Journal of Solid State Chemistry ( IF 3.3 ) Pub Date : 2017-10-05 , DOI: 10.1016/j.jssc.2017.10.005 S.Ya. Istomin , A.V. Morozov , M.M. Abdullayev , M. Batuk , J. Hadermann , S.M. Kazakov , A.V. Sobolev , I.A. Presniakov , E.V. Antipov
La1−yCayFe0.5+x(Mg,Mo)0.5−xO3-δ oxides with the orthorhombic GdFeO3-type perovskite structure have been synthesized at 1573 K. Transmission electron microscopy study for selected samples shows the coexistence of domains of perovskite phases with ordered and disordered B-cations. Mössbauer spectroscopy studies performed at 300 K and 573 K show that while compositions with low Ca-content (La0.55Ca0.45Fe0.5Mg0.2625Mo0.2375O3-δ and La0.5Ca0.5Fe0.6Mg0.175Mo0.225O3-δ) are nearly oxygen stoichiometric, La0.2Ca0.8Fe0.5Mg0.2625Mo0.2375O3-δ is oxygen deficient with δ ≈ 0.15. Oxides are stable in reducing atmosphere (Ar/H2, 8%) at 1173 K for 12 h. No additional phases have been observed at XRPD patterns of all studied perovskites and Ce1−xGdxO2−x/2 electrolyte mixtures treated at 1173–1373K, while Fe-rich compositions (x≥0.1) react with Zr1−xYxO2−x/2 electrolyte above 1273 K. Dilatometry studies reveal that all samples show rather low thermal expansion coefficients (TECs) in air of 11.4–12.7 ppm K−1. In reducing atmosphere their TECs were found to increase up to 12.1–15.4 ppm K−1 due to chemical expansion effect. High-temperature electrical conductivity measurements in air and Ar/H2 atmosphere show that the highest conductivity is observed for Fe- and Ca-rich compositions. Moderate values of electrical conductivity and TEC together with stability towards chemical interaction with typical SOFC electrolytes make novel Fe-containing perovskites promising electrode materials for symmetrical solid oxide fuel cell.
中文翻译:
(La,Ca)(Fe,Mg,Mo)O3 -δ钙钛矿作为对称SOFC的预期电极材料的高温性能
具有斜方晶系GdFeO 3型钙钛矿结构的La 1-y Ca y Fe 0.5 + x(Mg , Mo)0.5-x O3 -δ氧化物在1573 K上合成。钙钛矿相的结构域与有序和无序的B阳离子。在300 K和573 K下进行的Mössbauer光谱研究表明,虽然Ca含量较低(La 0.55 Ca 0.45 Fe 0.5 Mg 0.2625 Mo 0.2375 O3 -δ和La 0.5 Ca 0.5 Fe 0.6 Mg 0.175 Mo 0.225 O3 -δ)几乎是化学计量的氧,La 0.2 Ca 0.8 Fe 0.5 Mg 0.2625 Mo 0.2375 O3 -δ是氧缺乏的,δ≈0.15。氧化物在还原气氛中(氩/ H稳定2在1173,8%) K中12 小时。在所有研究过的钙钛矿和Ce 1-x Gd x O 2-x / 2电解质混合物中,在1173–1373K处理后,在XRPD模式上均未观察到其他相,而富铁成分(x≥0.1)与Zr 1-x反应ÿ X高于1273 K的O 2-x / 2电解质 。膨胀学研究表明,所有样品在空气中的11.4-12.7 ppm K -1都显示出相当低的热膨胀系数(TECs)。在还原性气氛中,由于化学膨胀作用,其TECs增加至12.1–15.4 ppm K -1。在空气和Ar / H 2气氛中的高温电导率测量结果表明,对于富含Fe和Ca的成分,观察到了最高的电导率。中等的电导率和TEC值以及对与典型SOFC电解质的化学相互作用的稳定性,使得新型含铁钙钛矿有望成为用于对称固体氧化物燃料电池的电极材料。