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1.
Increases in photovoltaic performances for dye-sensitized solar cells having ionic liquid type electrolytes are reported. These results are explained by diffusion coefficient for I3, charge transfer resistances on counter electrodes, flat band potentials of TiO2, redox potentials for I/I3, electron diffusion constants, electron life time, and diffusion length in TiO2 layers. Methylpropylimidazolium iodide is selected because of the lowest viscosity and the highest conductivity. Increases in the photovoltaic performance are observed when a small amount of water was added into the ionic liquid consisting of both LiI and t-butylpyridine as the additives. These improvements are brought about by enhancements of all of Jsc, ff and Voc. The increases in Jsc and ff are associated with the decrease in charge transfer resistances on counter electrodes and increases in ionic conductivities. Voc may be explained by an increase in the difference between redox potentials of I/I3 and Fermi level.  相似文献   

2.
In recent years, there has been considerable interest in predicting the crystal densities of both molecular and ionic energetic compounds using the computed volumes Vm of the isolated gas phase molecules or ions. The surfaces enclosing the volumes are taken to be the 0.001 au (electrons/bohr3) contours of the molecules’ and ions’ electronic densities. For molecular solids, it is known that the ratio M/Vm (M = molecular mass) gives densities that are overall reasonably good, although they can be markedly improved by introduction of an electrostatic interaction correction term. For ionic solids, the subject of this paper, the ratio M/Vm (M = formula unit mass) is not nearly as effective; Vm tends to be significantly larger than the effective volumes of the ions in the crystal, leading to underestimated densities, with an average absolute error of 0.089 g/cm3. The correction term that improves molecular crystal densities is not applicable in the case of ionic solids; however we show, for a database of 25 compounds plus five test cases, that an average absolute error of 0.033 g/cm3 can be achieved by combining M/Vm with terms involving the average positive and negative potentials and areas on the cationic and anionic surfaces. The root-mean-square error is 0.040 g/cm3.  相似文献   

3.
The optical absorption spectrum of Ni2+ ion doped in lecontite (sodium ammonium sulphate dihydrate) single crystal has been studied at room and liquid air temperatures. All the bands could be assigned assumingO h symmetry for the Ni2+ ion in the crystal. The splitting of3 T 1g (F) band at liquid air temperature has been attributed to spin-orbit interaction. The crystal field and spin-orbit parameters derived areD q=1000 cm?1;B=740 cm?1;C/B=4.27 and ζ=600 cm?1. All the bands observed show a blue shift when the crystal was cooled to liquid air temperature.  相似文献   

4.
The newly prepared ionic liquid, 1-butyl-3-methylimidazolium benzoate, ([bmim][BA]), was found to enhance the fluorescence of Eu3+ and Tb3+. The fluorescence enhancement resulted from a sensitization of the lanthanide fluorescence by the benzoate anion of the ionic liquid, [bmim][BA], and a reduction in the non-radiative channels in the non-aqueous environment provided by the ionic liquid. However, the fluorescence enhancement of the lanthanides in the ionic liquid was limited due to the operation of the inner filter effect, which resulted from the strong absorption of the benzoate. The inner filter effect was minimized by observing the Eu3+ fluorescence using a front face geometry and also by diluting the lanthanide-[bmim][BA] system, using another ionic liquid, 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([bmim][Tf2N]), as a solvent. In the case of Tb3+, the emission from the lanthanide was masked by the strong emission from the ionic liquid in the region 450-580 nm. The long lived Tb3+ emission was therefore observed using delayed gated detection, where an appropriate delay was used to discriminate against the short lived emission from the ionic liquid. The large fluorescence enhancement due to ligand sensitized fluorescence observed with [bmim][BA] diluted in [bmim][Tf2N], leads to nanomolar detection of the lanthanides. This is, to the best of our knowledge, the first report of an ionic liquid being employed for ligand sensitized fluorescence enhancement of lanthanides.  相似文献   

5.
Glassy solid electrolytes were prepared by combining the 50Li2SO4·50Li3BO3 (mol%) ionic glass and the 1-ethyl-3-methyl-imidazolium tetrafluoroborate ([EMI]BF4) ionic liquid. High-energy ball milling was carried out for the mixture of the inorganic ionic glass and the organic ionic liquid. The ambient temperature conductivity of the glass electrolyte with 10 mol% [EMI]BF4 was 10−4 S cm−1, which was three orders of magnitude higher than that of the 50Li2SO4·50Li3BO3 glass. The addition of [EMI]BF4 to the ionic glass decreased glass transition temperature (Tg) of the glass and the decrease of Tg is closely related to the enhancement of conductivity of the glass. Morphology and local structure of the glass electrolyte was characterized. The dissolution of an ionic liquid in an ionic glass with Li+ ion conductivity is a novel way to developing glass electrolytes for all-solid-state lithium secondary batteries.  相似文献   

6.
Ultrasound (US) effect on 1-butyl-3-methyl-imidazolium (BMI) ionic liquids having different counter anions, BF4, PF6 and Cl in aqueous medium was studied by FT-IR spectroscopy. Their deconvolution spectra were used to analyze the change of hydrogen bond in the absence and presence of US exposure to the ionic liquid. The FT-IR spectra were measured in different water contents without and with US at 23 kHz. These results indicated that the counter anion species in the imidazole based the ionic liquids played an important role for water solvation, when the US was exposed. The US hardly changed hydrogen bonding in the aqueous BMI–PF6, while the BMI–BF4 and BMI–Cl showed obvious change in their FT-IR spectra. Especially for the BMI–Cl, significant change was observed by the US exposure in the range of 2.6 wt% to 20 wt% of water contents. The results showed that the US could break the hydrogen bond in the BMI–Cl ionic liquids. In the case of BMI–BF4, the FT-IR band at 950–1152 cm−1 was significantly intensified under US exposure, due to that the US influenced BF4-water interaction. But, it was observed that the ionic liquid having PF6 was very less changed in the US system.  相似文献   

7.
The ionic and electronic conductivities of the lithium nitride bromides Li6NBr3 and Li1 3N4Br have been studied in the temperature range from 50 to 220°C and 120 to 450°C, respectively. Both compounds are practically pure lithium ion conductors with negligible electronic contribution. Li6NBr3 has an ionic conductivity Ω of 2 × 10-6Ω-1cm-1 at 100°C and an activation enthalpy for σT of 0.46 eV. Li1 3N4Br shows a phase transition at about 230°C. The activation enthalpy for σT is 0.73 eV below and 0.47 eV above this temperature. The conductivities at 150 and 300°C were found to be 3.5 × 10-6 Ω-1cm-1 and 1.4 × 10-3Ω-1cm-1, respectively. The crystal structure is hexagonal at room temperature with a = 7.415 (1)A? and c = 3.865 (1)A?.  相似文献   

8.
Inorganic–organic hybrid membranes were prepared by sol–gel process with tetramethoxysilane/methyltrimethoxysilane/diisopropyl phosphite and 1-butyl-3-methylimidazolium tetrafluoroborate (BMIMBF4) ionic liquid as precursors. The Fourier transform infrared spectroscopy (FT-IR) and 31P, 29Si, 1H, 13C, and 19F nuclear magnetic resonance measurements have shown good chemical stability and complexation of (POH[(CH3)2CHO]2) with [BMIMBF4] ionic liquid in the fabricated hybrid membranes. The influence of the textural properties of all the prepared composite membranes could be interpreted from nitrogen adsorption–desorption measurements. The average pore size was increased proportionally with the ionic liquid weight percent ratio in the host phosphosilicate matrix from 2.59 to 11.71 nm, respectively. Thermogravimetric analysis and differential thermal analysis measurements confirmed that the hybrid membranes were thermally stable up to 260 °C. Thermal stability of the hybrid membranes was significantly enhanced by the presence of inorganic SiO2 framework and high stability of [BF4] anion. For all the composite membranes, the conductivities were measured within the temperature range (−30 °C) to 150 °C, and a maximum conductivity of 7 × 10−3 S/cm at 150 °C was achieved for 40 wt.% ionic liquid-based composite membrane under nonhumidified conditions.  相似文献   

9.
The optical activity of trigonal coordination compounds is investigated using the crystal field theory. The ionic model is shown to account for the circular dichroism of Co(en)3 +3. The absolute configuration of Cr(C2O4)3 -3 is assigned on the basis of the ionic model.  相似文献   

10.
A new relativistic approach to the problem of constructing effective local hadron-hadron potentials is proposed on the basis of analytic S-matrix theory and Gelfand-Levitan-Marchenko-Martin methods for solving the inverse quantum scattering problem. An effective potential is defined as a local operator in a partial-wave equation of the quasipotential type such that it generates an on-shell relativistic (Feynman) scattering amplitude that has required discontinuities at dynamical cuts. The method is used to construct nucleon-nucleon potentials in the 1 S 0-and 3 S 1-wave states. The dynamical discontinuities of partial-wave amplitudes for nucleon-nucleon scattering are calculated on the basis of the one-bosonexchange model that takes into account the exchanges of π, σ, ρ, ω, η, and α 0 mesons. It is shown that the nonlinear relation between the discontinuities of partial-wave scattering amplitudes at dynamical cuts and interaction operators generates additional short-range repulsion not associated with omega-meson exchange. The experimental energy dependences of phase shifts in the channels of nucleon-nucleon scattering that are considered here are faithfully reproduced by the results of the calculations up to the projectile-nucleon kinetic energies in the range T = 1.5–2.0 GeV.  相似文献   

11.
Intramolecular electron spin exchange (IESE) in two nitroxide biradicals, R6–C≡C–C≡C–R6 (1) and R6–C≡C–p-C6H4–C≡C–R6 (2), is studied as a function of temperature and solvent properties. The effect of molecular solvents and ionic liquids (ILs, [1-methyl-3-butylimidazolium]+[PF6]?, bmimPF6, and [1-methyl-3-octylimidazolium]+[BF4]?, omimBF4) on the IESE in magnetically diluted solutions is investigated. Changes in electron paramagnetic resonance spectra are analyzed and the thermodynamic parameters of these changes are calculated. Geometry optimization and D-tensor calculations of biradicals 1 and 2 were carried out on the DFT/UB3LYP/cc-pVdz and DFT/ROPBE/N07D levels of theory. The probable differences in biradical behavior are discussed.  相似文献   

12.
Lithium ion conducting solid-state composites consisting of lithium ion conducting ionic liquid, lithium bis(trifluoromethanesulfonyl)amide (Li-TFSA) dissolved 1-ethyl-3-methyl imidazolium bis(trifluoromethylsulfonyl)amide (EMI-TFSA), denoted by [yMLi+][EMI+][TFSA] in this study, and various oxide particles such as SiO2, Al2O3, TiO2 (anatase and rutile) and 3YSZ are synthesized via a liquid route for the molar concentration of lithium, y, to be 1. The composite consists of SiO2 and the ionic liquid with y = 0.2 was also prepared. The ionic liquid are quasi-solidified at the above oxide particle surfaces when x is below 40 for y = 1 and x is below 30 for y = 0.2, corresponding to the confinable thickness of the ionic liquid at the oxides' surfaces to be approximately 5-10 nm regardless of the oxide compositions. The electrical conductivities of x vol.%[yMLi+][EMI+][TFSA-]-SiO2, Al2O3, TiO2s or 3YSZ composites are evaluated by ac impedance measurements. The quasi-solid-state composites exhibited liquid-like high apparent conductivity, e.g. 10− 3.3-10− 2.0 S cm− 1 in the temperature range of 323-538 K for SiO2-ionic liquid composites with y = 1. The self-diffusion coefficients of the constituent species of x vol.% [yMLi+][EMI+][TFSA] (x is below 40, y = 0.2 and 1) − SiO2 are evaluated by the Pulse Gradient Spin Echo (PGSE)-NMR technique in the temperature range of 298-348 K. By the quasi-solidification of the ionic liquid at SiO2 particle surfaces, the absolute values of the diffusion coefficients of all constituent species decreased. The SiO2 surfaces work to promote ionization of ion pair, [EMI+][TFSA], while significant influence on the solvation coordination, [Li(TFSA)n + 1]n, was not observed. The apparent transport numbers of Li-containing species both in the bulk and the quasi-solidified ionic liquid showed similar values with each other, which was evaluated to be in the range of 0.010-0.017 for y = 0.2 and 0.051-0.093 for y = 1 in the abovementioned temperature range.  相似文献   

13.
Biodegradable solid polymer electrolyte (SPE) is prepared by solution-casting technique using low-cost cellulose derivative, hydroxypropylmethyl cellulose (HPMC) as a host polymer. Owing to the hydrophobic nature of this polymer, it is predicted to exhibit low ionic conductivity upon addition of magnesium trifluoromethanesulfonate (MgTf2) salt. Therefore, ionic liquid (IL), 1-butyl-3-methylimidazolium trifluoromethanesulfonate (BMIMTf), is added in order to enhance its ionic conductivity. Based on the findings, the ionic conductivity at room temperature and the dielectric behaviors of the SPE complex improved upon incorporation of 40 wt.% IL. On top of that, addition of IL reduces the degree of crystallinity and the glass transition temperature (T g ) of the SPE. The conductivity-temperature plot revealed that the transportation of ions in these films obey Arrhenius theory. The interaction between SPE complex, MgTf2 salt, and BMIMTf is investigated by means of Fourier transform infrared (FTIR) spectroscopy through the change in peak intensity around 3413, 1570, and 1060 cm?1, which are responsible for –OH stretching band, C–C and C–N bending modes of cyclic BMIM+, and C–O–C stretching band, respectively.  相似文献   

14.
Recent work by others has shown that the densities of C,H,N,O molecular crystals are, in many instances, given quite well by the formula M/Vm, in which M is the molecular mass and Vm is the volume of the isolated gas phase molecule that is enclosed by the 0.001 au contour of its electronic density. About 41% of the predictions were in error by less than 0.030 g/cm3, and 63% by less than 0.050 g/cm3. However, this leaves more than one-third of the compounds with errors greater than 0.050 g/cm3, or in some instances, 0.100 g/cm3. This may indicate that intermolecular interactions within the crystal are not being adequately taken into account in these cases. Accordingly, the effectiveness of including a second term that reflects the strengths, variabilities and degree of balance of the positive and negative electrostatic potentials computed on the surfaces of the isolated molecules, has been included. The database was selected such that half of the densities predicted by M/Vm had errors larger than 0.050 g/cm3. The introduction of the electrostatic interaction correction produced a marked improvement. Overall, 78% of the predictions are within 0.050 g/cm3 of experiment, with 50% within 0.030 g/cm3. Among those that originally all had errors larger than 0.050 g/cm3, 67% are now less. The reasons for the better performance of the dual-variable formula are analysed.  相似文献   

15.
Nanocomposite polymer electrolyte thin films of polyvinyl alcohol (PVA)-orthophosphoric acid (H3PO4)-Al2O3 have been prepared by solution cast technique. Films are irradiated with 50 MeV Li3+ ions having four different fluences viz. 5?×?1010, 1?×?1011, 5?×?1011, and 1?×?1012 ions/cm2. The effect of irradiation on polymeric samples has been studied and characterized. X-ray diffraction spectra reveal that percent degree of crystallinity of samples decrease with ion fluences. Glass transition and melting temperatures have been also decreased as observed in differential scanning calorimetry. A possible complexation/interaction has been shown by Fourier transform infrared spectroscopy. Temperature-dependent ionic conductivity shows an Arrhenius behavior before and after glass transition temperature. It is observed that ionic conductivity increases with ion fluences and after a critical fluence, it starts to decrease. Maximum ionic conductivity of ~2.3?×?10?5 S/cm owing to minimum activation energy of ~0.012 eV has been observed for irradiated electrolyte sample at fluence of 5?×?1011 ions/cm2. The dielectric constant and dielectric loss also increase with ion fluences while they decrease with frequency. Transference number of ions shows that the samples are of purely ionic in nature before and after ion irradiation.  相似文献   

16.
Attenuated total reflectance–Fourier transformed infrared spectroscopy measurement is employed to study the interactions between the components of 30% methyl-grafted natural rubber (MG30), lithium trifluromethanesulfonate (LiCF3SO3 or LiTF), and propylene carbonate (PC). Vibrational spectra data of LiTF reveals that the νs(SO3) at 1,045 cm−1, δs(CF3) at 777 cm−1, and C=O stretching mode at 1,728 cm−1 for MG30 have shifted to lower wave numbers in MG30–LiTF complexes indicating that complexation has occurred between MG30 and LiTF. The solvation of lithium ion is manifested in Li+ ← O=C interaction as shown by the downshifting and upshifting of C=O mode at 1,788 to 1,775 cm−1 and νas(SO3) at 1,250 to 1258 cm−1, respectively, in LiTF–PC electrolytes. There is no experimental evidence of the interaction between MG30 and PC. Competition between MG30 and PC on associating with lithium ion is studied, and the studies show that the interaction between MG30–LiTF is stronger than that of the PC–LiTF in plasticized polymer–salt complexes. The effect of PC on the ionic conductivity of the MG30–LiTF system is explained in terms of the polymer, plasticizer, and salt interactions. The temperature dependence of conductivity of the polymer films obeys the Vogel–Tamman–Fulcher relation. Values of conductivity and activation energy of the MG30-based polymer electrolyte systems are presented and discussed.  相似文献   

17.
The polyethylene oxide (PEO) based lithium ion conducting polymer electrolytes complexed with lithium trifluoromethanesulfonate (LiCF3SO3 or LiTf) plasticized with an ionic liquid 1-ethyl 3-methyl imidazolium trifluoromethanesulfonate (EMITf) have been reported. Morphological, spectroscopic, thermal and electrochemical investigations demonstrate promising characteristics of the polymer films, suitable as electrolyte in various energy storage/conversion devices. Significant structural changes have been observed in the polymer electrolyte due to the ionic liquid addition, investigated by X-ray diffraction (XRD) and optical microscopy. The ion-polymer interaction, particularly the interaction of imidazolium cation with PEO chains, has been evidenced by IR and Raman spectroscopic studies. The optimized composition of the polymer electrolyte i.e. PEO25.LiTf + 40 wt.% EMITf offer room temperature ionic conductivity of ~ 3 × 10− 4 S cm− 1 with wide electrochemical stability window and excellent thermal stability. The ‘σ versus 1/T’ curves show apparent Arrhenius behavior below and above melting temperature. The ionic conductivity has been observed due to Li+ ions, as confirmed from 7Li-NMR studies, though the component ions of ionic liquid and anions also contribute significantly to the overall conductivity.  相似文献   

18.
We have measured the nuclear spin lattice relaxation time in liquid indium from 130°C to 300°C to be: 1/T 1=(1.98 × 0.0082T) × 103 sec-1. The relaxation rate consists of two significant parts: (1/T 1) K from the nuclear magnetic hyperfine interaction, and (1/T 1) Q from the nuclear quadrupole interaction. We calculate (1/T 1) K from the the modified Korringa relation using a correction factor of order unity for electron-electron interactions. The hyperfine term is linear in T and accounts for the second term in 1/T 1. Within experimental error the remaining rate, (1/T 1) Q , is temperature independent, and theoretically varies as the product of the square of the electric field gradient, q, and τc, a typical time between field gradient fluctuations. Making use of the x-ray RDF, we construct a simple model for liquid indium and calculate the ionic and electronic contributions, q I and q E, to the electric field gradient, to be q I=1.4 × 1024/cm3 and q E=8.5 × 1024/cm3. The calculation of q E assumes covalent bonding between nearest neighbours. Taking q I and q E to be of opposite sign, we find that the correlation time τc is 1.6 × 10-13 sec. When we further identify τ c with the correlation time for diffusion in a three-dimensional random walk, we are able to calculate the r.m.s. jump distance, Δr D, involved in self-diffusion, Δr D=0.38 Å. This value is consistent with the x-ray peak width of 0.38 Å which we used earlier to calculate the electric field gradient.  相似文献   

19.
The susceptibility of dilute Co impurities in liquid Sn is reported. It displays an almost linear increase from 1.8 × 10?4 cm3/mole at 240°C to 4.5 × 10?4 cm3/mole at 1000°C. These results are compared with other experimental information and are shown to be consistent with a recently proposed ionic impurity model if an interaction parameter is assumed to be temperature dependent.  相似文献   

20.
The phenomenological crystal-field potentials of cubic and trigonal Yb3+ centers in a CsCaF3 crystal have been determined from the experimental energy-level schemes. These potentials are compared with the potentials of the analogous centers in the isomorphic hosts KMgF3 and KZnF3. Information about the phonon spectrum of a CsCaF3:Yb crystal was obtained from the electronic-vibrational structure of the luminescence spectra. Fiz. Tverd. Tela (St. Petersburg) 39, 1030–1034 (June 1997)  相似文献   

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