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1.
Non-aqueous polymer gel electrolytes containing trifluoromethanesulfonic acid (HCF 3SO 3) and polyethylene oxide (PEO) as the gelling polymer has been studied. The increase in conductivity observed with the addition
of PEO to liquid electrolytes has been explained to be due to the breaking of ion aggregates present in electrolytes at higher
acid concentrations. The increase in free H + ion concentration upon breaking of ion aggregates has also been observed in pH measurements and viscosity of gel electrolytes
has been found to increase with PEO addition. Polymer gel electrolytes containing dimethylacetamide (DMA) have σ ∼ 10 −2 S/cm at room temperature and are stable over −50 to 125 °C range of temperature. Gels based on propylene carbonate (PC) and
ethylene carbonate (EC) are stable in the −50 to 40 °C temperature range and loose their gelling nature above 40 °C. 相似文献
2.
Non-aqueous polymer gel electrolytes containing trifluoromethanesulfonic acid (HCF 3SO 3) and polyethylene oxide (PEO) as the gelling polymer has been studied. The increase in conductivity observed with the addition
of PEO to liquid electrolytes has been explained to be due to the breaking of ion aggregates present in electrolytes at higher
acid concentrations. The increase in free H + ion concentration upon breaking of ion aggregates has also been observed in pH measurements and viscosity of gel electrolytes
has been found to increase with PEO addition. Polymer gel electrolytes containing dimethylacetamide (DMA) have σ ∼ 10 −2 S/cm at room temperature and are stable over −50 to 125 °C range of temperature. Gels based on propylene carbonate (PC) and
ethylene carbonate (EC) are stable in the −50 to 40 °C temperature range and loose their gelling nature above 40 °C. 相似文献
3.
The dielectric constant ( ɛ′) and dielectric loss ( ɛ″) for dilute solutions of sulfolane in carbon tetrachloride solution have been measured at 9.885 GHz at different temperatures
viz. 25°C, 30°C, 35°C and 40°C by using standard microwave techniques. Following the single frequency concentration variational
method, the dielectric relaxation time ( τ) and dipole moment (μ) have been calculated. It is found that dielectric relaxation process can be treated as the rate process,
just like the viscous flow. Based on the above studies, monomer structure of sulfolane in carbon tetrachloride has been inferred.
Energy parameters ( ΔH
g
, ΔF
g
, ΔS
g
) for dielectric relaxation process of sulfolane in carbon tetrachloride at 25°C, 30°C, 35°C and 40°C have been calculated
and compared with the corresponding energy parameters ( ΔH
η
, ΔF
η
, ΔS
η
) for the viscous flow. 相似文献
4.
FTIR spectroscopic analysis has been carried out for liquid electrolytes containing lithium —(trifluormethanesulfonimide or
imide) salt as the ion source, a binary solvent composed of γBL and DMF and gel electrolytes containing PMMA. These studies
illustrate that for all electrolytes, the cation (Li +) — solvent interaction is predominant and occurs through the carbonyl oxygen and the electron rich nitrogen atom of the solvating
medium i.e., the binary solvent. Ionic conductivity trends upon varying lithium imide concentration, exhibit a single maximum
in both liquid and gel polymeric electrolytes. The conductivity at 25 °C (σ 25) decline at high salt concentrations attributable to ion aggregation or cation-anion association, has been explained on the
basis of detailed spectral analysis. Addition of PMMA as a gelatinizing agent to liquid electrolytes does not affect the conduction
mechanism drastically, which is evident from conductivity measurements and is supplemented by spectral studies. 相似文献
5.
Plasma resonance in the IR reflection spectra is used to measure the concentration and relaxation time of free charge carriers
along with the conductivity in PbTe 1 − x
Cl
x
solid solutions. It is found that with increasing the chlorine concentration, the electron concentration and conductivity
increase and reach saturation at x = 0.03 ( n = 5.5 × 10 19 cm −3, σ = 3750 Ohm −1 · cm −1). The relaxation time decreases with increasing the chlorine concentration and reaches the minimum value of 2.2 × 10 −14 s at x = 0.03; then, it almost does not change. 相似文献
6.
An attempt has been made in the present work to combine gel and composite polymer electrolyte routes together to form a composite
polymeric gel electrolyte that is expected to possess high ionic conductivity with good mechanical integrity. Polyethylene
glycol (PEG) based composite gel electrolytes using polyvinyl alcohol (PVA) as guest polymer have been synthesized with 1
molar solution of ammonium thiocyanate (NH 4SCN) in dimethyl sulphoxide (DMSO) and electrically characterized. The ionic conductivity measurements indicate that PEG:PVA:NH 4SCN-based composite gel electrolytes are superior ( σ
max = 5.7 × 10 −2 S cm −1) to pristine electrolytes (PEG:NH 4SCN system) and conductivity variation with filler concentration remains within an order of magnitude. The observed conductivity
maxima have been correlated to PEG:PVA:NH 4SCN-and PVA:NH 4SCN-type complexes. Temperature dependence of conductivity profiles exhibits Arrhenius behaviour in low temperature regime
followed by VTF character at higher temperature.
相似文献
7.
The most probable physical models of hydrogen sensors based on thin stannic oxide films, MOS-structures, and tunnel MOS-diodes
are discussed. The emphasis is on the mechanisms of formation of sensor response to hydrogen. The analytical equations describing
the dependence of the response on the hydrogen concentration nH 2 are derived for all types of sensors. The relations describing the dependences of the SnO
2-sensor conductivity and response on the absolute humidity of a gas mixture are given. It is shown that the relaxation time
τ rel of the response of SnO
2-and MOS-structure sensors is determined by the relaxation time τ a of hydrogen atom adsorption on the SnO
2 and SiO
2 surfaces, respectively. For the MOS-diodes, τ rel = τ a at nH 2 and τ rel = τ d at nH 2≥7.5·10 3, where τ d is the relaxation time of hydrogen atom diffusion through an SiO
2 layer.
__________
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 4, pp. 84–98, April, 2008. 相似文献
8.
Nano-composite polymer gel electrolytes were synthesized by using polyethylene oxide (PEO), ammonium tetrafluoroborate (NH4BF4), fumed silica (SiO2), dimethylacetamide (DMA), ethylene carbonate (EC), and propylene carbonate (PC) and characterized by conductivity studies. The effect of donor number of solvent on ionic conductivity of polymer gel electrolytes has been studied. The mechanical strength of the gel electrolytes has been increased with the addition of nano-sized fumed silica along with an enhancement in conductivity. Maximum room temperature ionic conductivity of 2.63 × 10−3 and 2.92 × 10−3 S/cm has been observed for nano-composite gel electrolytes containing 0.1 and 0.5 wt% SiO2 in DMA+1 M NH4BF4+10 wt% PEO, respectively. Nano-composite polymer gel electrolytes having DMA have been found to be thermally and electrically stable over 0 to 90 °C temperature range. Also, the change in conductivity with the passage of time is very small, which may be desirable to make applicable for various smart devices. 相似文献
9.
Polymer nanocomposite electrolytes (PNCEs) of poly(ethylene oxide) and sodium perchlorate monohydrate complexes with montmorillonite
(MMT) clay up to 20 wt.% MMT concentration of poly(ethylene oxide) (PEO) are synthesized by melt compounding technique at
melting temperature of PEO (∼70 °C) and NaClO 4 monohydrate (∼140 °C). Complex dielectric function, electric modulus, alternating current (ac) electrical conductivity, and
impedance properties of these PNCEs films are investigated in the frequency range 20 Hz to 1 MHz at ambient temperature. The
direct current conductivity of these materials was determined by fitting the frequency-dependent ac conductivity spectra to
the Jonscher power law. The PNCEs films synthesized at melting temperature of NaClO 4 monohydrate have conductivity values lower than that of synthesized at PEO melting temperature. The complex impedance plane
plots of these PNCEs films have a semicircular arc in upper frequency region corresponding to the bulk material properties
and are followed by a spike in the lower frequency range owing to the electrode polarization phenomena. Relaxation times of
electrode polarization and ionic conduction relaxation processes are determined from the frequency values corresponding to
peaks in loss tangent and electric modulus loss spectra, respectively. A correlation is observed between the ionic conductivity
and dielectric relaxation processes in the investigated PNCEs materials of varying MMT clay concentration. The scaled ac conductivity
spectra of these PNCEs materials also obey the ac universality law. 相似文献
10.
In this work, the problem of separating the contribution of a strange quark to the proton spin in the process
is studied. Measurements of the quantities Δσ
K
and Δσ ±, where Δσ
M
= dσ
M
(+ +) - dσ
M
(+ -) at small z, and the use of definite combinations of them allow important information on the proton-spin structure to
be obtained.
M. A. Rasulzade Baku State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 21–25, January,
2000. 相似文献
11.
Cubic-stabilized ((DyO 1.5)
x
–(WO 3)
y
–(BiO 1.5) 1 − x − y
) electrolytes (DWSB) with much higher conductivity than (ErO 1.5) 0.2(BiO 1.5) 0.8, 20ESB, were developed through a double-doping strategy. (DyO 1.5) 0.08–(WO 3) 0.04–(BiO 1.5) 0.88, 8D4WSB, is the highest conductivity composition but underwent the greatest conductivity degradation at 500 °C due to its
low total dopant concentration. The effect of dopant composition on conductivity behavior with time at 500 °C demonstrates
that there is a trade-off between initial conductivity and long-term stability at this temperature. Therefore, it is necessary
to find an optimal total and relative concentration of dopants to provide the enhanced long-term stability needed to make
this DWSB electrolyte system feasible for 500 °C operation. To this end, it was found that (DyO 1.5) 0.25–(WO 3) 0.05–(BiO 1.5) 0.70, 25D5WSB, maintained a conductivity of 0.0068 S/cm without appreciable degradation after annealing at 500 °C for 500 h. Moreover,
since bismuth oxide-based electrolytes do not exhibit any grain boundary impedance, the total conductivity of 25D5WSB is significantly
higher than that of alternate electrolytes (e.g., GDC: Gd 0.1Ce 0.9O 1.95) at this temperature. 相似文献
12.
The perovskite structured material LaGaO 3 doped with 10 mol-% strontium and 20 mol-% magnesium was prepared by two different wet-chemical synthesis routes. The total
conductivity was measured in air and under an oxygen partial pressure of 10 −20 bar. There was a decrease by 10 % in 4 days when the atmosphere was changed from air to 10 −20 bar. This process is reversible. Hebb-Wagner measurements resulted in values for the electronic minority charge carrier conductivities
in pure oxygen of log σ h [S/cm]=−4.02 and log σ e [S/cm]=−15.5 for the holes and electrons, respectively, at 600 °C. In the partial pressure range 10 −3 bar≤p(O 2)≤1 bar, a slope of +1/4 was observed for d(log (σ h)) / d(log (p(O 2)) at T=600, 650 and 700 °C. That is in agreement with the assumption of a large number of oxygen vacancies. The diffusion
coefficient of the holes was evaluated from the relaxation curves to be 1.1*10 −7 cm 2/s at 600 °C. Degradation effects were observed under highly reducing conditions which are attributed to the formation of
gallium-platinum alloys and the loss of gallium oxide if O 2 is available in the gas phase.
Paper presented at the 6th Euroconference on Solid State Ionics, Cetraro, Calabria, Italy, Sept. 12–19, 1999. 相似文献
13.
Proton-conducting polymer complex electrolytes were prepared by incorporation of boric acid, H 3BO 3 into poly(vinylalcohol), PVA, to form hydrated PVA xH 3BO 3 where x denotes the number of moles of boric acid per polymer repeat unit. The dried materials were characterized via Fourier transform
infrared spectroscopy, thermogravimetry, and X-ray diffraction. The proton conductivity of the hydrated complex electrolytes
was measured by AC impedance spectroscopy. PVA2H 3BO 3 with RH ∼25% was found to be optimum composition that exhibited proton conductivity of 1.3 × 10 −3 S/cm at 80 °C. 相似文献
14.
The structure and electric conductivity of glasses in the system RNO 3–Zn(NO 3) 2–KHSO 4–P 2O 5 ( R = Na, K) obtained at different temperatures were investigated by IR and impedance spectroscopy. Glasses fused at 250–350 °C demonstrated an increase of their ionic conductivity in 10 3 times in comparison with the same compositions fused at 550 °C. The influence of the chemical composition on the structure and properties of the obtained glasses was analyzed. It is proposed that the high ionic conductivity of glasses obtained at low temperatures is related to the incorporation of the nitrate ions between long (PO 3) n chains, similar to the iodide ions; this resulted in a maximal coordination of the local conduction space for the cation associated with a disordered glass network. 相似文献
15.
Doubly substitution of vanadium by Cu and Co in the limit of 10% in Bi 4V 2O 11, has led to the formation of the Bi 4V 1.8Cu 0.2−xCo xO 10.7 solid solution. X-ray diffraction shows that all the compositions present a tetragonal symmetry. The thermal analysis has
revealed that the polymorph γ' phase, which is formed by a partial ordering of oxygen ions in the γ high temperature form,
is stabilized at room temperature. The influence of sintering temperature on the microstructure of the samples was investigated
by the scanning electron microscopy (SEM). The ceramics sintered at 820 °C for more than 3 hours present micro-craks. The
evolution of the electrical conductivity with temperature and the degree of substitution has been investigated by impedance
spectroscopy. The sample with x=0.1 presents the highest value of the conductivity ≈4.6×10 −2 S·cm −1 at 600 °C. 相似文献
16.
In this paper, we aim to prepare polymer electrolytes consisting of NaI and I 2 dissolved in poly(ethylene oxide) (PEO) and dioctyl phthalate (DOP) as an additive and apply the electrolytes to dye-sensitized
solar cells (DSSC). Upon the incorporation of salt, the phthalic-stretching C=O bands of DOP in Fourier transform infrared
spectra shifted to a lower wave number (Δ f = 93 cm −1), confirming the unusual strong complex formation between sodium ions and phthalic oxygen. Coordinative interactions and
structural changes of PEO/NaI/I 2/DOP electrolytes have also been characterized by wide angle X-ray scattering, presenting an almost amorphous structure of
the polymer electrolytes. The ionic conductivity of the polymer electrolytes reached ∼10 –4 S/cm at room temperature at the mole ratio of [EO]:[Na]:[DOP] = 10:1:0.5, as determined by the four-probe method. DSSC using
the polymer electrolytes and conductive indium tin oxide glasses exhibited 2.9% of overall energy conversion efficiency (= P
max/ P
in × 100) at one sun condition (100 mW/cm 2). The good interfacial contact between the electrolytes and the dye-attached nanocrystalline TiO 2 layers were verified by field-emission scanning electron microscopy. 相似文献
17.
The compounds Cu xNb 3Se 4 (0≤x≤0,45) and H xNb 3Se 4 (0≤x≤2·10 −3) were prepared by electrochemical titration from Nb 3Se 4. The samples were characterized by X-ray analysis and q-probe conductivity measurements as a function of temperature. The
Cu-compound is isostructural with Nb 3Se 4 for 0≤x≤0.2 and shows new phases for 0,2≤x≤0,45. The H-compound shows an impurity controlled conductivity in the temperature
range from 20 to 200 °C and an intrinsic type conductivity in the temperature range from 330 to 450 °C. The activation engines
are 0 and 0.15 eV, respectively. Rapid proton conduction in H xNb 3Se 4 makes it difficult to control the composition as demonstrated by exposure of the samples to different atmospheres. An increasing
H-concentration decreases drastically the conductivity by several orders of magnitude. 相似文献
18.
The dispersion curves of the dielectric response of NH 4HSO 4 show that the corrected imaginary part of permittivity, εʺ, and its real part ε′ versus frequency reveal a dielectric relaxation around 9.1 × 10 5 Hz at 31 °C, which shifts to higher frequencies (∼ 10 6 Hz) as the temperatures increases. The relaxation frequency shows an activated relaxation process over the temperature range 31–83 °C with activation energy Ea = 0.14 eV, which is close to that derived from the dc conductivity. We suggest that the observed dielectric relaxation could be produced by the H + jump and SO 4− reorientation that cause distortion and change the local lattice polarizability inducing dipoles like HSO 4−. 相似文献
19.
Preliminary results on composite gel electrolytes (CGEs) with fumed silica (SiO 2) as filler added to gel polymeric electrolyte (GPE) based on PMMA, LiCF 3SO 3 and PC are presented in this paper. Added fumed silica is seen to enhance the mechanical properties of the GPE without changing
the σ significantly. The high ionic conductivity (×10 −3 S/cm), high transmission in the visible region and nominal variance of σ and ν over a wide temperature window makes these
CGEs potential electrolytes for electrochromic windows (ECWs).
Paper presented at the 2nd International Conference on Ionic Devices, Anna University, Chennai, India, Nov. 28–30, 2003. 相似文献
20.
The ionic and electronic conductivities of Ag 2Tl 6I 10 single crystals have been studied as a function of crystallographic orientation and temperature from 20 to 135°C. EMF as
well as AC and DC techniques have been employed. The highly anisotropic material is predominantly an Ag +-ion conductor parallel to c-direction, with the Ag + ions moving through linear channels that are not interconnected. The conductivity σ ‖c
=1.6×10 −7Ω −1cm −1 at 25°C, with an activation enthalpy for σ ‖c
of 0.38 eV. The conduction perpendicular to c-direction has been found to be predominantly electronic with a value of σ ⊥c
=3×10 −9Ω −1cm −1 at 25°C and an activation enthalpy for σ ⊥c
of 0.64 eV. This is the first observation of one-dimensional Ag + conduction and this type of orientation-dependent change from ionic to electronic conduction.
On leave from Institute of Physics, Academia Sinica, Peking, China. 相似文献
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