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为了解决固体氧化物燃料电池（SOFC）陶瓷连接材料的低成本制备难题，设计了与LaCrO3基连接材料和Ni基阳极均具有良好烧结匹配性能的新型复合材料NiO／La0．7Ca0.3Cr0.97O3—6（LCC97）作为管式SOFC的支撑体．详细研究了NiO含量（5wt％、25wt％、50wt％、75wt％）对复合支撑体的烧结性能、微观组织、孔隙率、电导性能、热膨胀系数等的影响，结果表明：LCC97与NiO具有优良的烧结和化学匹配性能，NiO／LCC97（1：1，wt％）具有最优的综合性能．以其为支撑体，采用浆料浸渍法制备LCC97湿膜，1400℃空气条件下共烧，获得了致密LCC97连接材料薄膜．

The preparation of high-quality yttria-stabilized zirconia (YSZ) electrolyte films on porous substrates is critical to the fabrication of high-performance solid-state ionic devices such as solid oxide fuel cells (SOFCs) and gas sensors. In this paper, stable, fully dispersed YSZ suspensions were prepared. Particles zeta-potential and relative viscosity of suspensions were investigated. Thin YSZ films were deposited on NiO–YSZ anode supports with the YSZ suspensions and then heated to 1400 °C in air. Dense and crack-free films were obtained with thickness in the range of 20–30 μm. La0.8Sr0.2MnO3 (LSM) paste was printed on the YSZ electrolyte/anode to assemble single fuel cell and tested in the temperature range of 650–800 °C. The open circuit voltage (OCV) of the cells reached 0.98 V and maximum power density 190 mW/cm2 at 800 °C, showing a reasonable performance. The deposited thin films could be considered for electrolyte application in intermediate temperature SOFCs.

SrFeCo 0.5 O 3.25+δ powders have been successfully synthesized from SrCO 3 , 2CoCO 3 ·3Co(OH) 2 ·xH 2 O and Fe 2 O 3 based on using the principle of gelcasting. Thermal decomposition of the gelcasting powder was analyzed by differential thermal analysis and thermogravimetry. The crystal structure of the sintered body was investigated by X-ray diffraction. It was found that SrFeCo 0.5 O 3.25+δ samples formed by sintering the gelcasting powder over 1000°C consist mainly of the perovskite phase SrFe 1-x Co x O 3-δ . Electrical conductivity was measured by a DC four-probe technique and oxygen permeation flux was measured by applying oxygen partial pressure difference to a 1.4 mm thick pellet. Both the electrical conductivity and oxygen permeation flux of the gelcasting samples were much higher than that of samples prepared by a traditional solid state reaction method. Though further work should be performed on the higher transfer velocity of electron and oxygen ion, experimental data shows that the gelcasting process is a promising technique for the preparation of mixed conducting SrFeCo 0.5 O 3.25+δ .

Although a lot of work has been done on electroless nickel coating, work on preparing asymmetric nickel membranes on porous ceramic supports is rarely reported. In this work, microfiltration nickel membranes are prepared on porous alumina supports with electroless plating. A new approach technique, sol–gel process is used to activate the alumina supports. The coated membranes were investigated by means of scanning electron microscopy and gas permeation test. Membrane thickness and amount of nickel increase with plating time. Membrane pore size decreases greatly as electroless coating is processed for 15 min. After 15-min coating the pore size decreases slightly. For a 90-min electroless plated membrane, the thickness reaches 4.5 μm and the mean pore radius is 0.13 μm with a narrow distribution.

This paper reports the preparation and gas sensitivity properties of Zn 1− x Cd x Fe 2 O 4 to C 2 H 2 OH. Raw powders of Zn 1− x Cd x Fe 2 O 4 were obtained by a chemical co-precipitation and solid-state reaction method. The effects of the calcining temperature on the phase constituents are characterized by X-ray diffraction (XRD). We investigated the influence of CdO on the conductance–temperature correlation, and gas sensing properties of ZnFe 2 O 4 . The results demonstrated that CdO could improve the sensitivity, selectivity and response time of ZnFe 2 O 4 .

The catalytic effect of SmInO 3 , on the conduction and gas-sensing properties of CdIn 2 O 4 was investigated. The results demonstrated that SmInO 3 increases the electrical impedance and improves the sensitivity and selectivity of CdIn 2 O 4 materials to ethanol gas though SmInO 3 based sensors exhibit no sensitivity to reducing gases. The XPS analysis shows that the increase in sensitivity is not related to the increase in the amount of adsorbed oxygen O − (ad) on the material surface. We attribute the sensitivity improvement to the easy adsorption of reducing gas on the surface of SmInO 3 and CdIn 2 O 4 composite and the interfaces between the CdIn 2 O 4 grains and the SmInO 3 grains. The sensors based on CdIn 2 O 4 and SmInO 3 , (molar ratio 3:2) have a high sensitivity and selectivity to ethanol gas and are promising for practical use.

Yttria stabilized zirconia (YSZ) polymeric sols were synthesized by controlled hydrolysis and condensation of zirconium tetra- n -propoxide. Yttrium nitrate was added before hydrolysis as the source of yttria. Acetylacetone was used as chelating ligand to modify the reaction rate of zirconium alkoxide. The dependence of YSZ sol formation as well as gelation time was investigated experimentally on the contents of acetylacetone, n -propanol (solvent) and water for hydrolysis. With a stable sol, YSZ membranes were prepared on porous α-alumina supports by a dip-coating process. The membranes were characterized by scanning electron microscopy and gas permeability testing. Unsupported YSZ membranes were also prepared with the same sol, and were investigated with isothermal nitrogen adsorption/desorption porosimetry and X-ray diffraction. The results show that YSZ membranes with nanosize pores were successfully prepared by the sol–gel technique with the polymeric sols.

This paper reports the preparation and gas-sensing properties of ZnFe 2 O 4 . Raw powders of ZnFe 2 O 4 were obtained by chemical coprecipitation. Effects of the calcining temperature on the phase constituents and microstructure are characterized by TG-DTA and XRD. The conductance-temperature, gas-sensing properties of ZnFe 2 O 4 were investigated. The results demonstrated that ZnFe 2 O 4 can be used as a new type of gas-sensing material which has a high sensitivity and good selectivity to C 2 H 5 OH.

The exhaustion of the major fossil energy sources on earth in near future and the serious environmental pollution from the fuel combustion processes in the presently applied technologies are the most important problems of modern society. The sustainable development of mankind requests strongly to develop “green” power devices characterized by high fuel energy conversion efficiency, less pollution to the environment and convenience to use.

Solid oxide fuel cells (SOFCs) are a promising technology for electric power generation in the 21st century. Recently, research are focusing on reduced temperature SOFCs. The fabrication of thin film electrolytes and electrode membranes for reduced temperatures by a soft chemical route is discussed.

A two layer ultrafiltration alumina membrane was prepared by a sol-gel process using boehmite sol as precursor. The sol was prepared by hydrolysation of aluminium tri-sec-butoxide. Sol properties, such as viscosity as a function of concentration and acidity, were investigated by using capillary viscometry, transmission electron microscopy and laser scattering photometry etc. The viscosity increased with an increase in concentration and a decrease in pH, while the particle shape and size of the sol were mainly determined by pH. The membrane prepared by a dipping procedure was characterized by both scanning electron microscopy and transmission electron microscopy. The results showed that the membrane thickness and surface morphology were affected by the dipping time, the viscosity and the temperature.

A galvanic-cell-type SO x ( x = 2,3) gas sensor with Ag-s″-Al 2 O 3 solid electrolyte, porous Pt as working electrode and Ag as reference electrode has been constructed and tested. The electromotive force (e.m.f.) responses are in good agreement with theoretical values for SO x concentrations from 10 to 10 4 ppm in the temperature range 550–750 °C. The experimental results show that CO 2 and NO 2 did not disturb the measurement of SO x .

A.c. complex impedance measurement has been used in a mixed system of tin oxide and iron oxide in an attempt to obtain more information about the gas-sensitive mechanism of semiconducting metallic oxide gas sensors. The impedance spectra in air, liquid petroleum gas (LPG) and acetylene have been obtained for the thick-film elements at different temperatures. A simple equivalent circuit, which contains the contributions from grain bulks and grain boundaries, is proposed to account for the spectra. The results show that both the grain bulks and grain boundaries of tin oxide (doped with a small amount of antimony oxide) are responsible for the reducing-gas sensitivities. For the iron oxide sample, the grain-boundary resistance is dominant in the total resistance and its change in various atmospheres is the main origin of the sensitivity to reducing gases. For the mixed system, the role of grain boundaries is also found to be more important than that of grain bulks. Some structural analyses and direct-current (d.c.) measurement have also been performed. This preliminary study indicates that a.c. complex impedance measurement might be a powerful tool in studying chemical sensors.

Solid oxide fuel cells (SOFCs) are a promising technology for electric power generation in the 21st century. Recently, research are focusing on reduced temperature SOFCs. The fabrication of thin film electrolytes and electrode membranes for reduced temperatures by a soft chemical route is discussed.

Diamond thin films were produced by microwave plasma chemical vapor deposition. The deposit is identified by x-ray diffraction, Raman spectroscopy and Scanning electron microscopy. During the course of diamond growth, the characteristics of the plasma have been measured by means of the Langmuir double probe and emission spectrometer.

The structures and compositions of oxide sample Bi2Sr2CaGa0.6Co1.4Oy were studied by means of transmission electron microscope and powder x-ray diffractometer. The results show that there are three kinds of oxides in the mixed sample. (1)dominant perovskite structure oxide Bi6Sr2CaCoOy with the cell dimensions a = b =5.51 A , c =29.76 A . (2)body-centered orthorhombic phase BiSr2CaGaCo4Oy with the cell parameters a =6.14 A , b =5.96 A , c =16.30 A . (3) unknown phase. Each of the three oxides has the incommensurate modulation.

The thermal expansion coefficient of single phase superconductor YBa2Cu3O7-δ was measured by the method of differential parallelplate capacitance. An obvious decrease of volume near 205K and a small jump of the thermal expansion coefficient at Tc were observed. The pressure effect was also estimated.

The single (123) phase of Y-Ba-Cu oxides with T-phase structure was prepared using the air-quenching technique. From the measurements of electrical resistance, thermal expansion coefficience, specific heat, ac susceptibility and XRD, it is the first time to find the existance of a structure phase transition. It is suggested to be a structure phase transition from Y-phase to O-phase. The explanation for low Tc in this system is also proposed in this paper.

For the intermediate Y-Ba-Cu-0 (123) samples, from the XRD, resistivity and susceptibility measurement, it can be concluded that the (123) T-phase is non-superconduting till 2.4K and the superconductivity in the intermediate samples is caused by the partly O-phase. For the three samples with pure T-phase, there are phase transitions from T-phase to O-phase with migration of oxygen atoms. The conducting characters are also discussed.

The resistance and thermoelectric power were measured for a series of single phase YBa2 Cu3O7-x samples with different quenching temperature. The relation between the thermopower and temperature indicates that there exists a phonon-drag peak in orthorhombic phase sample. The peak disappears in tetragonal phase sample. This phenomeron suggests that the electron-phonon interaction influences the superconduc tivity of YBa2 Cu3O7-x. According to the experimental data of thermoelectric power, estimation for the Fermi energy and carrier concentration of the sample are made.