共查询到20条相似文献,搜索用时 22 毫秒
1.
L. C. Rodrigues M. M. Silva H. I. M. Veiga J. M. S. S. Esperança M. Costa M. J. Smith 《Journal of Solid State Electrochemistry》2012,16(4):1623-1629
In this paper, the preparation and purification of an amorphous polymer network, poly[oxymethylene-oligo(oxyethylene)], designated
as aPEO, are described. The flexible CH2CH2O segments in this host polymer combine appropriate mechanical properties, over a critical temperature range from −20 to 60 °C,
with labile salt-host interactions. The intensity of these interactions is sufficient to permit solubilisation of the guest
salt in the host polymer while permitting adequate mobility of ionic guest species. We also report the preparation and characterisation
of a novel polymer electrolyte based on this host polymer with lithium tetrafluoroborate, LiBF4, as guest salt. Electrolyte samples are thermally stable up to approximately 250 °C and completely amorphous above room temperature.
The electrolyte composition determines the glass transition temperature of electrolytes and was found to vary between −50.8
and −62.4 °C. The electrolyte composition that supports the maximum room temperature conductivity of this electrolyte system
is n = 5 (2.10 × 10−5 S cm−1 at 25 °C). The electrochemical stability domain of the sample with n = 5 spans about 5 V measured against a Li/Li+ reference. This new electrolyte system represents a promising alternative to LiCF3SO3 and LiClO4-doped PEO analogues. 相似文献
2.
Summary. The protonation and deprotonation behaviour and the assignment of pK
a values of hypericin are reviewed and discussed. Three experiments (electrospray MS, 1H NMR, acid–base indicator equilibria) provided additional evidences for the assignment of pK
a values of −5 and −6 to mono- and diprotonation at the carbonyl groups of hypericin, of pK
a = 2 to monodeprotonation at the bay-region, and of pK
a = 11 to dideprotonation at the bay- and peri-regions.
Received September 26, 2001. Accepted October 1, 2001 相似文献
3.
Summary. The two new compounds Mn(dien)2[MoS4] (1) and Mn(dien)2[Mo2O2S6] (2) (dien = diethylenetriamine) were prepared under solvothermal conditions. Both compounds were obtained as phase-pure products. The
structures consist of new [Mn(dien)2]2+ cations and isolated tetrahedral [MoS4]2− (1) or [Mo2O2S6]2− (2) anions. Between the anions and the cations, hydrogen bonding is observed. Compound 1 crystallizes in the tetragonal space group I (a = 10.219(2), c = 9.259(2) ?, Z = 2), whereas 2 crystallizes in the monoclinic space group P21/c (a = 8.703(2), b = 18.390(4), c = 14.603(3) ?, β = 103.18(3)°, Z = 4). The thermal behaviour of the thiomolybdates was investigated using difference thermoanalysis (DTA) and thermogravimetry
(TG). Both compounds decompose under argon with a single endothermic signal in the DTA curve (peak maximum: 252 (1) and 242°C (2)).
Received November 5, 2001. Accepted December 27, 2001 相似文献
4.
Günther Vogg Lex J.-P. Meyer Christian Miesner Martin S. Brandt Martin Stutzmann 《Monatshefte für Chemie / Chemical Monthly》2001,132(10):1125-1135
Summary. Epitaxial thin films of Ca(Si
1 − x
Ge
x
)2 with 0 < x ≤ 1 are found to react with the moisture of ambient atmosphere to form new Ca-Si-Ge-O-H compounds which were studied by X-ray
diffraction, energy dispersive X-ray analysis, infrared absorption, and thermally induced hydrogen desorption measurements.
Pure CaGe2 forms the polygermyne calcium hydroxide intercalation compound Ca(OH)2(GeH)2 upon exposure to humidity, with a trigonal tr6 crystal lattice with a = 4.00(1) and c = 65.3(1)?. In mixed Ca(Si
1 − x
Ge
x
)2 with smaller Ge content, the group-14 layers are subject to intense oxidation leading to decreased crystallinity. The products
exhibit characteristic colours and intense photoluminescence, the peak luminescence varying from 1.35 eV for the reaction
product of Ca(Si0.3Ge0.7)2 to 2.6 eV for that of Ca(Si0.5Ge0.5)2.
Received March 12, 2001. Accepted (revised) May 2, 2001 相似文献
5.
M. Chatelut S. Chah-Bouzziri O. Vittori A. Benayada 《Journal of Solid State Electrochemistry》2000,4(8):435-443
A lead electrode was studied in 6 and 12 M H3PO4. Oxidation of a freshly polished electrode occurred in the −0.5 to −0.3 V vs. SCE range, and led to PbHPO4 growth on the electrode surface. The dissolution of this layer by electrochemical reduction occurred between −0.5 and −0.7 V.
The influence of temperature (20 °C and 65 °C) was investigated and showed that the anodic and the cathodic peaks were increasing,
and more markedly for the 12 M H3PO4. The ratio Q
cathodic/Q
anodic (Q=electrical charge flowing through the electrode) was equal or close to the unity at 20 °C and decreased as the temperature
was increased. The influence of Cl−, Br− and I− ions was also evaluated. The addition of Cl− and Br− predominantly led to Pb5(PO4)3Cl and Pb5(PO4)3Br, respectively, while I− led to a mixture of PbI2 and PbHPO4.
Received: 18 July 1999 / Accepted: 2 November 1999 相似文献
6.
Summary. Small plate-like single crystals of MgAlF5(H2O)2 have been obtained during hydrothermal treatment (270°C) of microcrystalline material prepared by precipitation of stoichiometric
solutions of Al2(SO4)3 · 18H2O and Mg(NO3)2 · 6H2O with diluted hydrofluoric acid. The crystal structure of MgAlF5(H2O)2 has been refined from single crystal data (Imma (# 74), Z = 4, a = 7.0637(7), b = 10.1308(10), c = 6.7745(7) ?, 398 structure factors, 33 parameters, R(F2 > σ(F
2)) = 0.0245, wR(F2 all) = 0.0525). Main features of the inverse weberite type structure are infinite chains of trans-bridged [AlF6] octahedra which are connected via common fluorine atoms by isolated [MgF4(H2O)2] octahedra. MgAlF5(H2O)2 dehydrates at temperatures above 300°C to give MgAlF5. XRPD analysis of this phase has revealed isotypism with FeAlF5. The crystal structure of MgAlF5 (Immm (# 71), Z = 2, a = 7.268(1), b = 6.123(2), c = 3.543(1) ?) is built of infinite chains of edge-sharing [MgF6] octahedra and chains of corner-sharing [AlF6] octahedra along [001]. Upon further heating to temperatures above 500°C, MgAlF5 decomposes to MgF2 and α − AlF3.
Received January 15, 2001. Accepted February 12, 2001 相似文献
7.
Susana H. Tarulli Oscar V. Quinzani Oscar E. Piro Enrique J. Baran Eduardo E. Castellano 《Monatshefte für Chemie / Chemical Monthly》2001,132(7):779-787
Summary. The crystal structure of the title complex, [Cd(tsac)2(H2O)], has been determined by single crystal X-ray diffraction methods. It crystallizes in the monoclinic space group C2/c (a = 12.236(3), b = 8.919(3), c = 16.655(3) ?, β = 96.18(2)°, Z = 4). The molecular structure was solved from 1705 independent reflections with I > σ(I) and refined to R
1 = 0.0489. Infrared and Raman spectra of the complex were recorded and are briefly discussed. Its thermal behaviour was investigated by thermogravimetry
and differential thermal analysis.
Received December 18, 2000. Accepted February 19, 2001 相似文献
8.
Partly loaded magadiite samples have been prepared from a synthetic sodium magadiite, 0.9 Na2O · 13.9 SiO2 · 9.3 H2O, by a two-step intercalation process using n-cetylpyridinium (CP) chloride as a model surfactant. Usually, partly loading with long-chain organic cations yields a non-uniform
distribution of the surfactant molecules in the interlamellar space of the layered silicates. The resulting samples contain
fully expanded crystals or zones within the crystals besides unreacted crystals or domains. After equilibration in water the
partly loaded samples transform into products with a uniform expansion of all interlayer spaces due to rearrangement of the
CP cations within and between the interlayer spaces.
Received: 10 June 1998 Accepted in revised form: 5 November 1998 相似文献
9.
Keiichi Satoh Toshio Suzuki Kiyoshi Sawada 《Monatshefte für Chemie / Chemical Monthly》2001,132(10):1145-1155
Summary. The molecular structures of bis-(pyridine base) complexes of cadmium(II) chloride and bromide, where the pyridine base is pyridine ( py), 3-methylpyridine (3-Me-py), 4-methylpyridine (4-Me-py), and 4-ethylpyridine (4-Et-py), were investigated by means of single-crystal X-ray diffraction and Raman spectroscopy. The crystal structures of CdCl2 py
2 (1), CdCl2(3-Me-py)2 (2), and CdCl2(4-Me-py)2 (3) were determined. All crystals are monoclinic; 1: a = 17.784(2), b = 8.666(1), c = 3.8252(7) ?, β = 91.54(1)°, space group: P21/n; 2: a = 11.89(1), b = 14.41(1), c = 3.874(6) ?, β = 92.3(1)°, space group: P21/a; 3: a = 21.091(2), b = 3.8884(5), c = 18.2317(3) ?, β = 113.64(1)°, space group: C2/c. The structures were refined to R/R
w
values (%) of 3.2/5.5, 3.0/5.0, and 3.4/5.1 for 1–3. All cadmium atoms are octahedrally coordinated with the chloride ions forming infinite di-μ-chloro polymeric linear chains
and the nitrogen atoms of the pyridine base in trans configuration. The Cd chains are oriented along the c-axis in 1 and 2 and along the b-axis in 3. The crystal structures indicate the absence of a peculiar interaction between the polymeric chains. The Raman spectra of eight complexes were measured in the range of 550–50 cm−1, and the Raman peaks originating from cadmium-halogen vibrations were assigned. The Raman spectra of 1 and 2 are quite alike in the lattice mode vibration region. The resemblance of the cadmium-halogen vibration peaks indicates the
same halogenide ion bridged octahedral structure for all complexes.
Received March 27, 2001. Accepted (revised) June 19, 2001 相似文献
10.
Jakub Čížek Ivan Procházka Radomír Kužel Rinat K. Islamgaliev 《Monatshefte für Chemie / Chemical Monthly》2002,133(6):873-887
Summary. Ultra-fine grained (UFG) Cu (grain size 80 nm) containing 0.5 wt.% Al2O3 nanoparticles (size 20 nm) was prepared by high pressure torsion (HPT). Positron lifetime spectroscopy was employed to characterize
the microstructure of this material, especially with respect to types and concentration of lattice defects. The evolution
of microstructure with increasing temperature was studied by positron lifetime spectroscopy and X-ray diffraction measurements.
The thermal stability of the Cu + 0.5 wt.% Al2O3 nanocomposite was compared with that of pure UFG Cu prepared by the same technique. The processes taking place during thermal
recovery of the initial nanoscale structure in both studied materials are described.
Received October 5, 2001. Accepted (revised) December 20, 2001 相似文献
11.
Gerhard Kahl Elisabeth Schöll-Paschinger Andreas Lang 《Monatshefte für Chemie / Chemical Monthly》2001,132(11):1413-1432
Summary. Compared to the simple one-component case, the phase behaviour of binary liquid mixtures shows an incredibly rich variety
of phenomena. In this contribution we restrict ourselves to so-called binary symmetric mixtures, i.e. where like-particle interactions are equal (Φ11(r) = Φ22(r)), whereas the interactions between unlike fluid particles differ from those of likes ones (Φ11(r) ≠ Φ12(r)). Using both the simple mean spherical approximation and the more sophisticated self-consistent Ornstein-Zernike approximation, we have calculated the structural and thermodynamic properties of such a system and determine phase diagrams,
paying particular attention to the critical behaviour (critical and tricritical points, critical end points). We then study
the thermodynamic properties of the same binary mixture when it is in thermal equilibrium with a disordered porous matrix
which we have realized by a frozen configuration of equally sized particles. We observe – in qualitative agreement with experiment
– that already a minute matrix density is able to lead to drastic changes in the phase behaviour of the fluid. We systematically
investigate the influence of the external system parameters (due to the matrix properties and the fluid–matrix interactions)
and of the internal system parameters (due to the fluid properties) on the phase diagram.
Received June 27, 2001. Accepted July 2, 2001 相似文献
12.
S. Durón R. Rivera-Noriega M. A. Leyva P. Nkeng G. Poillerat O. Solorza-Feria 《Journal of Solid State Electrochemistry》2000,4(2):70-74
A ruthenium-sulfur carbonyl cluster electrocatalyst, Ru
x
S
y
(CO)
n
, was synthesized by pyrolysis of Ru3(CO)12 and elemental sulfur in a sealed ampoule at 300 °C. The pyrolyzed compound was characterized by DSC, FT-IR, XRD and SEM (EDX)
techniques. The electrocatalytic activity and kinetic parameters for the molecular oxygen reduction were determined by a rotating
ring-disk electrode (RRDE) in a 0.5 M H2SO4 solution at 25 °C. The cathodic polarization indicates two Tafel slopes: −0.124 ± 0.002 V dec−1 at low and −0.254 ± 0.003 V dec−1 at high overpotentials, and first-order kinetics with respect to O2 concentration. From the analysis of Levich plots and RRDE results, the oxygen reduction on Ru
x
S
y
(CO)
n
was determined to proceed mostly via a multielectron transfer path (4e−) to water formation ( >94%).
Received: 4 March 1999 / Accepted: 26 May 1999 相似文献
13.
A quaternary super-ion-conducting system, 20CdI2 − 80[xAg2O − y(0.7V2O5 − 0.3B2O3)] where 1 ≤ x/y ≤ 3, has been prepared by melt quenching technique. The electrical conductivity measured was the order of 10−4 S/cm at room temperature. The values of silver-ion transport number obtained by electromotive force technique are nearly
unity. The thermoelectric power and electrochemical studies were done on the CdI2–Ag2O–V2O5–B2O3 system. The discharge and polarization characteristics were examined for different cathodes to evaluate the utility of these
cells as power sources for low energy applications. 相似文献
14.
Ashraf A. Mohamed Saleh A. Ahmed Mohamed F. El-Shahat 《Monatshefte für Chemie / Chemical Monthly》2002,133(1):31-40
Summary. A highly selective, sensitive, and simple catalytic method for the determination of molybdenum in natural and waste waters
was developed. It is based on the catalytic effect of Mo(VI) on the oxidation of 2-aminophenol with H2O2. The reaction is monitored spectrophotometrically by tracing the oxidation product at 430 nm after 10 min of mixing the reagents.
Addition of 800 μg · cm−3
EDTA conferred high selectivity; however, interfering effects of Au(III), Cr(III), Cr(VI), and Fe(III) had to be eliminated by
a reduction and co-precipitation procedure with SnCl2 and Al(OH)3. Mo(VI) shows a linear calibration graph up to 11.0 ng · cm−3; the detection limit, based on the 3S
b-criterion, is 0.10 ng · cm−3. The unique selectivity and sensitivity of the new method allowed its direct application to the determination of Mo(VI) in
natural and waste waters.
Received April 11, 2001. Accepted (revised) June 18, 2001 相似文献
15.
Eduardo Marafon Lauro T. Kubota Yoshitaka Gushikem 《Journal of Solid State Electrochemistry》2009,13(3):377-383
SiO2/ZrO2/C carbon ceramic material with composition (in wt%) SiO2 = 50, ZrO2 = 20, and C = 30 was prepared by the sol–gel-processing method. A high-resolution transmission electron microscopy image
showed that ZrO2 and the graphite particles are well dispersed inside the matrix. The electrical conductivity obtained for the pressed disks
of the material was 18 S cm−1, indicating that C particles are also well interconnected inside the solid. An electrode modified with flavin adenine dinucleotide
(FAD) prepared by immersing the solid SiO2/ZrO2/C, molded as a pressed disk, inside a FAD solution (1.0 × 10−3 mol L−1) was used to investigate the electrocatalytic reduction of bromate and iodate. The reduction of both ions occurred at a peak
potential of −0.41 V vs. the saturated calomel reference electrode. The linear response range (lrr) and detection limit (dl)
were: BrO3
−, lrr = 4.98 × 10−5–1.23 × 10−3 mol L−1 and dl = 2.33 μmol L−1; IO3
−, lrr = 4.98 × 10−5 up to 2.42 × 10−3 and dl = 1.46 μmol L−1 for iodate. 相似文献
16.
The numerical properties of the radial part of overlap integrals with the same screening parameters in the form of polynomials
in p = ξR over Slater-type orbitals have been studied and obtained by using three different methods. For that purpose, the characteristics
of auxiliary functions were used first, then Fourier transform convolution theorem, and recurrence relations for the basic
coefficients of A
s
n
l
λ,
n
′
l
′λ were used. The calculations of the radial part of overlap integrals with the same screening parameters were made in the range
1 ≤ n ≤ 75, 1 ≤ n′ ≤ 75, and 10−6 ≤ p.
Received: 18 January 2001 / Accepted: 5 April 2001 / Published online: 27 June 2001 相似文献
17.
Matthias Weil Franz Werner Frank Kubel 《Monatshefte für Chemie / Chemical Monthly》2002,133(3):267-275
Summary. Single crystals of MgAl2F8(H2O)2 have been obtained under hydrothermal conditions (250°C, 14 d) from a starting mixture of AlF3 and MgAlF5(H2O)2 in a 5% (w/w) HF solution. The crystal structure has been determined and refined from single crystal data (Fmmm (#69), Z = 4, a = 7.2691(7), b = 7.0954(16), c = 12.452(2) ?, 281 structure factors, 27 parameters, R(F
2 > 2σ (F
2)) = 0.0282, wR(F
2 all) = 0.0885). The obtained crystals were systematically twinned according to (010/100/001) as twinning matrix, reflecting
the pseudo-tetragonal metric. The crystal structure is composed of perowskite-type layers built of corner sharing AlF6 octahedra with an overall composition of AlF4
− which are connected via common fluorine atoms of [MgF4/2(H2O)2/1] octahedra. Group-subgroup relations of MgAl2F8(H2O)2 to WO3(H2O)0.33 and to other M(II)M(III)2 F8(H2O)2 structures are briefly discussed. Above 570°C, MgAl2F8(H2O)2 decomposes under elimination of water into α-AlF3, β-AlF3, and MgF2.
Received October 29, 2001. Accepted (revised) December 6, 2001 相似文献
18.
Franz Pertlik 《Monatshefte für Chemie / Chemical Monthly》2001,132(12):1509-1513
Summary. Single crystals of K2Ag12Te7 (a = 11.460(2), c = 4.660(1) ?; V = 530.01 ?3; space group: P63/m; Z = 1) were synthesized under hydrothermal conditions at 250°C in concentrated aqueous KOH solution from elementary silver
and tellurium. The crystal structure is characterized by trigonal prismatic KTe6 polyhedra, connected via two common faces to KTe3 rods parallel to [001]. These rods are combined by two crystallographically independent Ag atoms, each coordinated to four
Te and three Ag atoms (Ag–Te and Ag–Ag < 3.1 ?) to a framework of the formula (K2Ag12Te6)2 + and with channels parallel to the sixfold axis. These channels are statistically occupied by one further Te atom per unit
cell, distributed over two independent positions.
Received May 17, 2001. Accepted (revised) July 3, 2001 相似文献
19.
Paul David William Bottomley Stéphane Brémier Dimitri Papaioannou Clive Thomas Walker 《Mikrochimica acta》2002,139(1-4):27-38
The degraded fuel rod bundle from the second Phebus test (FPT1) was examined at ITU, Karlsruhe. Metallographic and microprobe
analysis of the degraded fuel pieces were carried out. The fuel samples from the upper bundle and cavity edge were porous
and had remnants of thick oxidised cladding adhering to them. Electron microprobe analysis line scans across the cladding-fuel
interface showed interdiffusion of U and Zr, with U diffusing down the grain boundaries of the oxidised cladding, while point
analyses revealed noticeable amounts of Zr (1.5–4.2 wt%) in the UO2 fuel. EPMA oxygen measurements revealed in the upper part of the bundle a superstoichiometry of x = 0.3–0.4 in UO
2 + x
, indicating that fuel fragments in this position had undergone considerable oxidation. X-ray diffraction of the corium pool
disclosed a deformed cubic fluorite lattice of UO2. The lattice parameter of a = 5.2984 ? was considerably reduced compared with pure, stoichiometric UO2 and was consistent with a lattice containing approximately 45 mol% ZrO2 that had undergone little oxidation. The corium’s nominal composition of (U0.5Zr0.5) O2 also corresponded to its observed single phase microstructure. 相似文献
20.
Aleksey A. Yaremchenko Vladislav V. Kharton Evgeny N. Naumovich Alim A. Vecher 《Journal of Solid State Electrochemistry》1998,2(3):146-149
The minimum concentration of niobium to stabilize the fluorite-type f.c.c. phase in the Bi2O3–Nb2O5 oxide system at temperatures below 996 K was ascertained to be about 10 mol%. Thermal expansion, electrical conductivity
and crystal lattice parameters of the Bi(Nb)O1.5+δ solid solutions decrease with increasing niobium content. Thermal expansion coefficients were calculated from the dilatometric
data to be (10.314.5)×10−6 K−1 at temperatures in the range 300–700 K and (17.526.0)×10−6 K−1 at 700–1100 K. The conductivity of the Bi1−
x
Nb
x
O1.5+δ ceramics is predominantly ionic. The p-type electronic transference numbers of the Bi(Nb)O1.5+δ solid solutions in air were determined to be less than 0.1. Annealing at temperatures below 900 K results in a sharp decrease
in conductivity of the Bi1−
x
Nb
x
O1.5+δ ceramics.
Received: 18 August 1997 / Accepted: 20 October 1997 相似文献