Strain induced coexistence of monoclinic and charge ordered phases in La1-xCaxMnO3

被引：41
作者：
Sagdeo, P. R. [1 ]
Anwar, Shahid [1 ]
Lalla, N. P. [1 ]
机构：
[1] UGC, DAE, Consortium Sci Res, Indore 452017, India
来源：
PHYSICAL REVIEW B | 2006年 / 74卷 / 21期
关键词：
D O I：
10.1103/PhysRevB.74.214118
中图分类号：
T [工业技术];
学科分类号：
08 ;
摘要：
Coexistence of charge- ordered (CO) and monoclinic (M) phases has been investigated in La1-xCaxMnO3 (x = 0.6, 0.67, and 0.7). For this purpose, pellets and their corresponding powdered samples have been studied employing low-temperature powder x-ray diffraction down to 87 K and transmission electron microscopy down to 109 K. Diffraction studies have revealed that the coexistence of M and CO phases occurs only in pellet samples and not in the powdered versions of the same samples. The powders, which have exactly the same composition as their corresponding pellets, show only CO phases. The observed coexistence of M and CO phases in pellets is not due to compositional inhomogeneity within the grain but due to the presence of intrinsic strain in the pellets that is being imposed by the grain boundary network on the grains of the Pnma phase. The occurrence of monoclinic phase has been attributed to the possible softening of C-44 elastic modulus of the pseudocubic phase.
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