共查询到20条相似文献,搜索用时 15 毫秒
1.
N. N. Pestereva A. V. Potashnikova K. Yu. Shunyaev A. Ya. Neiman 《Russian Journal of Electrochemistry》2007,43(6):714-720
For the first time ever it is demonstrated in this work that, in spontaneous conditions and following the imposition of an electric field, mutual penetration of components of WO3 and Me2(WO4)3 occurs at heterophase interfaces WO3|Me2(WO4)3 where Me = In, Eu, or Sc. Tungstic oxide WO3 is pulled onto the inner surface of ceramic Me2(WO4)3 and, in turn, components of Me2(WO4)3 penetrate onto the surface of grains of ceramic WO3, which is confirmed by the method of x-ray—fluorescence analysis. Data concerning the conductivity and transport numbers of Eu2(WO4)3 and a composite on its basis, which was manufactured as a result the electrosurface transport of WO3, are obtained for the first time ever. With allowance made for the data on the O2? character of the ionic conduction in MeWO4 and Eu2(WO4)3 it is concluded that the type of ionic carriers in tungstates (Me n+)2/n [WO4] makes no impact on the mechanism of spontaneous and field-induced processes that are developing at the (Me n+)2/n [WO4]|WO3 interfaces. 相似文献
2.
Vibrational spectra of finely divided amorphous CsHSO4,Cs5H3(SO4)4 · H2O, and composites based on these are measured and analyzed. An analysis of the spectra indicates the occurrence of substantial changes in the system of hydrogen bonds and in the spectral range of the sulfate group of acid sulfates in the composites. Structural dynamics of the SO4 tetrahedrons is in full conformance with protonic conduction and the data of x-ray diffraction analyses accompanied by differential scanning calorimetry. It is shown that mobility of protons in the composites increases. A mechanism of the formation of the composites and their conduction is proposed.__________Translated from Elektrokhimiya, Vol. 41, No. 5, 2005, pp. 640–645.Original Russian Text Copyright © 2005 by Ponomareva, Lavrova, Burgina. 相似文献
3.
2CaO·3B2O3·H2O which has non-linear optical (NLO) property was synthesized under hydrothermal condition and identified by XRD, FTIR and
TG as well as by chemical analysis. The molar enthalpy of solution of 2CaO·3B2O3·H2O in HCl·54.572H2O was determined. From a combination of this result with measured enthalpies of solution of H3BO3 in HCl·54.501H2O and of CaO in (HCl+H3BO3) solution, together with the standard molar enthalpies of formation of CaO(s), H3BO3(s), and H2O(l), the standard molar enthalpy of formation of −(5733.7±5.2) kJ mol−1 of 2CaO·3B2O3·H2O was obtained. Thermodynamic properties of this compound were also calculated by a group contribution method. 相似文献
4.
Atomic models are proposed for nanotubes of the titanium silicocarbides Ti2SiC, Ti3SiC2, and Ti4SiC3, and their electronic structure and interatomic interactions are investigated by the density functional tight-binding method
(DFTB) in comparison with the corresponding crystalline phases.
Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 45, No. 2, pp. 88-92, March-April, 2009. 相似文献
5.
Virginie Gueu Hongpeng You Tomokatsu Hayakawa Masayuki Nogami 《Journal of Sol-Gel Science and Technology》2007,41(3):231-236
Fluorescence and spectral hole burning properties of Eu3+ ions were studied in nanocrystals-precipitated SnO2-SiO2 glasses. The glasses were prepared to contain various amount of Eu2O3 using the sol-gel method, in which SnO2 nanocrystals were precipitated by heating in air. In the glasses containing Eu2O3 less than 1%, the Eu3+ ions were preferentially doped in the SnO2 nanocrystals and their fluorescence intensities were enhanced by the energy transfer due to the recombination of electrons
and holes excited in SnO2 crystals. The SnO2 nanocrystals-precipitated glasses exhibited the persistent spectral holes with the depth of ∼25% of the total fluorescence
intensities of the Eu3+ ions. With the increasing Eu2O3 concentration, the amount of SnO2 nanocrystals decreased and the Sn4+ ions formed the random glass structure together with the silica network. This structure change induced the fluorescence intensities
and the hole depth to decrease. 相似文献
6.
Inorganic-organic hybrid membranes containing silica as the structure matrix, poly(N-vinylpyrrolidone) (PVP) as the organic mediating agent and silver ions as olefinic carriers were prepared using sol–gel method and dip-coating process. The structure and permeances of the membranes for N2, He, C2H4, C2H6 at different temperatures indicated that defect-free membranes were obtained and the transportation of the C2H4 through the membranes followed the dissolution and diffusion mechanism. Ideal separation factors of C2H4/C2H6 through the membranes were evaluated at the temperature of 298, 373 and 423 K respectively using mixture gas of 50% C2H4-50% C2H6. The results showed that the ideal separation factors of C2H4/C2H6 through the membranes were obviously greater than the ratio of PC2H4/PC2H6 obtained from the single gas measurement due to the hindering effect by the adsorbed C2H4. The ideal separation factors of C2H4/C2H6 increased with temperature and reached 10 at 423 K, which suggested that C2H4 and C2H6 could be separated at lower humidity compared to the reported organic polymer/silver salt membranes in which humidified gases and higher silver loading were usually used. The transport of C2H4 in the inorganic-organic hybrid membrane was proposed to follow the hopping mechanism, that is, olefins moved across the fixed silver sites. 相似文献
7.
V. M. Zainullina V. L. Volkov N. V. Podvalnaya A. L. Ivanovskii 《Journal of Structural Chemistry》2005,46(2):340-342
The calculations of the electronic structure of layered polyvanadate K2V3O8 were made employing the spin-polarized tight-binding LMTO method. Calculated magnetic moment for K4V6O16 compound phase equals 1.97 μB. V-O interactions were established to be dominating in the chemical bonding generation in this polyvanadate according to the estimated crystal orbital overlap population. The covalent bonds V(2)-V(2) in V(2)2O7 groups and electron density localization on vanadium atoms in isolated pyramids V(1)O5 were found. 相似文献
8.
The reaction mechanism of (CH3)3CO. radical with NO is theoretically investigated at the B3LYP/6-31G* level. The results show that the reaction is multi-channel
in the single state and triplet state. The potential energy surfaces of reaction paths in the single state are lower than
that in the triple state. The balance reaction: (CH3)3CONO⇔(CH3)3CO.+NO, whose potential energy surface is the lowest in all the reaction paths, makes the probability of measuring (CH3)3CO. radical increase. So NO may be considered as a stabilizing reagent for the (CH3)3CO. radical. 相似文献
9.
Areas of fusion and crystallization peaks of K3TaO2F4 and KTaF6 were measured using the DSC mode of a high-temperature calorimeter (SETARAM 1800 K). On the basis of these quantities, considering
the temperature dependence of the calorimeter sensitivity, values of the fusion enthalpy of K3TaO2F4 at the fusion temperature of 1181 K of (43 ± 4) kJ mol−1 and of KTaF6 at the fusion temperature of 760 K of (8 ± 1) kJ mol−1 were determined. 相似文献
10.
The surface of the spinel LiMn2O4 was coated with AlF3 by a chemical process to improve its electrochemical performance at high temperatures. The morphology and structure of the
original and AlF3-coated LiMn2O4 samples were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM). All the samples exhibited
a pure cubic spinel structure without any impurities in the XRD patterns. It was found that the surfaces of the original LiMn2O4 samples were covered with a nanolayer AlF3 after the treatment. The charge/discharge of the materials were carried at 220 mA/g in the range of 3.0 and 4.4 V at 55°C.
While the original LiMn2O4 showed 17.8% capacity loss in 50 cycles at 55°C, the AlF3-coated LiMn2O4 (118.1 mA h/g) showed only 3.4% loss of the initial capacity (122.3 mA h/g) at 55°C. It is obvious that the improvement in
cycling performance of the coated-LiMn2O4 electrode at 55°C is attributed to the presence of AlF3 on the surface of LiMn2O4.
Published in Russian in Elektrokhimiya, 2009, Vol. 45, No. 7, pp. 817–819.
The article is published in the original 相似文献
11.
Li XiaoHong Dong JinLing Xiao HanShuang Lu PeiDong Hu YongAn Zhang YunHong 《中国科学B辑(英文版)》2008,51(2):128-137
The efflorescence and deliquescence processes of Mg(NO3)2 aerosol particles deposited on ZnSe substrate have been investigated through in situ Fourier transform infrared-attenuated total reflection (FTIR-ATR) technique at the molecular level. At relative humidity
(RH) of ∼3%, Mg(NO3)2 particles existed as amorphous states. The amorphous Mg(NO3)2 particles were transformed into crystalline Mg(NO3)2 · nH2O (n ≤ 5) with slight increasing of RH. Thermodynamically stable Mg(NO3)2·6H2O crystals were gradually formed on the particle surface and started to be dissolved at the saturation point (∼53% RH). At
the same time, a continuous phase transition from Mg(NO3)2 · nH2O (n≤5) to Mg(NO3)2·6H2O occurred on the particle surface. This led the solid particles to completely deliquesce at 76% RH, which was much higher
than the saturation point of 53% RH. In the efflorescence process, Mg(NO3)2 droplets entered into the supersaturated region due to the gradual evaporation of water. Finally, amorphous particles were
formed when RH decreased below 5%. In the FTIR-ATR spectra of the supersaturated Mg(NO3)2 droplets, the absorbance of the symmetric stretching vibration of NO
3
−
(v
1- NO
3
−
) clearly became stronger. It resulted from the continuous formation of solvent share ion pairs (SIPs), and even the contact
ion pairs (CIPs) between Mg2+ and NO
3
−
.
Supported by the Trans-Century Program Foundation for the Talents by the Ministry of Education of China, the National Natural
Science Foundation of China (Grant Nos. 20073004, 20473012, and 20673010), the 111 Project (B07012), and the State Key Laboratory
of Physical Chemistry for Solid Surface of Xiamen University 相似文献
12.
V. K. Yatsimirskii V. V. Lesnyak I. N. Gut O. Yu. Boldyreva 《Theoretical and Experimental Chemistry》2005,41(5):329-333
We have shown that WO3 and MoO3 with Pt or Pd additives exhibit high catalytic activity in the reaction of H2 oxidation. In the temperature range 313 K to 353 K, we have studied the kinetic behavior of the reaction on 0.1 mass % Pt(Pd)/WO3 and Pt(Pd)/MoO3 samples. We have established that the kinetics of H2 oxidation on these catalysts correspond to an Eley - Rideal mechanism.
__________
Translated from Teoreticheskaya i Eksperimental'naya Khimiya, Vol. 41, No. 5, pp. 313–316, September–October, 2005. 相似文献
13.
Ben Hui Wang Ji De Wang RuiQuan Liu Ya Hong Xie Zhi Jie Li 《Journal of Solid State Electrochemistry》2007,11(1):27-31
A new type of oxide–salt composite electrolyte, yttrium doped ceria YDC–Ca3(PO4)2–K3PO4, was developed and demonstrated for its promising use for ammonia synthesis. Using this composite electrolyte, ammonia was
synthesized from nitrogen and natural gas at atmospheric pressure in the solid-state proton conducting cell reactor, and the
optimal condition for ammonia production was determined . The evolved rate of ammonia is up to 6.95×10−9 mol s−1 cm−2. 相似文献
14.
A. V. Shlyakhtina A. E. Ukshe L. G. Shcherbakova 《Russian Journal of Electrochemistry》2005,41(3):265-269
A nanoceramic product of the composition Lu2Ti2O7 is synthesized by a coprecipitation method with a subsequent sublimation drying and an annealing at 650–1650°C. The conduction of Lu2Ti2O7 synthesized at 1650°C is ionic (10–3 S cm–1 at 800°C). Thus, a new material with a high ionic conduction has been discovered. The ordering in Lu2Ti2O7 is studied by methods of RFA, RSA, IK spectroscopy, electron microscopy, and impedance spectroscopy. The existence of a low-temperature phase transition fluorite-pyrochlore at 800°C and a high-temperature conversion order-disorder at 1650°C are established.Translated from Elektrokhimiya, Vol. 41, No. 3, 2005, pp. 298–303.Original Russian Text Copyright © 2005 by Shlyakhtina, Ukshe, Shcherbakova. 相似文献
15.
Anna Blonska-Tabero 《Journal of Thermal Analysis and Calorimetry》2007,88(1):201-205
Thermal properties of Co2FeV3O11
have been reinvestigated. It has been proved that this compound does not exhibit
polymorphism. It melts incongruently at the temperature of 770±5°C
and the phase with lyonsite type structure is the solid product of this melting.
Phase relations in the whole subsolidus area of the CoO–V2O5–Fe2O3 system have been determined. The solidus area projection onto
the component concentration triangle plane of this system has been constructed
using the DTA and XRD methods. 15 subsidiary subsystems can be distinguished
in this system. 相似文献
16.
Pinyang Fang Huiqing Fan Shaojun Qiu Liajun Liu Jin Chen 《Journal of Sol-Gel Science and Technology》2009,50(3):290-295
Lanthanum-modified bismuth titanate (Bi3.25La0.75Ti3O12, BLTO) powders were prepared by the complex polymerization method. The structure and morphology of BLTO powders were investigated
by X-ray diffraction and scanning electron microscopy. The complexation of citric acid with the metallic cations was detected
by Fourier transformed infrared (FT-IR). The thermal analyses of obtained gels were investigated by differential thermal gravimetric
(DTG). The pure and normally stoichiometric phase of BLTO powders could be obtained at relatively low temperature of 550–700 °C
even if the bismuth content is not excess in the starting precursors, while the secondary phase could be detected at lower
and higher calcination temperatures. The shape of the BLTO grains is similarly to platelet in Bi-layer structure and stoichiometry
BLTO was detected by the analysis of energy dispersive spectrometry. 相似文献
17.
Ca3Co4O9 powder was prepared by a polyacrylamide gel route in this paper. The effect of the processing on microstructure and thermoelectric
properties of Ca3Co4O9 ceramics via spark plasma sintering were investigated. Electrical measurement shows that the Seebeck coefficient and conductivity
are 170 μV/K and 128 S/cm, respectively, at 700 °C, yielding a power factor value of 3.70 × 10−4 W m−1 K−2 at 700 °C, which is larger than that of Ca3Co4O9 ceramics via solid-state reaction processing. The polyacrylamide gel processing is a fast, cheap, reproducible and easily
scaled up chemical route to improve the thermoelectric properties of Ca3Co4O9 ceramics by preparing the homogeneous and pure Ca3Co4O9 phase. 相似文献
18.
Using Fe3O4 nano-particles as seeds, a new type of Fe3O4/Au composite particles with core/shell structure and diameter of about 170 nm was prepared by reduction of Au3+ with hydroxylamine in an aqueous solution. Particle size analyzer and transmission electron microscope were used to analyze
the size distribution and microstructure of the particles in different conditions. The result showed that the magnetically
responsive property and suspension stability of Fe3O4 seeds as well as reduction conditions of Au3+to Au0are the main factors which are crucial for obtaining a colloid of the Fe3O4/Au composite particles with uniform particle dispersion, excellent stability, homogeneity in particle sizes, and effective
response to an external magnet in aqueous suspension solutions. UV-Vis analysis revealed that there is a characteristic peak
of Fe3O4/Au fluid. For particles with d(0.5)=168 nm, the λmax is 625 nm. 相似文献
19.
Nanocrystalline BiFe0.6Mn0.4O3 powders were synthesized by sol–gel citrate method and studied for gas sensing behavior to reducing gases such as LPG, CO,
CH4 and NH3. The composition and the structure of the powders have been investigated by means of XRD and TEM. The result shows that the
BiFe0.6Mn0.4O3 powders have a rhombohedral distorted perovskite structure with an average crystallite size of 35–40 nm. The BiFe0.6Mn0.4O3-based LPG sensor shows better sensitivity at an operating temperature of 250 °C. The dispersion of Pd on BiFe0.6Mn0.4O3 in the ratio of 0.8 wt.% improved the sensitivity, selectivity and response time. In addition, it reduced the operating temperature
from 250 to 210 °C for LPG sensor. The response time for LPG was less than 1 min. 相似文献
20.
Fe3O4 nanorods and Fe2O3 nanowires have been synthesized through a simple thermal oxide reaction of Fe with C2H2O4 solution at 200–600°C for 1 h in the air. The morphology and structure of Fe3O4 nanorods and Fe2O3 nanowires were detected with powder X-ray diffraction, scanning electron microscopy and transmission electron microscopy.
The influence of temperature on the morphology development was experimentally investigated. The results show that the polycrystals
Fe3O4 nanorods with cubic structure and the average diameter of 0.5–0.8 μm grow after reaction at 200–500°C for 1 h in the air.
When the temperature was 600°C, the samples completely became Fe2O3 nanowires with hexagonal structure. It was found that C2H2O4 molecules had a significant effect on the formation of Fe3O4 nanorods. A possible mechanism was also proposed to account for the growth of these Fe3O4 nanorods.
Supported by the Fund of Weinan Teacher’s University (Grant No. 08YKZ008), the National Natural Science Foundation of China
(Grant No. 20573072) and the Doctoral Fund of Ministry of Education of China (Grant No. 20060718010) 相似文献