High-Pressure and Temperature Syntheses and Structural Stability Studies of Some Rare-Earth Oxides
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摘要: 首次用高压高温方法，在3.2~4.0 GPa，1 000~1 300 ℃下，对CeO2-R2O3（R=Eu，Gd），CeO2-Tb4O11，Pr6O11-Tb4O7稀土氧化物进行合成实验，得到具有F型结构的CeEuO3.5，CeGdO3.5，CeTbO3.5；B型结构的CeEuO3，CeGdO3，CeTbO3，PrTbO3和P型结构的PrTbO3。PrTbO3是迄今自然界尚未发现，文献未见报导过的新物质。对上面的产物和NdYbO3、PrTmO3，利用高、低温X射线衍射实验，检测了其结构的稳定性，结果指出：从300 ℃直到1 000 ℃，发生由B型CeROx向F型CeROx（R=Eu，Gd，Tb）、B型PrTbO3向C型PrTbO3的结构转变。F型CeROx属于氧缺位萤石型结构。
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关键词:
- 稀土氧化物 /
- 高压高温合成 /
- 结构稳定性 /
- 高 /
- 低温X射线粉末衍射法
Abstract: By using high pressure and temperature method for the first time and under the conditions of 3.2~4.0 GPa, 1 000~1 300 ℃, the synthetic experiments for the rare earth oxide systems of CeO2-R2O3 (R=Eu, Gd), CeO2-Tb4O11, Pr6O11-Tb4O7 were made, and the products of F-CeEuO3.5, -CeGdO3.5, -CeTbO3.5; B-CeEuO3, -CeGdO3, -CeTbO3 and B-PrTbO3, P-PrTbO3 were obtained. The PrTbO3 is a new material which has not been discovered in natural world up to date. The structural stability of the above products and NdYbO3, PrTmO3 has been measured by using high and low temperature X-ray powder diffraction method. The results indicated that some structural transformations from B-CeROx to F-CeROx (R=Eu, Gd, Tb) and from B-PrTbO3 to C-PrTbO3 occur at the temperature going from 300 ℃ to 1 000 ℃. The F-CeROx belongs to a fluorite-type structure with oxygen deficiency. -
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