Study on Lithium Insertion in Lepidocrocite and ,λ-MnO2 Type TiO2： A First-Principles Prediction

TiO2 is a latent anode material for rechargeable lithium batteries. Our simulation models, basing lepidocrocite and 2-MnO2 type TiO2 were investigated by density functional theory （DFT）. The key issues are focused on the lithium insertion sites, electronic structures, and the conducting paths of Li＋ ions. Our calculated data indicate the calculated voltage of 2-MnO2 type TiO2 is higher than that of lepidocrocite type TiO2. The Li＋ ion migration energy barrier of lepidocroeite type YiO2 along the [1 0 0] direction （0.45 eV） is lower than that of along the [110] direction （0.57 eV）. The energy barriers of 2-MnO2 type TiO2 to move a Li＋ ion among the adjacent embedded sites （16c or 8a sites） is 0.68 eV.     

Orthorhombic 3-LiV2O5 as Cathode Materials in Lithium Ion Batteries： Synthesis and Property

The rod-like and bundle-like v-LiV205 were synthesized via a simple solvothermal process- ing. The rod-like 7-LiV205 with diameter of 500-800 nm and the bundle-like architectures are composed of several of order-attached rods with diameter of 100-600 nm. ＂y-LiV205 were synthesized using LiOH.H20, NH4VO3, HNO3, C2H5OH without and with PVP as raw materials. At the same time, the actual formation mechanism of Y-LiV205 was also investigated. As the cathode materials for lithium ion batteries, the bundle-like Y-LiV205 prepared with PVP delivers a better electrochemical performance, which has an initial dis charge capacity of 269.3 mAh/g at a current density of 30 mA/g and is still able to achieve 228 mAh/g after the 20th cycle. The good electrochemical properties of the as-synthesized Y-LiV205 coupled with the simple, relatively low temperature, and low cost of the prepara tion method may make this material a promising candidate as a cathode material for lithium ion batteries.     

Lithium storage properties of Ti3C2Tx (Tx = F,Cl, Br) MXenes

In this work, Ti₃C₂T_x MXene with -F, -Cl and -Br surface terminations are synthesized and the effect of these halogen terminations on the lithium storage properties is investigated. A maximum Li⁺ storage capacity of 189 mAh/g is achieved with Ti₃C₂Br_x MXene much higher than Ti₃C₂Cl_x and Ti₃C₂F_x with 138 mAh/g and 123 mAh/g, respectively. Density functional theory (DFT) calculation shows that the adsorption formation energy of halogen atoms on Ti atoms follows the trend of Ti-F > Ti-Cl > Ti-Br, leading to the same trend in the content of terminations on corresponding MXenes. In addition, inevitable exposure of MXene to oxygen causes competition between halogen and oxygen. Theoretical results show Ti₃C₂Br_x MXene has the highest Ti to O ratio and the lowest Ti to Br ratio, the high lithium affinity of O explains the maximum Li-ion storage capacity with Ti₃C₂Br_x MXene. This work shed light on the opportunity for achieving improved lithium storage properties of MXene electrodes by regulating the surface chemistry.     

XPS primary excitation spectra of Zn 2p,Fe 2p,and Ce 3d from ZnO, α-Fe2O3, and CeO2

Metal oxides are important for current development in nanotechnology. X-ray photoelectron spectroscopy(XPS) is a widely used technique to study the oxidation states of metals, and a basic understanding of the photoexcitation process is important to obtain the full information from XPS. We have studied core level excitations of Zn 2p, Fe 2p, and Ce 3d photoelectron emissions from ZnO, α-Fe₂O₃, and CeO₂. Using an effective energy-differential XPS inelastic-scattering cross section evaluated within the semiclassical dielectric response model for XPS, we analysed the experimental spectra to determine the corresponding primary excitation spectra, ie, the initial excitation processes. We find that simple emission (Zn 2p) as well as complex multiplet photoemission spectra (Fe 2p and Ce 3d) can be quantitatively analysed with our procedure. Moreover, for α-Fe₂O₃, it is possible to use the software package CTM4XAS (Charge Transfer Multiplet program for X-ray Absorption Spectroscopy) to calculate its primary excitation spectrum within a quantum mechanical model, and it was found to be in good agreement with the spectrum determined by analysis of the experiment.     

Synthesis,Structure Characterization and Optical Properties of β Lithium Zinc Phosphate

β-LiZnPO_4 single crystal was successfully synthesized via hydrothermal method. It crystallizes in the trigonal space group R3 with a = b = 13.6490 ?, c = 9.1123 ?, γ = 120.00° and Z = 18. Structure of the crystal is constructed by LiO_4, ZnO_4 and PO_4 tetrahedral units to form a three-dimensional(3 D) framework. The crystal has a high transmission ranging from 350 to 800 nm with UV cut-off edge at 220 nm. The nonlinear optical efficiency of the as-prepared β-LiZnPO_4 is about 1.2 times as large as that of KDP(KH_2PO_4) standard. Additionally, band structure and density of states calculations for β-LiZnPO_4 were performed using the total-energy code CASTEP, based on density functional theory(DFT).     

Molecular and Crystal Structure of 2, 3, 5, 6-dipropylene-r-pyrone

11NTRODUCT1ONWeattemptedtosynthesizeanextractant(1)bythereactionofadipylchloridewithcyclopentanonepiperidineenamineaccordingtoHunig'sprocedure"',however,wemainlyobtainedthetitlecompound,whichmaybepossiblyapotentialmedicinet2'3i.Itsmolecularstructurewasfinallyconfirmedbythesingle-crystalstructuredeterminationafterconventionalUV,IR,lHNMR,MSandelementana-lyticalworks.2EXPER1MENTALSECT1ON2.1SynthesisToastirredsolutioncontaining8Omlofchloroform,2.8mloftri-ethylamineand1.51g(O-Olmol)…     

Lithium–silicon Si n Li (n = 2–10) clusters and their anions: structures, thermochemistry, and electron affinities

The molecular structures, electron affinities, and dissociation energies of neutral Si _n Li (n = 2–10) species and their anions have been studied by the B3LYP and the BPW91 methods in conjunction with a DZP++ basis set. The geometries have been fully optimized with each of the proposed methods. The ground state structure of neutral Si _n Li keeps the corresponding Si _n framework unchanged. For anion, the corresponding Si _n (or ${{\rm Si}_{n}^{-}}$ ) framework changes largely when n ≥ 7. To evaluate the stability of the resulting anions we have calculated the adiabatic electron affinity (EA_ad), the vertical electron affinity (EA_vert), and the vertical detachment energy (VDE). The dissociating energies of Li from the lowest energy structures of neutral Si _n Li and their anions are calculated to examine relative stabilities.     

Lithium–sulfur redox: challenges and opportunities

Mechanistic and kinetic insights into the lithium–sulfur (Li–S) redox processes are essential to fundamentally increase the utilization of active material and further realize the practical applications of Li–S batteries. In this article, recent advances of in situ/operando characterizations of Li–S reaction processes and mechanism are presented, revealing the multistep transformations of S species. Interfacial visualization, from the whole interface to nanometer scale, provides specific evidence of sulfur distribution, polysulfide diffusion, and lithium sulfide precipitation. Moreover, the development of efficient electrocatalysts to improve the reaction kinetics are additionally presented and discussed. Although the understanding of the mechanism of the Li–S redox processes has improved in recent times, additional efforts are required for the scale-up production and practical applications of Li–S batteries.     

Curie and Pauli Spins in Lithium Intercalated MCMB

The lithium-intercalated carbon was originally a laboratory treasure of physicists, but it has now become the key material for the rechargeable lithium battery, which has the highest specific energy among all known chemical power sources. Although numerous techniques have been invoked to study the structure-property relationship of lithium-intercalated carbons, the problem has not been fully solved so far. There are only a few papers reporting ESR (electron spin resonance) studies of lithium …     

209Bi NQR in Mixed Oxides 2Bi2O3· B2O3, 3Bi2O3· 5B2O3, and Bi2O3· 3B2O3

It was earlier found from nuclear quadrupole resonance (NQR) measurements and computer modeling that -Bi₂O₃, Bi₃O₄Br and mixed oxides Bi₂O₃· 2Al₂O₃, Bi₂O₃· 2Ga₂O₃, Bi₂O₃· 3GeO₂, and 2Bi₂O₃· 3GeO₂exhibit local ordered magnetic fields from 30 to 200 G. It thus follows that these compounds are not diamagnets in a conventional sence of the word. With the aim of revealing previously unknown magnetic properties in bismuth(III) oxide-based Main Group element compounds, the mixed bismuth–boron oxides 2Bi₂O₃· B₂O₃, 3Bi₂O₃· 5B₂O₃, and Bi₂O₃· 3B₂O₃were prepared and studied using ²⁰⁹Bi NQR. The quadrupole interactions of the ²⁰⁹Bi nuclei and their electronic environment were studied, the crystallochemical features of the compounds were discussed, and the conformity of the ²⁰⁹Bi results to the X-ray structure data was verified. The preliminary tests in the field of a permanent magnet showed that the resonance intensities increase in external magnetic fields, indicating that a magnetism of unknown nature develops in the titled compounds. It was found reasonable to continue studies of the magnetic properties of these compounds using single-crystal ²⁰⁹Bi NQR in external magnetic fields.     

Infrared Isotopic Shift of Lithium Carbonate and Sulfate

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Geometric shielding corrections for calculation of electron scattering by CO2, C2H2, CHCl3, CH2Cl2, CH3Cl,CHF3, CH2F2 and CH3F at 30–5000 eV

Taking into account the changes of the geometric shielding effect in a molecule as the incident electron energy varies, an empirical fraction, which depends on the energy of the incident electrons, the target's molecular dimension and the atomic and electronic numbers in the molecule, is presented. Using this empirical fraction, a new formulation of the additivity rule is proposed. Using the new additivity rule, the total cross sections of electron scattering by CO₂, C₂H₂, CHCl₃, CH₂Cl₂, CH₃Cl, CHF₃, CH₂F₂ and CH₃F are calculated at the Hartree–Fork level at 30–5000 eV. The quantitative total cross sections are compared with those obtained by experiments and other theories, and good agreement is obtained over a wide energy range, especially above 100 eV.     

Diastereoselective Michael Addition of (4''''S)-Ethyl-3-(2'''',2''''-Dimethyl-1'''',3''''- dioxolan-4''''-yl) acrylate with Furyl Lithium

Recently we reported that the diastereoselective intramolecular [4+3] cycloaddition of 4 led to the formation of cycloadduct 5 as the only isolated isomer in 50% yield. The chiral C-3 of compound 4 could be used to direct the stereochemical course of [4+3] cycloaddition enabling the control of the relative stereochemistry between three contiguous asymmetric centers in adduct 51. The stereogenic center at C-3 of 4 was constructed by the asymmetric Michael addition of (, (-unsaturated ester 2 w…     

Conductance of Lithium and Sodium Perchlorates and Tetraphenylborates in 2-Butanone from −35 to 25°C

Conductances of dilute solutions of LiClO₄, NaClO₄, LiBPh₄ and NaBPh₄ in 2-butanone were measured at seven temperatures from ?35 to 25°C. The limiting molar conductivities and association constants were evaluated using the conductance equation of Fuoss and Justice (including the Chen effect). The distance parameter was fixed at the Bjerrum distance. The limiting ionic conductivities, determined by assuming equal ionic conductivities of the i-Am₃ BuN⁺ and BPh ₄ ^? ions at all temperatures, were related to the crystallographic ionic radii using the Hubbard–Onsager model of dielectric friction corrected for the inhomogeneity of the electric field. The activation enthalpy of ionic transport in 2-butanone is almost independent of the nature of the electrolyte. The Walden products do not vary with the temperature. The correction to the conductance parameters for dielectric saturation computed for M⁺ClO ₄ ^? associates was found to be small. Thermodynamic functions characterizing the association process were evaluated from K _A data and their dependences on the temperature. The short-range, noncoulombic contributions to the Gibbs energy were estimated using Bjerrum's theory.     

Syntheses,Crystal Structures,Visible, and Near-Infrared Luminescence Properties of 3d–4f Coordination Polymers Cu2Er2 and Eu2Ni2

Russian Journal of Coordination Chemistry - Solvothermal condition reaction of Ln(NO3)3 ? 6H2O (Ln = Er, Eu) with 5-nitroisophthalate (Nipt2–) and mononuclear macrocyclic oxamide...     

Complexes H2CO:PXH2 and HCO2H : PXH2 for X=NC,F, Cl,CN, OH,CCH, CH3, and H: Pnicogen Bonds and Hydrogen Bonds

Ab initio MP2/aug’-cc-pVTZ calculations have been carried out to investigate H₂CO : PXH₂ pnicogen-bonded complexes and HCO₂H : PXH₂ complexes that are stabilized by pnicogen bonds and hydrogen bonds, with X=NC, F, Cl, CN, OH, CCH, CH₃, and H. The binding energies of these complexes exhibit a second-order dependence on the O−P distance. DFT-SAPT binding energies correlate linearly with MP2 binding energies. The HCO₂H : PXH₂ complexes are stabilized by both a pnicogen bond and a hydrogen bond, resulting in greater binding energies for the HCO₂H : PXH₂ complexes compared to H₂CO : PXH₂. Neither the O−P distance across the pnicogen bond nor the O−P distance across the hydrogen bond correlates with the binding energies of these complexes. The nonlinearity of the hydrogen bonds suggests that they are relatively weak bonds, except for complexes in which the substituent X is either CH₃ or H. The pnicogen bond is the more important stabilizing interaction in the HCO₂H : PXH₂ complexes except when the substituent X is a more electropositive group. EOM-CCSD spin-spin coupling constants ^1pJ(O−P) across pnicogen bonds in H₂CO:PXH₂ and HCO₂H : PXH₂ complexes increase as the O−P distance decreases, and exhibit a second order dependence on that distance. There is no correlation between ^2hJ(O−P) and the O−P distance across the hydrogen bond in the HCO₂H : PXH₂ complexes. ^2hJ(O−P) coupling constants for complexes with X=CH₃ and H have much greater absolute values than anticipated from their O−P distances.     

Enzymatic Synthesis and Characterization of Novel Polycarbonates Derived from 5-Allyloxy-1, 3-dioxan-2-one and 5, 5-Dimethyl-1, 3-dioxan-2-one

Aliphatic polycarbonates and their copolymers have been used in drug controlled release system and other biomedical applications due to their good biocompatibility, favorable mechanical properties and some elasticity1, such as poly(1, 3-dioxan-2-one)2 and…     

Photoelectrochemical behavior,XPS and Auger of n-In_2S_3

n-In_2S_3 has been prepared by CVT method.The photoelectrochemical behavior of n-In_2S_3 in a polysulfide redox solution was investigated.It was found that photoetching remarkablyincreased the fill factor.The maximum quantum efficiency of carrier collection reached 95% after 12hirradiation at 100 mW/cm~2 at an applied potential of+1.2V.XPS and Auger analysis were carriedout for examining surface and bulk concentration.The photoetching effect could be satisfactorilyexplained.