Abstract

Samples of general formula Ba_0.9Ln_0.1Fe_{1 – y}Co_yO_{3 – δ} (Ln = Nd, Sm, Eu; y = 0.1–0.9) were studied at 1100°С under air. X-ray powder diffraction data for samples prepared by glycerol–nitrate technology were used to determine the homogeneity range of Ba_0.9Ln_0.1Fe_{1 – y}Co_yO_{3 – δ} solid solutions (ss): 0.1 ≤ y ≤ 0.7 for Ln = Nd, 0.1 ≤ y ≤ 0.5 for Ln = Sm, and 0.1 ≤ y ≤ 0.4 for Ln = Eu. The crystal structure of single-phase oxides was described in terms of a cubic unit cell (space group \(Pm\bar {3}m\)). The increasing cobalt content or rare-earth atomic radius brings about an increase in Ba_0.9Ln_0.1Fe_{1 – y}Co_yO_{3 – δ} unit cell parameter. The oxygen content (3 – δ) in the temperature range 25–1100°C under air was determined by thermogravimetry and iodometric titration. Oxygen exchange between the solid oxide and gas phase starts at ~350°С. The oxygen content and mean oxidation state of the 3d metal in Ba_0.9Ln_0.1Fe_{1 – y}Co_yO_{3 – δ} both decrease as the cobalt concentration increases or the lanthanide atomic number increases.

中文翻译：

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Ba0.9Ln0.1Fe1 – yCoyO3 – δ (Ln = Nd, Sm, Eu) 固溶体的晶体结构和氧非化学计量

摘要

通式 Ba _0.9 Ln _0.1 Fe _{1 – y} Co _y O _{3 – δ} (Ln = Nd, Sm, Eu; y = 0.1–0.9) 的样品在 1100°С 的空气中进行了研究。使用甘油-硝酸盐技术制备的样品的 X 射线粉末衍射数据确定 Ba _0.9 Ln _0.1 Fe _{1 – y} Co _y O _{3 – δ}固溶体 (ss) 的均匀性范围：0.1 ≤ y ≤ 0.7 对于 Ln = Nd，对于 Ln = Sm， 0.1 ≤ y ≤ 0.5，并且 0.1 ≤ y对于 Ln = Eu，≤ 0.4。单相氧化物的晶体结构用立方晶胞（空间群\(Pm\bar {3}m\)）来描述。钴含量或稀土原子半径的增加导致 Ba _0.9 Ln _0.1 Fe _{1 – y} Co _y O _{3 – δ}晶胞参数的增加。空气中 25–1100°C 温度范围内的氧含量 (3 – δ) 采用热重法和碘量滴定法测定。固体氧化物和气相之间的氧气交换从约 350°С 开始。Ba _0.9 Ln _0.1 Fe _{1 - y} Co中3d金属的氧含量和平均氧化态 _y O _{3 – δ}都随着钴浓度增加或镧系元素原子序数增加而降低。