showed different characteristic cross sensitivities against water and organic components.

The crystal structure of voggite, a new hydrated Na–Zr hydroxide–phosphate–carbonate mineral

AbstractThe crystal structure of the new mineral voggite, Na2Zr(PO4)(CO3)(OH).2H2O , from the Francon quarry, Montreal, Quebec, Canada, has been solved in order to determine the correct chemical formula, as conventional electron microprobe methods were found unreliable. The unit cell is monoclinic, I2/m, with a = 12.261(2), b = 6.561(1), c = 11.757(2)Å, β = 116.19(2)°. The structure consists of layers of edge-sharing Zr-O pentagonal bipyramids, separated by layers of Na-(O,H2O) octahedra. The carbonate ion acts as a bidentate ligand in the Zr-O polyhedron, the third oxygen atom being bonded to the Na atom. The phosphate group is bonded to three different Zr atoms and to a Na atom. The Zr-O bond lengths vary from 2.067 to 2.283 (mean 2.140Å), while Na-O are between 2.304 and 2.773, (σ = 0.006Å, mean 2.480Å). The carbonate and phosphate bonds are normal. It is inferred from the structure that the columns of octahedrally coordinated Na atoms can easily be broken apart when subjected to the heat generated by the electron microprobe beam, with the subsequent expulsion of water. This gives rise to ‘mobile’ Na atoms, which make quantitative electron microprobe analysis extremely difficult. The structure allows the ‘liberated’ Na atoms to move freely within planes parallel to .

Aminosulfonic acids. Part 1. Crystal structures of N-methylaminomethanesulfonic acid, MeNHCH2SO3H, and disodium N-methyliminobis(methanesulfonate) dihydrate, MeN(CH2SO3Na)2•2H2O

The crystal structure of N-methylaminomethanesulfonic acid (P212121, a = 5.455(1) Å, b = 7.791(1) Å, c = 11.925(2) Å, Z = 4) consists of +MeNH2CH2SO3− zwitterions hydrogen-bonded to form infinite chains about screw axes parallel to a. In the structure of MeN(CH2SO3Na)2•2H2O (Pbcn, a = 10.469(1) Å, b = 6.039(3) Å, c = 17.549(3) Å, Z = 4), layers of MeN(CH2SO3−)2 anions alternate with layers of Na+ ions parallel to (001). The anions are linked by [Formula: see text] bonds between the water molecules and the O(2) atoms of the sulfonate groups. Because of the twofold orientational disorder of the N—CH3 groups the space group Pbcn is only statistical.The S—C, C—N, and S—O bond lengths in solid aminosulfonic acids and their salts are discussed with a view to detecting the existence of effects due to deprotonation of the amino group and to hydrogen bonding.