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The nanocrystalline compounds of Co and Cu co-doped ceria (with up to 20 mol% of dopants) were fabricated by the reverse microemulsion synthesis method. They were deposited in a form of layers on the surface of SOFC anode in an aim to act as electrochemically active materials for biogas reforming process. Fourier Transformed Infrared Spectroscopy was used to analyze a composition of outlet gases simultaneously with the tests of electrical parameters of a fuel cell. It allowed comparing a catalytic activity of fabricated materials towards internal biogas reforming. It was found that Cu and Co ceria co-doping improves electrical parameters of a fuel cell and enhances its long-term stability when compared with mono-doped ceria. This type of a material gives also the highest conversion rate of methane and the highest yield of carbon monoxide.

The topography, microstructure, and electrical properties of strontium–borate glass and SBO glass containing bismuth and vanadium oxides, were studied. The structure was measured using X-ray diffraction (XRD), energy dispersive X-ray spectrometer (EDS), and scanning electron microscope (SEM) methods. The A.C. complex conductivity was investigated as a function of temperature and frequency. The influence of the quantity of bismuth and vanadium oxides present, on glasses microstructure and electrical properties, was discussed. In order to obtain glass-ceramics, the glasses were subjected to crystallization at temperatures close to the exothermic processes indicated by the differential scanning calorimetry (DSC) measurements. X-ray diffraction (XRD) measurements were carried out to determine the presence of bismuth vanadate (Bi 2 VO 5.5 ) crystalline phase in heat-treated samples. After heat treatment, there were still some traces of the glassy phase within the samples. The effect of the crystallization process on the microstructure, topography, and dielectric behavior of the material was analyzed. The A.C. dielectric permittivity, conductivity, and impedance were discussed at specific temperature and frequency region; in addition, conduction mechanisms were proposed.

In this paper solid oxide fuel cells operating with dry synthetic biogas have been examined. In order to increase their stability the layers of CuO-CeO 2 , Cu 1.3 Mn 1.7 O 4 and Y 0.08 Sr 0.92 Ti 0.8 Fe 0.2 O 3 -δ have been deposited on the Ni-YSZ anode site. These layers should catalyze the internal biogas reforming and prevent the carbon deposition on the anode site. It has been found that CuO-CeO 2 and Cu 1.3 Mn 1.7 O 4 catalysts led to an increase of the stability (at least 7 days) of the fabricated fuel cells powered by biogas, whereas the unmodified fuel cell, as well as the fuel cell with Y 0.08 Sr 0.92 Ti 0.8 Fe 0.2 O 3 -δ catalyst degraded gradually with time. A significant amount of carbon nanofibers has been formed on the catalyst surface after fuel cell test. However, they have not formed in the anode area. The use of CuO-CeO 2 and Cu 1.3 Mn 1.7 O 4 catalysts prevented the carbon deposition on the anode site, and thus the fuel cell degradation was slower when operating with biogas fuel.

The nonlinear and linear electrical properties, topography, and microstructure of bismuth-vanadate ceramics, were studied. The structure was observed with the use of X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM) and confocal microscopy methods. The obtained results showed that ceramic is porous. Two phase transitions were determined with the use of DSC measurements. The linear and nonlinear ac complex conductivity was studied as the function of frequency, temperature, and ac voltage. The activation energy of dc conduction processes was evaluated. The temperature dependence of conductance and permittivity showed a specific behaviour in two temperatures which were in agreement with phase transition temperatures. The nonlinear impedance studies showed that the ratio of third harmonic to base frequency conductivity reached more than 0.20. Obtained nonlinearities achieved two maxima near phase transition temperatures.

The ac and dc conductivity in iron–lead-borate glass samples was investigated in the frequency range from 1 mHz to 1 MHz and in the temperature range from 153 K to 423 K. The structure was investigated by the means of atomic force microscopy (AFM) and the crystalline phases (if present) were identified by the means of X-ray diffractometry. Two types of ac electrical behaviour were observed. The first group of glass samples which contain up to 31% mol Fe 2 O 3 shows singular flattened semicircle in the impedance spectra. The second group of glass with over 25% mol Fe 2 O 3 shows two distinguishable semicircles indicating two relaxation processes. The results of structure investigation show that glass samples containing more than 2.5% mol Fe2O3 contain ball-shaped nanostructures. They have average size of an order of magnitude 100 nm. In XRD patterns for glass containing less than 19% mol Fe2O3 there are no diffraction peaks while in the patterns for samples with a larger amount of iron oxide some small peaks are present which indicate that some crystalline phases exist in these samples. In glass containing up to 19% iron oxide one process is responsible for conduction mechanism, small-polaron hopping. In the glass samples containing more of iron oxide, two dielectric relaxation processes were found. The second process may be caused by interface effect or conductivity process in the granules.

The linear impedance spectra of iron–silicate–lead glass samples were measured in the frequency range from 1 MHz to 1 MHz and in the temperature range from 153 K to 423 K. The structure was investigated by means of XRD and atomic force microscopy. Local electrical and magnetic properties of the samples were tested with the aid of electrostatic force microscopy (EFM) and magnetic force microscopy (MFM). The obtained results show that the impedance spectra of all samples exhibit one large relaxation process and some additional small relaxation is present in glass containing 20 mol% and 25 mol% Fe2O3. The AFM micrographs show that in a subset of samples some nanostructures exist. Their size, shape, and quantity depend on the amount of Fe2O3 in the composition of the glass. The samples containing an amount of 15 mol% of Fe2O3 include the biggest nanostructures which are ball-shaped. EFM and MFM micrographs show that nanostructures exhibit different electrical and magnetic behaviors than the rest of the glass matrix. On the basis of Jonscher universal dielectric response the temperature dependence of conductivity exponent s was determined and compared to theoretical models proposed by Elliott. It was found that while in the glass containing less than 15 mol% iron oxide, there is only one process responsible for conduction mechanism, the overlap polaron tunneling. In the other samples, a different conduction mechanism may coexist: quantum mechanical tunneling between semiconducting granules.

Solid oxide fuel cells (SOFCs) are one of the most promising energy conversion devices due to their high efficiency, low pollution and fuel flexibility. Unfortunately, when hydrocarbons are used as a fuel, for example in the form of a biogas, solid carbon can deposit on the anode surface. This process leads to the degradation of the fuel cell performance. A possible solution to this problem is to apply an additional catalytic material, which would improve catalytic activity towards the direct internal reforming of the biogas. In this work three catalytic materials were investigated towards the biogas reforming: Cu 1.3 Mn 1.7 O 4 , Y 0.08 Sr 0.92 Ti 0.8 Fe 0.2 O 3 − δ and CeCu 2 O 4 . Materials were infiltrated into the Ni/YSZ cermet and YSZ structure. Their catalytic activities were tested in a synthetic biogas (mixture of 60% of methane and 40% of carbon dioxide) using FTIR spectroscopy of the outlet gases. Infiltration with catalytic materials improved the catalytic properties of supports, however, did not reduce the carbon formation rate.

Nonstoichiometric Nb-substituted SrTiO3 compounds were investigated in order to discuss the influence of nonstoichiometry at the sample properties in the light of recent results reported in the literature. Structural and electrical properties of samples were characterized. Investigated compounds were also applied as anodes for Solid Oxide Fuel Cells and their reactivity with YSZ electrolyte was examined. The defect chemistry explaining observed phenomena was suggested and the probability of Sr-site vacancies formation compared to Ti-site vacancies was discussed.

The presented research concerns acceptor doped barium cerate and the attempts of improvement of its production method that would allow obtaining the solid electrolyte characterized by the particular properties. The authors suggest combining two production methods, molten salt synthesis and self-combustion, in order to achieve the compound material that has some of the advantages of both of the initial methods. An impact of nickel addition on the phase purity, morphology, density and conductivity of the sample was also studied. The results of the investigation appeared to be very promising, as the resulting sample meets the requirements typical for proton conductors.

Niobium-doped strontium titanate was used as the anode for a solid oxide fuel cell. Electrolyte-supported cells were prepared with pure perovskite and composite perovskite–yttria–stabilized-zirconia (YSZ) anodes. Fuel cell tests demonstrated significant improvement in power density after infiltration with a small amount of Ni. The obtained values of power densities are comparable with conventional Ni/YSZ cermet anode. In addition, stability tests showed initial degradation followed by stable operation.

Metal-supported solid oxide fuel cells are regarded as a new generation of SOFC devices. The use of porous metal substrate provides a high mechanical strength of a SOFCs' support and lowers the cost of fuel cells. In this study, powders of PI600, 317L and 430L steel grades were used to prepare porous metallic supports. After sintering at different temperatures, their porosity and high temperature corrosion resistance were evaluated. Cyclic thermogravimetric analysis, X-ray diffractometry and SEM imaging were used to describe properties of these porous alloys. Electrical properties were studied for selected samples. The influence of porosity on resulting properties was elucidated. The porosity changes measured between oxidation cycles were presented. Results showed that the properties of porous alloys differ significantly from those of dense ones. The high temperature corrosion rate is high and is strongly influenced by the porosity level. Open porosity decreases rapidly upon oxidation at 800 °C. As an outcome of this study, the PI600 alloy performs best among those investigated; however, better corrosion resistant materials are needed for SOFCs' supports operating at 800 °C.

The results of a.c. electrical conductivity measurements in (Bi,Pb)–Sr–Ca–Cu–O glasses were reported. Two components of total conductivity were observed. Activation energies of both processes were determined. The small polaron hopping between copper ions in a different valency state Cu I –Cu II is one process. We propose that the second is ionic conductivity caused by Cu I ions.