共查询到20条相似文献,搜索用时 15 毫秒
1.
T. Zhang L. Kong Z. Zeng H. Huang P. Hing Z. Xia J. Kilner 《Journal of Solid State Electrochemistry》2003,7(6):348-354
A 20% GdO1.5 doped ceria solid solution with a small amount of MnO2 doping (≤5% molar ratio) was prepared via the mixed oxide method from high-purity commercial powders with grain size around
0.2–0.5 μm. X-ray diffraction analysis indicated that all the samples exhibited the fluorite structure, and no new phase was
found. The data from dilatometeric measurements and scanning electron microscopy observations revealed that 1% Mn doping reduced
the sintering temperature by over 150 °C, and enhanced the densification and grain growth. Mn doping has little effect on
grain interior conductivity, but a marked deterioration in grain boundary behavior is observed. This leads to a lower total
conductivity in comparison with the undoped Ce0.8Gd0.2O2–δ. Therefore, for solid oxide fuel cells (SOFCs) with Mn-containing compounds as electrodes, optimization of electrode fabrication
conditions is needed to prevent the formation of a lower conductivity layer at the electrode/electrolyte interface since Mn
will diffuse from the electrode side to the electrolyte during fabrication and operation of SOFCs.
Electronic Publication 相似文献
2.
Chiwei Wang Xiaoling Ma Jinguo Cheng Jutang Sun Yunhong Zhou 《Journal of Solid State Electrochemistry》2007,11(3):361-364
LiNi0.8Co0.2O2 and Ca-doped LiNi0.8Co0.2O2 cathode materials have been synthesized via a rheological phase reaction method. X-ray diffraction studies show that the
Ca-doped material, and also the discharged electrode, maintains a hexagonal structure even when cycled in the range of 3.0–4.35 V
(vs Li+/Li) after 100 cycles. Electrochemical tests show that Ca doping significantly improves the reversible capacity and cyclability.
The improvement is attributed to the formation of defects caused by the partial occupancy of Ca2+ ions in lithium lattice sites, which reduce the resistance and thus improve the electrochemical properties. 相似文献
3.
N. N. Gedam P. R. Padole S. K. Rithe G. N. Chaudhari 《Journal of Sol-Gel Science and Technology》2009,50(3):296-300
Thick film of nanocrystalline Co0.8Ni0.2Fe2O4 was obtained by sol–gel citrate method for gas sensing application. The synthesized powder was characterized by X-ray diffraction
(XRD) and transmission electron microscopy. The XRD pattern shows spinel type structure of Co0.8Ni0.2Fe2O4. XRD of Co0.8Ni0.2Fe2O4 revels formation of solid solution with average grain size of about 30 nm. From gas sensing properties it observed that nickel
doping improves the sensor response and selectivity towards ammonia gas and very low response to LPG, CO, and H2S at 280 °C. Furthermore, incorporation of Pd improves the sensor response and stability of ammonia gas and reduced the operating
temperature upto 210 °C. The sensor is a promising candidate for practical detector of ammonia. 相似文献
4.
5.
N. B. Babanly Yu. A. Yusibov R. J. Mirzoeva Yu. M. Shykhyev M. B. Babanly 《Russian Journal of Electrochemistry》2009,45(4):405-410
The Cu-B-Se (B = In, As, Sb, Bi) systems are studied by measurement of EMF for concentration circuits vs. a copper electrode in the temperature range of 300–430 K. A solid superionic Cu4RbCl3I2 conductor is used as an electrolyte. Diagrams of solid-phase equilibriums in the studied systems are constructed. Partial molar functions of alloyed copper are calculated on the basis of the equations of the temperature dependences of EMF. Potential-forming reactions corresponding to the measured EMF values are determined on the basis of the phase diagrams and standard thermodynamic formation functions and standard entropies of ternary compounds are calculated. 相似文献
6.
M. B. Babanly L. F. Mashadieva G. M. Velieva S. Z. Imamalieva Yu. M. Shykhyev 《Russian Journal of Electrochemistry》2009,45(4):399-404
The EMF method with a solid Ag4RbI5 superionic conductor was used to study the Ag-As-Se and Ag-S-I systems in the composition ranges of Ag2Se-As2Se3-Se and Ag2S-AgI-S, accordingly. Their solid-phase equilibrium diagrams are constructed or specified. The existence of ternary AgAs3Se5, AgAsSe2, Ag3AsSe3, Ag7AsSe6, Ag3SI compounds is confirmed. The standard partial and integral thermodynamic formation functions and also standard entropies were calculated for these compounds for the first time. 相似文献
7.
Within the framework of the density functional theory (DFT), the electronic structure of monooxodioxovanadium functional groups in tetrahedral coordination, which model the active centers (ACs) of fine supported catalysts V2O5/SiO2 and V2O5/TiO2, has been analyzed. The optimal structures of three ACs as possible models of monomeric and polymeric oxovanadium forms on the carriers with low vanadium content were determined. The modified DFT method involving the time dependence of Kohn-Sham equation (TDDFT) was used for the adopted AC models to calculate the energies of the excited states, and optical spectra of the absorption in 25000–60000 cm?1 region were reconstructed on their base. The spectrum in this region is due to O → V charge transfer. The features of electronic spectra with the charge transfer for V2O5/SiO2 and V2O5/TiO2 catalysts and the vibrational spectra of three AC models corresponding to the monomeric and dimeric oxovanadium forms of the supported catalysts V2O5/SiO2 and V2O5/TiO2 were defined. The detailed interpretation of normal vibration frequencies is given. The frequencies typical of the monomeric and dimeric oxovanadium forms on the carrier surface were identified. 相似文献
8.
The impedance of a porous gold electrode in contact with solid electrolyte La0.88Sr0.12Ga0.82Mg0.18O2.85 and the effect of the manufacture conditions on its polarization resistance are studied at 600–800°C in air. The overall oxygen reaction rate on a gold electrode is described as the sum of two partial constituents, namely, the oxygen exchange at the gas/electrolyte interface at the gold/gas/electrolyte triple-phased boundary.Translated from Elektrokhimiya, Vol. 41, No. 2, 2005, pp. 190–197.Original Russian Text Copyright © 2005 by Shkerin, Sokolova, Khlupin, Beresnev.This revised version was published online in April 2005 with corrections to the article note and article title and cover date. 相似文献
9.
Lifen Xiao Yanqiang Zhao Yanyan Yang Xinping Ai Hanxi Yang Yuliang Cao 《Journal of Solid State Electrochemistry》2008,12(6):687-691
LiNi0.5Mn1.5O4 powders were prepared through polymer-pyrolysis method. XRD and TEM analysis indicated that the pure spinel structure was
formed at around 450 °C due to the very homogeneous intermixing of cations at the atomic scale in the starting precursor in
this method, while the well-defined octahedral crystals appeared at a relatively high calcination temperature of 900 °C with
a uniform particle size of about 100 nm. When cycled between 3.5 and 4.9 V at a current density of 50 mA/g, the as prepared
LiNi0.5Mn1.5O4 delivered an initial discharge capacity of 112.9 mAh/g and demonstrated an excellent cyclability with 97.3% capacity retentive
after 50 cycles. 相似文献
10.
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
11.
Nanocrystalline La2Mo2O9 oxide-ion conductor has been successfully synthesized by microwave-assisted combustion method within a very short time duration
using aspartic acid as the newer fuel in a domestic microwave oven. The synthesized nanocrystalline powder showed good sinterability
and reached more than 97% of theoretical density even at low temperature of 800 °C for 5 h. The sintered La2Mo2O9 sample exhibited a conductivity of 0.159 S/cm in air at 750 °C. 相似文献
12.
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
13.
The air,Au/La0.88Sr0.12Ga0.82Mg0.18O2.85/Au,air cells are studied by an impedancemetry method before and after a week-long exposure at 700°C to atmospheres of hydrogen, humid air, and carbon dioxide. Blank specimens of the same electrolyte are examined by methods of x-ray diffraction, Raman scattering (RS), and x-ray photoelectron spectroscopy. The fact that the shape of the RS spectra and the shape of the electrode impedance dispersion alter unequivocally suggests that, at the very least, the electrode surface interacts with all the gases. The interaction in question is reversible in the case of hydrogen and carbon dioxide. In the case of water vapor, the interaction is irreversible.Translated from Elektrokhimiya, Vol. 41, No. 2, 2005, pp. 198–205.Original Russian Text Copyright © 2005 by Shkerin, Kovyazina, Beresnev, Kalashnikova, Martemyanova.This revised version was published online in April 2005 with corrections to the article note and article title and cover date. 相似文献
14.
P. Tabero 《Journal of Thermal Analysis and Calorimetry》2007,88(1):37-41
Solid solution phases of a formula Fe8V10W16–xMoxO85 where 0≤x≤4, have been obtained, possessing a structure
of the compound Fe8V10W16O85.
It was found on the base of XRD and DTA investigations that these solution
phases melted incongruently, with increasing the value of x, in the temperature
range from 1108 (x=0) to 1083 K (x=4) depositing Fe2WO6
and WO3. The increase of the Mo6+
ions content in the crystal lattice of Fe8V10W16O85
causes the lattice parameters a=b contraction with cbeing
almost constant. IR spectra of the Fe8V10W16–xMoxO85 solid solution phases have been recorded. 相似文献
15.
The effect of chemical composition to ionic conductivity and activation energy of vitreous solid electrolytes (SE) based on Li2O-P2O5-LiF system (Li2O ≥ 45.4 mol %) was detected. The temperature effect to conductivity and activation energy was studied. An original technology was designed to prepare vitreous SEs in Li2O-P2O5-LiF system containing up to 20 mol % LiF and characterized with ionic conductivity up to 4.4 × 10?7 S cm?1 (24°C) and activation energy about 0.567 eV. The synthesized materials are characterized with high X-ray amorphism and technological performance. 相似文献
16.
Sagrario M. Montemayor L. A. García-Cerda J. R. Torres-Lubián O. S. Rodríguez-Fernández 《Journal of Sol-Gel Science and Technology》2007,42(2):181-186
In this work the synthesis of CoFe2O4-SiO2 and NiFe2O4-SiO2 nanocomposites was studied via the sol–gel method, using the polymerized complex route. The polymerized precursors obtained
by the reaction of citric acid, ethylene glycol, tetraethylorthosilicate, ferric nitrate, and cobalt nitrate or nickel chloride
were characterized by nuclear magnetic resonance (NMR) and infrared (IR) spectroscopy. NMR and IR spectra of the precursors,
without and with metallic ions, show the formation of polymeric chains with ester and ether groups and complexes of metal-polymeric
precursor. The nanocomposites were obtained by the thermal decomposition of the organic fraction and characterized by X-ray
diffraction (XRD) and vibrating sample magnetometry (VSM). XRD patterns show the formation of CoFe2O4 and NiFe2O4 in an amorphous silica matrix above 400 °C in both cases. When the calcination temperature was 800 °C the particle size of
the crystalline phases, calculated using the Scherrer equation, reached ∼35 nm for the two oxides. VSM plots show the ferrimagnetic
behavior that is expected for this type of magnetic material; the magnetization at 12.5 KOe of the CoFe2O4-SiO2 and NiFe2O4-SiO2 compounds was 29.5 and 17.4 emu/g, respectively, for samples treated at 800 °C. 相似文献
17.
Lei Ge 《Journal of Sol-Gel Science and Technology》2007,44(3):263-268
Novel visible-light-activated In2O3–CaIn2O4 photocatalysts were developed in this paper through a sol–gel method. The photocatalytic activities of In2O3–CaIn2O4 composite photocatalysts were investigated based on the decomposition of methyl orange under visible light irradiation (λ > 400 nm).
The obtained samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive
spectrum (EDS), X-ray photoelectron spectroscopy (XPS) and UV–vis diffused reflectance spectroscopy (DRS). The results revealed
that the In2O3–CaIn2O4 composite samples with different In2O3 and CaIn2O4 content can be obtained by controlling the synthesis temperature, and the composite photocatalysts extended the light absorption
spectrum toward the visible region. The photocatalytic tests indicated that the composite samples demonstrated high visible-light
activity for decomposition of methyl orange. The significant enhancement in the In2O3–CaIn2O4 photo-activity under visible light irradiation can be ascribed to the efficient separation of photo-generated carriers in
the In2O3 and CaIn2O4 coupling semiconductors. 相似文献
18.
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
19.
I. I. Zakharov A. I. Kolbasin O. I. Zakharova I. V. Kravchenko V. I. Dyshlovoi 《Theoretical and Experimental Chemistry》2007,43(1):66-70
By functional density quantum-chemical method (DFT/B3LYP using the 6-311++G(3df)) it has been shown that the molecular structures
of N2O5 with Cs and C2 symmetries are energetically equivalent. It follows from calculations of the vibrational frequencies that both structures
are characterized by potential energy minima and correspond to stationary states of the N2O5 molecule. It is proposed, on the basis of a comparison of the calculated and experimental vibrational spectra of N2O5, that dinitrogen pentaoxide exists in the gas phase as an equimolecular mixture of N2O5 molecules with Cs and C2 symmetry, while in the solid phase it is characterized by the C2 molecular structure.
__________
Translated from Teoreticheskaya I éksperimental’naya Khimiya, Vol. 43, No. 1, pp. 58–63, January–February, 2007. 相似文献
20.
Composition solid electrolytes (1 ? x)LiClO4-xMgO are synthesized and their physicochemical properties are studied. According to the data of differential scanning calorimetry, for sufficiently high oxide concentrations, all lithium perchlorate is present in the composite in the amorphous state. Impedance spectroscopic studies demonstrate that the conductivity of composites passes through a maximum at x = 0.8?0.9, reaching ~10?2 S/cm at 200°C. Based on voltammetric characteristics, it is shown that the voltage of electrochemical decomposition of composites in vacuum does not exceed 3.5–4.0 V, decreasing to 1.8–2.0 V in humid atmosphere. The conductivity of studied composites in vacuum may apparently be attributed to lithium ions, and these solid electrolytes can be used in solid-state electrochemical lithium cells. 相似文献