Abstract

The conductivity of perovskites La_0.3Ca_0.7Fe_0.6Mg_0.175Mo_0.225O_3 – δ (LCF6) and La_0.3Ca_0.7Fe_0.5Mg_0.25Mo_0.25O_3 – δ (LCF5) is studied in the temperature interval of 573–1173 К at varied oxygen partial pressure. It is found that when going from air to the reductive atmosphere (8% Ar/H₂), the conductivity of both samples at 1173 K increases from 4.6 to 25 S/cm for LCF6 and from 0.5 to 10 S/cm for LCF5. For LCF5, the conductivity is shown to be virtually independent of the oxygen partial pressure throughout the studied intervals of temperature and partial pressure, whereas for LCF6 two regions are observed. The conductivity of LCF5 remains constant at the cyclic change of the atmosphere from air to the reductive atmosphere and back. The method of impedance spectroscopy is used for studying the electrochemical behavior in air of the porous electrode based on (La,Ca)(Fe,Mg,Mo)O_{3 – δ} deposited on the solid electrolyte of Ce_0.8Gd_0.2O_1.9 (GDC). The polarization resistance of the electrode/electrolyte interface (R_η) is found to be 2.7 and 3.6 Ω cm² for electrodes of LCF5 and LCF6, respectively, at 1173 K. The partial substitution of Co for Fe allows the R_η value of La_0.3Ca_0.7Fe_0.45Co_0.05Mg_0.25Mo_0.25O_3 – δ and La_0.3Ca_0.7Fe_0.55Co_0.05Mg_0.175Mo_0.225O_3 – δ to be decreased to ∼1.2 Ω cm². Moreover, these materials demonstrate the CTE values close to that of GDC and also exhibit the acceptable conductivity in both air and reductive atmosphere and, hence, can be recommended for using as the electrode material in symmetrical solid-oxide fuel cells.

中文翻译：

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基于钙钛矿（La，Ca）（Fe，Co，Mg，Mo）O 3-δ的对称固体氧化物燃料电池的新型电极材料

摘要

研究了钙钛矿La _0.3 Ca _0.7 Fe _0.6 Mg _0.175 Mo _0.225 O _3-δ（LCF6）和La _0.3 Ca _0.7 Fe _0.5 Mg _0.25 Mo _0.25 O _3-δ（LCF5）的电导率。在不同的氧气分压下。发现从空气进入还原性气氛（8％Ar / H ₂），两个样品在1173 K时的电导率对于LCF6从4.6增加到25 S / cm，对于LCF5从0.5到10 S / cm。对于LCF5，在整个研究的温度和分压间隔内，电导率实际上都与氧分压无关，而对于LCF6，则观察到两个区域。LCF5的电导率在大气从空气到还原性大气再到大气的循环变化中保持恒定。阻抗谱法用于研究沉积在Ce _0.8 Gd _0.2 O _1.9（GDC）固体电解质上的基于（La，Ca）（Fe，Mg，Mo）O _3-δ的多孔电极在空气中的电化学行为。）。电极/电解质界面的极化电阻（ř _η）被发现是2.7和3.6Ω厘米²分别LCF5和LCF6，电极，在1173 K.的Co为铁的部分替代允许ř _η La中值_0.3钙_0.7铁_0.45钴_0.05的Mg _0.25沫_0.25 O _3-δ和La _0.3 Ca _0.7 Fe _0.55 Co _0.05 Mg _0.175 Mo _0.225 O _3-δ降低至〜1.2Ωcm ²。此外，这些材料证明其CTE值接近GDC的CTE值，并且在空气和还原性气氛中均显示出可接受的电导率，因此，可推荐用作对称固体氧化物燃料电池的电极材料。