Translation and orientation domain boundaries in La_2/3Ca_1/3MnO₃

Abstract

From crystal structure, three types of translation and two types of orientation domain boundaries are expected in La_2/3Ca_1/3MnO₃ as a result of phase transition. However, the most easily observed domain boundaries in the bulk samples are translation boundaries (or antiphase boundaries) and 90° domain boundaries, while the and translation boundaries were rarely observed. In this paper, this phenomenon is explained by considering the tilting modes of the oxygen octahedra in the structure. We found that there is no distortion to the nearby oxygen octahedra if the translation boundaries take the (010) boundary planes and the 90° domain boundaries are in the {101} planes, making them low-energy boundary planes and, thus, are easy to form. On the other hand, the and translation boundaries introduce a distortion in the oxygen octahedra, which requires breaking the tilting modes in the boundary areas and, therefore, they are high-energy boundary planes, which are rarely observed. The above-expected results are supported by our transmission electron microscopy data.

Acknowledgements

The authors would like to thank Dr Q. Y. Xu for preparation of polycrystalline La_2/3Ca_1/3MnO₃ samples and Dr C. L. Jia, Dr S. B. Mi and Professor Dr K. Urban for fruitful discussion and modification of the manuscript. This work is supported by Forschungszentrum Jülich.