Phase Equilibria in Systems Involving the Rare-Earth Oxides. Part I. Polymorphism of the Oxides of the Trivalent Rare-Earth Ions
Phase Equilibria in Systems Involving the Rare-Earth Oxides. Part I. Polymorphism of the Oxides of the Trivalent Rare-Earth Ions
复制标题
涉及稀土氧化物的系统中的相平衡。
DOI：
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发表时间：
1960
期刊：
影响因子：
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通讯作者：
S. Schneider
中科院分区：
文献类型：
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作者：
R. Roth;S. Schneider
用X-射线衍射方法对纯稀土氧化物的多晶型关系进行了重新研究。三价稀土离子的氧化物以三种不同的类型结晶：A、B和C。每种氧化物只有一种真正稳定的多晶型：La 2 O3、Ce 2 O3、Pr 2 O3和Nd 2 O3属于A型; Sm 2 O3、Eu 2 O3和Gd 2 O3属于B型; Tb 2 O3、Dy 2 O3、Ho 2 O3、Er 2 O3、Tm 2 O3、Yb 2 O3和Lu 2 O3属于C型。此外，Nd 2 O3、Sm 2 O3、Eu 2 O3和Gd 2 O3具有低温、明显亚稳的C型多晶型物。随着温度的升高，阳离子半径逐渐减小，低温形式不可逆地转化为稳定形式。
The polymorphic relationships of the pure rare-earth oxides have been reinvestigated using X-ray diffraction methods for identification of phases. The oxides of the trivalent rare earth ions crystallize in three different types: A, B, and C. Each oxide has only one truly stable polymorph: La2O3, Ce2O3, Pr2O3, and Nd2O3 belong to the A type; Sm2O3, Eu2O3, and Gd2O3 to the B type; Tb2O3, Dy2O3, Ho2O3, Er2O3, Tm2O3, Yb2O3, and Lu2O3 to the C type. In addition Nd2O3, Sm2O3, Eu2O3, and Gd2O3 have low-temperature, apparently metastable, C-type polymorphs. The low-temperature form inverts irreversibly to the stable form at increasingly higher temperatures for decreasing cation radius.