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The effect of a small addition of MoO3 on the microstructure and ionic conductivity of Nd0.2Ce0.8O1.9 (NDC), La0.8Sr0.2Ga0.8Mg0.2O2.8 (LSGM) and Nd0.2Ce0.8O1.9-La0.8Sr0.2Ga0.8Mg0.2O2.8 (NDC-LSGM) has been investigated. The microstructure and electrical properties of the samples were characterized by X-ray diffraction, field-emission scanning electron microscopy and electrochemical impedance spectroscopy. The results show that MoO3 doping can obviously increase the densification and grain sizes, and decrease the grain and grain boundary resistances of the NDC, LSGM and NDC-LSGM electrolytes. It expands the oxygen ion channels and reduces the total conductance activation energy of the system. The total conductivities of MoO3-doped NDC and NDC-LSGM samples are 1.56 and 2.10 times higher than that of the undoped NDC system at 450°C. The total conductivity of LSGM-Mo is 1.46 times higher than that of LSGM at 450°C. These finding suggest that MoO3 is considered to be an effective sintering aid that optimizes the electrical properties of NDC, LSGM and NDC-LSGM electrolytes. [ABSTRACT FROM AUTHOR]

Abstract: The effects of MoO3 concentration on the sintering and electrical properties of Ce0.8Nd0.2O1.9 + 500 ppm SiO2 (NDCSi) and (Ce0.8Nd0.2O1.9)1 − x (MoO3) x  + 500 ppm SiO2 ( x = 0.01, 0.02, 0.03, 0.04, 0.05, NDCSi + 1MoO3, NDCSi + 2MoO3, NDCSi + 3MoO3, NDCSi + 4MoO3, NDCSi + 5MoO3) prepared through a modified sol–gel method were systematically investigated. The structures and ionic conductivities were characterized by XRD, FE-SEM and EIS. The results indicated a sharp increase in densification and conductivity for the system of NDCSi containing small amount of MoO3. It shows that NDCSi + 3MoO3 exhibited much higher relative density (RD = 96%), higher conductivity (σ t = 1.25 × 10−2 S cm−1 at 600 °C) and lower activation energy (E a = 0.81 eV) compared with NDCSi and the other MoO3 doped-NDCSi samples. Furthermore, MoO3 could be used as an effective sintering aid and a grain boundary scavenger for NDCSi system. And we obtained the optimal amount of the MoO3 is 3 mol%. [Copyright &y& Elsevier]

We demonstrate the utilization of bismuth tungstate (Bi 2 WO 6 , BW) as a sintering aid and reinforcement component into neodymium-doped ceria (Nd 0.2 Ce 0.8 O 3-δ , NDC) to fabricate bismuth tungstate/neodymium-doped ceria composite electrolyte for intermediate-temperature solid oxide fuel cells (IT-SOFC). The presence of BW lowers the sintering temperature of NDC electrolyte to 1000 °C. Moreover, at 600 °C, the electrical conductivity of 5 mol.% BW-incorporated NDC (5BW-NDC) composite electrolyte is 7.12 times higher than the NDC. It is worth mentioning that the enhanced electrical conductivity of 5BW-NDC composite electrolyte does not include the contribution from electronic conductivity. Furthermore, NDC and 5BW-NDC exhibit excellent compatibility with La 0.6 Sr 0.4 Co 0.8 Fe 0.2 O 3-δ cathode and NiO anode in terms of thermal expansion coefficient and chemical reactivity. The oxygen reduction reaction at 5BW-NDC composite electrolyte/cathode interface is significantly enhanced by ∼40% compared to NDC. Moreover, 5BW-NDC electrolyte-supported SOFC delivers a power density of 0.86 W cm−2 at 700 °C, which is 45.76% higher than the NDC-based SOFC. The output performance remains stable during high-temperature operation for 120 h, which indicates the stability and chemical compatibility of the as-synthesized composite electrolyte with other cell components. The results reveal that BW-NDC composite is a potential electrolyte material for stable and high-performance IT-SOFCs. • A novel BW-NDC composite ceramics is developed to act as electrolyte of SOFCs. • BW-NDC ceramics is densified at 1000 °C due to BW played the role of sintering aid. • BW-NDC exhibits 7.27 times higher ionic conductivity than that of NDC. • ∼40% improvement of oxygen reduction reaction and power density with BW-NDC ceramics. [ABSTRACT FROM AUTHOR]

In order to optimize the electrical properties of co-doped ceria electrolytes, Ce 0.8 Ca 0.15 Sm 0.05 O 2− δ (CCS) sintered at different temperatures (1150 °C, 1200 °C, 1250 °C, 1300 °C and 1350 °C for 8 h) have been prepared and systematically investigated. It is found that among these samples sintered at different conditions, the electrical conductivity ( σ ) measured at 800 °C can be ranked as: CCS 1250 °C : σ CCS 1250 ° C 800 ° C = 2.38 × 10 −2 S cm −1 > CCS 1200 °C : σ CCS 1200 ° C 800 ° C = 1.81 × 10 −2 S cm −1 > CCS 1150 °C : σ CCS 1150 ° C 800 ° C = 1.50 × 10 −2 S cm −1 > CCS 1300 °C : σ CCS 1300 ° C 800 ° C = 1.26 × 10 −2 S cm −1 > CCS 1350 °C : σ CCS 1350 ° C 800 ° C = 0.68 × 10 −2 S cm −1 . The electrical conductivity of CCS increases with the increase of sintering temperatures, and the 1250 °C-sintered sample presents the highest conductivity because of the best microstructures. However, the electrical conductivity of CCS decreases when the sintering temperatures goes beyond 1250 °C. We attribute this to the phase instability. It reveals that microstructures and the phase stability have important effects on the optimization of electrical properties for the co-doped ceria electrolytes. [ABSTRACT FROM AUTHOR]

Abstract: In order to optimize the electrical properties of co-doped ceria electrolytes, Ce0.8Ca0.15Sm0.05O2−δ (CCS) sintered at different temperatures (1150 °C, 1200 °C, 1250 °C, 1300 °C and 1350 °C for 8 h) have been prepared and systematically investigated. It is found that among these samples sintered at different conditions, the electrical conductivity (σ) measured at 800 °C can be ranked as: CCS1250 °C:  = 2.38 × 10−2 S cm−1 > CCS1200 °C:  = 1.81 × 10−2 S cm−1 > CCS1150 °C:  = 1.50 × 10−2 S cm−1 > CCS1300 °C:  = 1.26 × 10−2 S cm−1 > CCS1350 °C:  = 0.68 × 10−2 S cm−1. The electrical conductivity of CCS increases with the increase of sintering temperatures, and the 1250 °C-sintered sample presents the highest conductivity because of the best microstructures. However, the electrical conductivity of CCS decreases when the sintering temperatures goes beyond 1250 °C. We attribute this to the phase instability. It reveals that microstructures and the phase stability have important effects on the optimization of electrical properties for the co-doped ceria electrolytes. [Copyright &y& Elsevier]