[Bmim]FeCl_4离子液体的物理性质

研究了自制[Bmim]FeCl4离子液体的电导率、黏度与温度的关系,并与文献数据进行了对比.结果表明,采用落球法和旋转法都能准确地测量[Bmim]FeCl4离子液体的黏度;与Andrade方程相比,VTF方程能更好地拟合[Bmim]FeCl4离子液体的黏度和温度的关系,其相关系数达0.999 9.采用不同电导率仪测量的[Bmim]FeCl4离子液体的电导率有较大差别;相比Arrhenius方程而言,VTF方程能更好地拟合电导率与温度的关系;随着温度的变化,电导率与黏度的关系符合Walden规则,其相关系数达到0.99以上.     

离子液体[Cnpy][NTf2] (n=2, 4, 5)的动力粘度和电导率

在298.15-338.15 K和283.15-338.15 K温度范围内,分别测量了N-烷基吡啶双三氟甲磺酸亚胺(烷基链分别为:乙基、丁基、戊基)三种疏水型离子液体的动力粘度和电导率.利用Arrhenius 方程和Fulcher 方程将测量的动力粘度和电导率对温度拟合,得到了动力粘度和电导率随温度变化方程式.从电导率和密度计算出了上述三种离子液体在283.15-338.15 K温度范围内的摩尔电导率.应用Walden 规则,描述了动力粘度与摩尔电导率之间的关系.     

二元混合离子液体的电导率与离子间的缔合作用

在293.15-323.15 K范围内, 测定了13种常见离子液体及其25组混合体系的电导率. 利用Vogel-Tammann-Fulcher (VTF)方程对电导率数据进行拟合, 并通过方程式中的拟合参数分析了离子液体混合后其阴阳离子间缔合作用的变化规律. 结果表明,在相同温度下, 离子液体的阳离子侧链越短,阴离子电荷越分散, 阴阳离子间的氢键作用力越弱,离子液体的电导率越大, 其中阴离子的影响比阳离子更明显.混合离子液体中离子间的缔合作用不仅与阴阳离子的种类有关,而且与混合物的组成有关.     

Li2O～SiO2～RE2O3(RE=Y,La,Nd)体系的锂快离子导体

快离子导体的组成决定了它的性能, 为提高离子电导率可在硅酸锂体系快离子导体中加入稀土元素等第三组分. 运用混料均匀设计方法, 在Li2O～SiO2～RE2O3 (RE=Y, La, Nd)三元体系中, 设计了一系列均匀试验点, 用高温固相法合成了快离子导体. 继而通过对实验数据的多元回归分析, 以离子电导率为评价标准, 找出三元体系中离子电导率最好的区域, 其中选取的验证点的实测值与预测值相当. 这说明均匀设计法可用于快离子导体研究. 实验中所得的快离子导体室温电导率最高为LSLa: 1.15×10-6 S·cm-1.     

原位聚合制备的离子液体/聚合物电解质的研究

采用原位聚合制备出新型的BMIPF6/PMMA聚合物电解质透明弹性膜. 研究结果表明, BMIPF6/PMMA聚合物电解质体系在305 ℃时仍具有较好的热稳定性, 其安全性能优于含有机溶剂的传统非水电解质体系. 随着离子液体含量的增加, 其玻璃化转变温度逐渐减小, 离子电导率升高; 且离子电导率与温度的关系服从VTF方程. 其中, 当BMIPF6的质量分数为50%时, 该聚合物电解质的室温离子电导率高达0.15 mS/cm.     

红外光谱研究PEO基离子液体聚合物电解质

以聚氧化乙烯(PEO)为聚合物基体, 双三氟甲基磺酸亚酰胺锂(LiTFSI)为锂盐, 加入不同量的离子液体(BMIMPF₆)为增塑剂, 制备离子液体聚合物电解质. 运用发射FTIR光谱技术实时监测所制备聚合物电解质的结构随温度的变化. 结合FTIR透射光谱\, SEM和XRD的研究结果分析了离子液体对离子电导率的影响, 并初步提出离子导电增强机制.     

B_2S_3-Li_2S-LiI玻璃态离子电导率

B_2S_3-Li_2S-LiI 体系玻璃态在常温下锂离子电导率高达1.7×10~(-3)(?)~(-1)cm~(?),它是一种很有希望的二次锂电池的固体电解质。本文作者成功地制备出这类玻璃,并对影响离子电导率的因素进行了研究。     

新型复合聚合物电解质离子导电行为的研究

PEG600和CH₂Cl₂通过Williamson缩聚反应,生成主链柔顺的PEG共聚物.¹H NMR测试表明其以[CH₂O(CH_2>CH₂O)¹³]为重复结构单元.与聚合物质量含量8%的气相SiO₂及适量的LiN(CF₃SO₂)2掺杂,制备一系列新型复合聚合物电解质.通过AC阻抗研究离子电导率,提出适合本体系的等效电路.该体系具有良好的成膜性能与热稳定性能,电导率比传统的PEO/盐体系高2～3个数量级.离子电导率随着温度的升高而增加,低温电导率增加较快,高温电导率增加较慢,呈非Arrhenius变化.在EO/Li=13～34:1(摩尔比)范围内,离子电导率随着盐浓度的变化出现两个峰值,低盐浓度的峰值较高.在303 K, EO/Li=28:1时,最大离子电导率接近10^-4 S/cm.     

两种疏水型膦类离子液体的密度、动力粘度及电导率（英文）

通过传统的方法,制备了两种对水和空气稳定的四烷基膦类离子液体。离子液体是:己基三丁基膦四氟化硼和己基三丁基膦双三氟甲基磺酸亚胺。在T=283.15-353.15 K温度范围内,测定了两个离子液体的密度、动力粘度及电导率。讨论了温度、阴离子结构对离子液体的性质的影响。结合文献报道的其它离子液体,讨论了该类离子液体性质随阳离子结构的变化规律,并与咪唑类离子液体的性质进行了比较。通过经验方程,利用密度数据计算了两个离子液体的重要热力学性质参数,例如:分子体积、标准摩尔熵及晶格能等。并将估算性质与传统的咪唑、吡啶类离子液体进行了对比。通过密度和电导率确定了离子液体的摩尔电导率。讨论了Vogel-Fulcher-Tamman(VFT)方程和Arrhenius方程对于粘度和电导率拟合的可行性,并估算了电导活化能及流动活化能。通过Walden规则,描述了密度、粘度及电导率之间的联系。有关研究对新型离子液体的合成及其工业化的应用具有十分重要意义。     

质子型离子液体N,N-二甲基乙醇胺丙酸盐的密度、粘度及电导率

在283.15-333.15 K温度范围内, 测量了质子型离子液体N,N-二甲基乙醇胺丙酸盐(DMEOAP)的密度、粘度及电导率. 讨论了温度对密度、粘度和电导率等物理化学参数的影响. 通过经验和半经验方程得到了该离子液体的热膨胀系数、分子体积、标准摩尔熵及晶格能等热力学性质参数. 由电导率和密度计算出了该离子液体的摩尔电导率. 利用Vogel-Fulcher-Tamman (VFT)方程, 将测量的动力粘度和电导率对温度拟合, 得到了动力粘度和电导率随温度变化方程式.并通过Walden规则, 建立了粘度与摩尔电导率之间的联系.     

First-principles calculation of the 17O NMR parameters of a calcium aluminosilicate glass

We have computed the (17)O NMR parameters of an amorphous calcium aluminosilicate (CAS) from first-principles. The atomic coordinates of a CAS glass of composition (CaO)(0.21)(Al(2)O (3))(0.12)(SiO (2))(0.67) were obtained by quenching a liquid to room temperature by the means of ab initio molecular-dynamics simulations of the Car-Parrinello type. The structure of the glass is found to be overall in good agreement with diffraction experiments. Some excess nonbridging O (NBO) atoms are found and are compensated by tricluster O atoms, i.e., by 3-fold coordinated O atoms to 4-fold coordinated Al or Si atoms. The glass coordinates were used to compute the (17)O NMR parameters using GGA-DFT and a correction of the Ca 3d orbital energy. The chemical shifts and the electric field gradients were obtained with the gauge including projector augmented-wave (GIPAW) and the projector augmented-wave (PAW) methods, respectively. The simulated 2D-3QMAS NMR spectrum of the CAS glass is in very good agreement with the available experimental data, notably because it takes into account the disorder present in the glass. This agreement further validates our CAS glass model. We show that the oxygen triclusters are not visible in a 2D-3QMAS NMR (17)O spectrum since their NMR parameters overlap with those of the Al-O-Si, Si-O-Si, or Al-O-Al sites. Finally, correlations between the structural characteristics and the values of the NMR parameters are extracted from the calculation with the aim of helping the interpretation of NMR spectra of glasses of similar compositions.     

Electrical Properties of Polycrystalline Lithium Chloroboracite Prepared by the Sol-Gel Method

The electrical properties of polycrystalline lithium chloroboracite, Li4B7O12Cl, prepared by the sol-gel method were investigated in connection with their structure. Li4B7O12Cl pellets were prepared with different amounts of hydrochloric acid or ammonium chloride. The kind and amount of the chlorine source affected the formation of by-products (Li2B4O7, LiCl, a glass phase) and the morphology of the Li4B7O12Cl pellets. Thus their conductivity, which is dominated by grain boundary response owing to the high porosity of the materials, was also affected. The formation of Li2B4O7 as a by-product led to a higher activation energy and lower conductivity. In those pellets in which Li2B4O7 did form, an increase of the amount of glass phase led to higher conductivities.     

Semi-ideal solution theory. 2. Extension to conductivity of mixed electrolyte solutions

Conductivities were measured for the ternary systems NaCl-LaCl(3)-H(2)O and KCl-CdCl(2)-H(2)O and their binary subsystems NaCl-H(2)O, KCl-H(2)O, CdCl(2)-H(2)O, and LaCl(3)-H(2)O at 298.15 K. The semi-ideal solution theory for thermodynamic properties of aqueous solutions of electrolyte mixtures was used together with the Eyring absolute rate theory to study conductivity of mixed electrolyte solutions. A novel simple equation for prediction of the conductivity of mixed electrolyte solutions in terms of the data of their binary solutions was established. The measured conductivities and those reported in literature were used to test the newly established equation and the generalized Young's rule for conductivity of mixed electrolyte solutions. The comparison results show that the deviation of a ternary solution from the new conductivity equation is closely related to its isopiestic behavior and that the deviations are often within experimental uncertainty if the examined system obeys the linear isopiestic relation. While larger deviations are found in the system with large ion pairing effect, the predictions can be considerably improved by using the parameters calculated from its isopiestic results. These results imply that the previous formulation of the thermodynamic properties of aqueous solutions of electrolyte mixtures has a counterpart for transport properties.     

Conductivities of KF and CsF in methanol at 25°C

Electrolytic conductivities of KF and CsF in methanol solution have been determined at 25°C. The single ion molar conductivities of the fluoride ion, obtained from the two salts are in excellent agreement and indicate that the F^? ion is highly solvated in methanol (MeOH). Combination of the present and literature data for related salts in both water and MeOH indicate that while the primary solvation of ions may be more extensive in H₂O there is considerable enhancement of the secondary solvation sheath in MeOH. Recalculation of high precision literature conductivity data using a consistent mathematical approach indicates that ion pair formation constants for simple 1:1 electrolytes in MeOH are 1 or 2 orders of magnitude greater than in H₂O. This is shown to be entirely due to the less favorable solvation of ions in MeOH, as the Gibbs energies of transfer of the neutral ion pairs MX from H₂O to MeOH are also unfavorable. Calculations also show that ion association in MeOH is strongly influenced by coulombic interactions whereas in H₂O short range interactions are generally more important.     

Structures and vibrations of Nb3O and Nb3O-: a density functional study

Density functional calculations of neutral and anionic niobium trimer monoxides are presented. The calculations were performed employing scalar quasirelativistic effective core potentials. In order to test the accuracy of the used effective core potentials in the framework of density functional theory the pulsed field ionization-zero electron kinetic energy photoelectron spectrum of Nb(3)O was simulated and compared to experiment. Different isomers of Nb(3)O and Nb(3)O(-) were studied in order to determine the ground state structures. For both neutral and anionic systems a planar C(2v) structure with an edge-bound oxygen atom was found as a ground state. Equilibrium structure parameters, harmonic frequencies, and adiabatic electron affinity are reported. The calculated electron affinity and frequencies are in good agreement with the available experimental data obtained recently from vibrationally resolved negative ion photoelectron spectroscopy.     

Structural, optical, physical and electrical properties of V2O5.SrO.B2O3 glasses

The present work aims to study the structure and variation of optical band gap, density and dc electrical conductivity in vanadium strontium borate glasses. The glass systems xV2O5.(40-x)SrO.60B2O3 and xV2O5.(60-x)B2O3.40SrO with x varying from 0 to 20 mol% were prepared by normal melt quench technique. Structural studies were made by recording IR transmission spectra. The fundamental absorption edge for all the glasses was analyzed in terms of the theory proposed by Davis and Mott. The position of absorption edge and hence the value of the optical band gap was found to depend on the semiconducting glass composition. The absorption in these glasses is believed to be associated with indirect transitions. The origin of Urbach energy is associated with the phonon-assisted indirect transitions. The change in both density and molar volume was discussed in terms of the structural modifications that take place in the glass matrix on addition of V2O5. dc conductivity of the glass systems is also reported. The change of conductivity and activation energy with composition indicates that the conduction process varies from ionic to polaronic one.     

Density functional calculations of ATP systems. 1. Crystalline ATP hydrates and related molecules

Adenosine 5'-triphosphate (ATP) is an essential energy carrier in mammalian and other cells, and its hydrolysis to the diphosphate (ADP) in the presence of metal cations (e.g., Mg(2+) or Ca(2+)) is one of the most prevalent biochemical reactions. We describe here density functional (DF) calculations on closely related systems and compare the results with other calculations and available experimental data: Na(H2O)n +, Mg(H2O)n 2+, and Ca(H2O)n 2+ clusters (n = 1, 4-7), the crystalline pyrophosphates Mg(2)P(2)O(7).6H2O and alpha-CaNa(2)P(2)O(7).4H2O, and crystalline Na(2)ATP.3H2O. The last of these comprises asymmetric units of ATP dimers (monomers A and B) in a double-protonated state H(2)(ATP)(2-). The calculated structures agree well with available measurements and provide additional information, including the location of the H atoms. Analysis of the dipole moments of individual ATP monomers and their dimers shows that the crystal comprises blocks of opposing dipoles. Replacing one Na+ ion with Mg2+ or Ca2+ results in a significant elongation of the terminal bridging P-O bond. The calculations provide benchmarks for the use of DF methods in ATP systems and are used in the companion paper to study the hydrolysis of ATP at the active site of the protein actin.     

Modelling a P-FAIMS with multiphysics FEM

A micro Planar high-Field Asymmetric waveform Ion Mobility Spectrometer (P-FAIMS) operating at ambient pressure and temperature has been simulated using COMSOL Multiphysics software. P-FAIMS is based on ion gas-phase separation due to the dependence of ion mobility with electric field. Ions are selected by a DC voltage characteristic of each ion kind. Physics of ion behaviour in high electric fields conditions is well known but not the chemistry behind ion reactions and kinetics. The aim of this work is the modelling of different kind of ions in a P-FAIMS having account of the main factors involved in their movement in the drift tube. Simulations of vapour phase ions of three compounds have been studied for different values of drift electric field amplitude to gas number density (E/N) ratio: protonated water clusters H⁺(H₂O) _n and O₂^-(H₂O)_n{{\rm O}_{2}^{-}({\rm H}_{2}{\rm O})_{n}} ions obtained in air, and a chemical warfare agent simulant DMMPH⁺ that emulates gas sarin. Ions were selected due to simulation needs of experimental data of the main quantities involved in the definition of ions mobilities. Results show that simulations of ions behaviour in a P-FAIMS are possible with COMSOL Multiphysics software and that the time and intensity at which ions are detected are in good agreement with experimental data from literature.     

A molecular dynamics simulation of the electrical conductivity behaviors of highly concentrated liquid ammoniates NaIalphaNH(3): comparison with experimental measurements

In this paper, we present a molecular dynamics simulation study devoted to the calculation of the electrical conductivities of highly concentrated liquid electrolytes as a function of their dilution. As an illustration, we give the first such study of the ammoniate NaIalphaNH(3). The theoretical results are presented together with experimental data obtained at 293 K, and show that the calculated conductivities are in agreement with the experimental values in the whole salt dilution range provided that correlations between the species in the solution are taken into account. Indeed, the usual Nernst-Einstein relation is a crude approximation to calculate accurately the conductivities in such high concentrated electrolytes.     

Proline zwitterion dynamics in solution, glass, and crystalline state

Raman and Raman optical activity spectra of L- and D-proline zwitterionic (PROZW) forms were recorded for H(2)O and D(2)O solutions in a wide frequency range and analyzed with respect to the motion of the proline ring and rotation of the carbonyl group. The solution spectra were additionally compared to Raman scattering of glass and crystalline powder proline. Solution and glass spectral band broadenings are similar and reveal information about the extent of internal molecular motion. Two distinct but equally populated flexible forms were found in the glass and the solution. The equal population is consistent with NMR data, temperature, and concentration dependencies. The molecular flexibility is reduced significantly in the crystal, however, where only one conformer is present. Consequently, the crystal bands are narrow and exhibit minor frequency shifts. The spectra were interpreted with the aid of density functional theory computations involving both continuum and explicit solvent. A two-dimensional potential energy surface pertaining to the five-member ring puckering coordinates was constructed and used for dynamical averaging of spectral properties. Comparison of the computed and experimental bandwidths suggests that the puckering is strongly correlated with the carbonyl rotation. An averaging over these two motions produces similar results. The interpretation of the Raman experiments with the aid of the simulation techniques also indicates that the environment modulates properties of the hydrophobic part of the molecule indirectly by interacting with the ionic group. Such behavior may be important for the reactivity and biological activity of proline-containing peptides and proteins.