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In this study, we utilized the solid-state synthesis method to prepare a Gd2O3-doped cordierite ceramic (0–12.5 wt%). Our objective was to investigate the effects of Gd2O3 doping on various properties, including phase composition, microstructure, sintering characteristics, thermal expansion, mechanical strength, and dielectric properties of cordierite ceramics. Our findings indicated that the introduction of Gd3+ ions had a significant impact on the formation of the cordierite phase, the reduction of spinel impurity, and the growth of grain size, leading to a decrease in the coefficient of thermal expansion. As the amount of Gd2O3 doping increased, the coefficient of thermal expansion decreased from 2.91 × 10–6/°C to 2.15 × 10–6/°C. We achieved the highest flexural strength of 68.54 ± 2.36 MPa in cordierite ceramic doping with 10 wt% Gd2O3 due to optimal densification. Moreover, the quality factor increased from 30,400 GHz to 64,800 GHz, and the dielectric constant ranged from 4.08 to 6.19. [ABSTRACT FROM AUTHOR]

LaBaCo2−xMoxO5+δ (LBCMx, x = 0–0.08) cathodes synthesized by a sol-gel method were evaluated for intermediate-temperature solid oxide fuel cells. The limit of the solid solubility of Mo in LBCMx was lower than 0.08. As the content of Mo increased gradually from 0 to 0.06, the thermal expansion coefficient decreased from 20.87 × 10−6 K−1 to 18.47 × 10−6 K−1. The introduction of Mo could increase the conductivity of LBCMx, which varied from 464 S cm−1 to 621 S cm−1 at 800 °C. The polarization resistance of the optimal cathode LBCM0.04 in air at 800 °C was 0.036 Ω cm2, reduced by a factor of 1.67 when compared with the undoped Mo cathode. The corresponding maximum power density of a single cell based on a YSZ electrolyte improved from 165 mW cm−2 to 248 mW cm−2 at 800 °C. [ABSTRACT FROM AUTHOR]

La0.75Sr0.25Cr0.5Mn0.5O3-δ (LSCM) anodes incorporated with Ag paste (AP) sintered at a relatively low temperature of 900 °C were evaluated. The results of electrochemical impedance spectroscopy displayed that the optimal electrochemical performance was acquired by incorporating 40 wt% Ag paste into the LSCM matrix. The electrical conductivity of LSCM–40AP at 800 °C in air and H2 was 192 S cm−1 and 9.96 S cm−1, respectively. The maximum power density of the cell with LSCM–40AP at 800 °C exhibited a considerable increase by a factor of 1.6, when compared with the cell with pure LSCM. The durability of the single cell with the LSCM–40AP anode was analyzed. The result revealed that the cell voltage slightly reduced from 0.67 to 0.64 V at a constant current density of 0.25 A cm−2 after a 100 h test, indicating good long-term stability of the anode sintered at 900 °C. [ABSTRACT FROM AUTHOR]

In this paper, the relationship between the phase purity, microstructure, conductivity and thermal expansion of the M (Al, Fe, Y and Bi) doped SDC (Ce0.8Sm0.2O1.9) electrolytes was investigated. Ce0.75Sm0.2M0.05O1.875 (M = Al, Fe, Y, Bi) electrolytes were prepared by sol-gel auto-combustion process. From XRD analysis, the dopant ions (Al, Fe, Y and Bi) are doped in the lattice of cubic fluorite structure of SDC and no second phase is formed for Ce0.75Sm0.2M0.05O1.875 (M = Al, Fe, Y, Bi) calcined at 700 °C for 4 h. However, the impurity phase of Ce2O3 is formed for Ce0.75Sm0.2Al0.05O1.875 sintered at 1400 °C for 4 h. Moreover, the relative densities of the samples increase after doped with Fe, Y and Bi. While Al doping cannot improve the sintering performance and decreases the density. These results are consistent with the SEM images. In addition, the grain size of Ce0.75Sm0.2Bi0.05O1.875 is the largest as indicated by SEM microstructure. More importantly, the average thermal expansion coefficient and ionic conductivity of the sintered samples improves after doped with Fe, Y and Bi, which suggests that Ce0.75Sm0.2M0.05O1.875 (M = Al, Fe, Y, Bi) can be a potential electrolyte for the IT-SOFC. [ABSTRACT FROM AUTHOR]

A new design of cathode current-collecting element (CCCE) based on SmSrCoO, which contains gas channels and an array of truncated-pyramid-shaped contact tips, is synthesized through die pressing followed by a conventional solid-state reaction for intermediate-temperature solid oxide fuel cells (IT-SOFCs). This configuration could not only maintain the high electronic conductivity of the material to ensure the efficiency of current collecting, but also improve the gas diffusion rate at the cathode side. The height h of the channel tips on the CCCEs reaches approximately 60, 120, and 240 μm, respectively, which results in the variation in polarization resistance ( R ) more significantly than the contact area of the tips does. The experiments show that the R of the symmetric cells decreased from 0.267 to 0.060 Ω cm at 800 °C after employing the CCCE with modified parameters. In addition, the measured peak power density of the individual cell is enhanced from 111 to 145 mW cm at 800 °C. The results show that the cathode current-collecting elements may be potentially useful for applications in IT-SOFCs. [ABSTRACT FROM AUTHOR]

Composite anodes of La0.75Sr0.25Cr0.5Mn0.5O3−δ –Ce0.8Sm0.2O1.9 (LSCM–SDC) were prepared and investigated as anode materials for intermediate-temperature solid oxide fuel cells (IT-SOFCs) with YSZ electrolyte. Results showed that the addition of SDC significantly enhanced the electrochemical performance of LSCM anode. The anode containing 40 wt.% SDC demonstrated optimal performance. The polarization resistance and anodic overpotential (at a current density of 0.05 A cm−2) of this anode were 0.95 Ω cm2 and 0.12 V in H2 at 800 °C, respectively, whereas those of pure LSCM anode were 3.66 Ω cm2 and 0.38 V, respectively. The electrochemical performance of the LSCM–40SDC composite anode was further improved when a thin SDC interlayer was coated between the anode and YSZ electrolyte. The resulting polarization resistance and anodic overpotential with the SDC interlayer were 0.30 Ω cm2 and 0.035 V in H2 at 800 °C, demonstrating a reduction by factors of 3.2 and 3.4, respectively. The impedance data displayed that the coated SDC interlayer mainly affected the low frequency electrode process, indicating that the SDC interlayer played an important role in the promotion of the dissociation and diffusion processes of H2 oxidation reaction. [ABSTRACT FROM AUTHOR]

Abstract: ZnO doping can significantly diminish the deleterious effect caused by impurities on the grain-boundary conduction of polycrystalline Ce0.8Gd0.2O1.9 electrolyte. Analysis by field emission transmission electron microscopy equipped with energy-dispersive X-ray spectroscopy reveals that the siliceous and ZnO phases are separately aggregated at the triple grain junction areas in ZnO-added specimens. This finding implies that the scavenging process does not occur via the expected formation of zinc silicates, but via a novel mechanism in which resistive siliceous phases strongly aggregate in non-wetting configurations induced by ZnO. A three-dimensional schematic is established to elucidate the role of ZnO in the CeO2–Gd2O3 system. [Copyright &y& Elsevier]

Abstract: The effects of B2O3–Bi2O3–PbO (BBP) frit on the electrochemical performance, electrical conductivity, and thermal expansion of LaBaCo2O5+δ (LBCO) cathode were investigated. BBP frit was found to be effective in lowering the sintering temperature of LBCO cathode by about 200 °C and in improving its electrochemical performance within the intermediate-temperature range of 600–800 °C. LBCO with 5 wt.% BBP frit cathode based on Sm0.2Ce0.8O1.9 electrolyte showed the best electrochemical performance, i.e., the lowest area-specific resistance (ASR) and cathodic overpotential. The ASR values were about 64.1%, 66.1%, and 74.5% lower than those of LBCO at 700, 750, and 800 °C, respectively. The cathodic overpotential decreased from 51.0 mV for LBCO to 8.2 mV at a current density of 0.2 A cm−2 at 700 °C. The electrical conductivity of LBCO with 5 wt.% BBP frit was about 320–330 S cm−1 at 600–800 °C in air. [Copyright &y& Elsevier]

The LaBaCo2O5+δ−x wt.% Bi2O3 (LBCO-xBi2O3, x=10, 20, 30, and 40) were prepared as composite cathodes for intermediate-temperature solid oxide fuel cells (IT-SOFCs) via the conventional mechanical mixing method. The effect of Bi2O3 on polarization resistance, overpotential, and long-term stability of the LBCO cathode was investigated. An effective sintering aid for LBCO cathode, Bi2O3 not only lowers its sintering temperature by ~200°C, but also improves the electrochemical performance within the intermediate temperature range of 600–800°C. Electrochemical impedance spectroscopy measurements showed that the addition of 20wt% Bi2O3 to LBCO exhibited the lowest area-specific resistance of 0.020Ωcm2 at 800°C in air, which was about a seventh of that of the LBCO cathode at the same condition. At a current density of 0.2Acm−2, the cathodic overpotential of LBCO-20Bi2O3 was about 12.6mV at 700°C, while the corresponding value for LBCO was 51.0mV. Compared to B2O3–Bi2O3–PbO frit, the addition of Bi2O3 significantly improved the long-term stability of cathode. Therefore, LBCO-20Bi2O3 can be a promising cathode for IT-SOFCs. [ABSTRACT FROM AUTHOR]

Ca3Co2O6 (CCO) is synthesized by solid state reaction for intermediate temperature solid oxide fuel cells (IT-SOFCs) on yttria-stabilized zirconia (YSZ) electrolyte. Thermal expansion coefficient (TEC), electrical conductivity (σ) and chemical compatibility of CCO with YSZ are characterized. The experiment results show that CCO and YSZ are chemical compatible only up to 800 °C. By introducing a Sm0.2Ce0.8O1.9 (SDC) interlayer to avoid the direct contact of CCO with YSZ, the area specific resistance (ASR) of CCO cathode is significantly decreased from 13.06 Ω cm2 to 0.60 Ω cm2 at 750 °C. Furthermore, the addition of frit can lower the sintering temperature of the cathode to ∼800 °C, also resulting in a remarkable decreasing of the ASR to 3.87 Ω cm2 at 750 °C. [ABSTRACT FROM AUTHOR]