Crystal Structure Refinement and Stability of LaFexNi1−xO3Solid Solutions
Crystal Structure Refinement and Stability of LaFexNi1−xO3Solid Solutions
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DOI：
10.1006/jssc.1997.7477
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发表时间：
1997-11
影响因子：
5.4
通讯作者：
H. Falcón;A. Goeta;G. Punte;R. Carbonio
中科院分区：
文献类型：
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作者：
H. Falcón;A. Goeta;G. Punte;R. Carbonio
LaFe{sub x}N{sub 1-x}, O{sub 3} (0 {le} x {le} 1) 固溶体的晶体结构细化通过 X 射线粉末衍射数据的 Rietveld 细化来确定和分析。 0 {le} x < 0.5 的固溶体与 LaNiO{sub 3} 同构，在菱方晶系、空间群 R{bar 3}c 中结晶，而组成 0.5 < x {le} 1 的固溶体与 LaFeO{sub 3} 同构，在斜方晶系、空间群 Pnma 中结晶。所有溶液均为单相，但中间组合物 (x = 0.5) 的溶液除外，其中观察到两相。细胞体积随着铁含量的增加而增加。这可以归因于与 Ni{sup 3+} (LS) 相比，Fe{sup 3+} (HS) 具有更大的离子半径。研究发现，在高达 1000{℃}C 的温度下制备时，LaFe{sub 0.25}Ni{sub 0.75}O{sub 3} 为单相，这表明当用相对少量的铁替代 LaNiO{sub 3} 中的 Ni 时，高温下钙钛矿相的稳定性增加。
The crystal structure refinement of LaFe{sub x}N{sub 1-x}, O{sub 3} (0 {le} x {le} 1) solid solutions was determined and analyzed by means of Rietveld refinement from X-ray powder diffraction data. The solid solutions with 0 {le} x < 0.5 are isostructural with LaNiO{sub 3} and crystallize in the rhombohedral system, space group R{bar 3}c, while those with composition 0.5 < x {le} 1 are isoestructural with LaFeO{sub 3} and crystallize in the orthorhombic system, space group Pnma. All of the solutions are single phase except that with the intermediate composition (x = 0.5), where both phases are observed. The cell volume increases with the iron content. This can be ascribed to the larger ionic radius of Fe{sup 3+} (HS) compared to Ni{sup 3+} (LS). LaFe{sub 0.25}Ni{sub 0.75}O{sub 3} was found to be single phase when prepared at temperatures as high as 1000{degrees}C, indicating an increase in the stability of the perovskite phase at high temperatures when a relatively small amount of iron is substituted for Ni in LaNiO{sub 3}.