Preparation and characterization of YBaCo4–y Cu y O7 + x compounds
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- 作者：L. P. Kozeeva ; M. Yu. Kameneva ; V. Yu. Komarov ; A. N. Lavrov…
- 关键词：cobaltates ; phase formation ; solid solutions
- 刊名：Inorganic Materials
- 出版年：2016
- 出版时间：October 2016
- 年：2016
- 卷：52
- 期：10
- 页码：1045-1050
- 全文大小：1,013 KB
- 刊物类别：Chemistry and Materials Science
- 刊物主题：Chemistry
Inorganic Chemistry
Industrial Chemistry and Chemical Engineering
Materials Science
Russian Library of Science - 出版者：MAIK Nauka/Interperiodica distributed exclusively by Springer Science+Business Media LLC.
- ISSN：1608-3172
- 卷排序：52
文摘
Phase formation processes along the YBa(Co, Cu)4O7 + x section of the Y–Ba–Co–Cu–O system have been studied in the temperature range 900–1150°C under atmospheric oxygen pressure. We have located the boundaries of the homogeneity range of the YBaCo4–yCuyO7 + x (114) phase and determined the temperature- dependent copper solubility in this phase, ymax(t) (ymax ≈ 0 at 900°C; the highest solubility is ymax ≈ 0.7, at t = 1000–1050°C). Using X-ray diffraction data for quenched samples, we have identified the phases that coexist with YBaCo4–yCuyO7 + x in the phase regions adjacent to its homogeneity range. The results demonstrate that, if the percentage of copper in a starting mixture, y0, exceeds the copper solubility limit in the 114 phase at a given synthesis temperature, the excess copper concentrates in copper-rich phases: YBaCo2–yCuyO5 + x (112), Co1–yCuyO1 + x (001), and Y2Cu2O5 + x (202). At temperatures in the range 900 ≤ t ≤ 1050°C and compositions in the range y0 ≤ 0.9, the system can be thought of as ternary, with a constant Y: Ba ratio of 1: 1 (that is, only the 114, 112, and 001 phases are present at equilibrium). Beyond this region, phases with other Y: Ba ratios appear.