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首页> 外文期刊>Acta Crystallographica, Section B. Structural Science >In situ observation of the tetragonal-cubic phase transition in the CeZrO4 solid solution - a high temperature neutron diffraction study
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In situ observation of the tetragonal-cubic phase transition in the CeZrO4 solid solution - a high temperature neutron diffraction study

机译：CeZrO4固溶体中四方立方相变的原位观察-高温中子衍射研究

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摘要

The crystal structure of the compositionally homogeneous ceria-zirconia solid solution CeZrO4 is refined by Rietveld analysis of neutron diffraction data measured in situ over the temperature range 296-1831 K. The CeZrO4 exhibits a tetragonal structure with the space group P4(2)mc at temperatures from 296 to 1542 K (Z = 1), and a cubic fluorite-type form with the space group Fm (3) over barm at 1831 K (Z = 2). The isotropic atomic displacement parameters of Ce and Zr atoms B(Ce,Zr) and O atoms B(O) are found to increase with temperature, with B(O) being larger than B(Ce,Zr), suggesting the higher diffusivity of oxygen ions. The ratio of the c axial length to the a length of the pseudo-fluorite lattice (c/a(F) axial ratio) for the tetragonal CeZrO4 phase increased from 296 to 1034 K and decreased from 1291 to 1542 K, reaching unity between 1542 and 1831 K. The displacement of O atoms along the c axis in the tetragonal CeZrO4 phase increased from 296 to 1034 K and decreased from 1291 to 1542 K, reaching 0.0 angstrom between 1542 and 1831 K. These results indicate that the cubic-to-tetragonal phase transition between 1542 and 1831 K is accompanied by oxygen displacement along the c axis and the increase of the c/a(F) axial ratio from unity.
机译：成分均匀的二氧化铈-氧化锆固溶体CeZrO4的晶体结构通过在温度范围296-1831 K上现场测量的中子衍射数据的Rietveld分析进行精制。CeZrO4呈四方结构，空间群为P4（2）/ nmc在296至1542 K（Z = 1）的温度下，在1831 K（Z = 2）的barm上具有空间群Fm（3）的立方萤石型形式。发现Ce和Zr原子B（Ce，Zr）和O原子B（O）的各向同性原子位移参数随温度增加而增加，其中B（O）大于B（Ce，Zr），表明氧离子。四方CeZrO4相的c轴长度与假萤石晶格长度之比（c / a（F）轴比）从296增加到1034 K，从1291减少到1542 K，在1542之间达到统一四方CeZrO4相中O原子沿c轴的位移从296增加到1034 K，从1291减少到1542 K，在1542和1831 K之间达到0.0埃。这些结果表明立方到在1542和1831 K之间的四方相变伴随着氧气沿c轴的位移和c / a（F）轴向比从一开始的增加。

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