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Disorder-order phase transition induced by size effect in bulk La2/3Sr1/3MnO3 |
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| Authors: | BZ Sun LL He F Luo |
| Institution: | a College of Science, Northeastern University, Shenyang 110004, China b Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016, China c State Key Laboratory of Rare Earth Materials Chemistry and Applications, PKU-HKU Joint Laboratory in Rare Earth Materials and Bio-inorganic Chemistry, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China |
| Abstract: | Bulk La2/3Sr1/3MnO3 ceramic samples prepared by thermal decomposition are investigated using transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM). An abnormal phenomenon, where three kinds of La2/3Sr1/3MnO3 phases with different structures and the same composition coexist in the same grain, has been observed. Besides the stable rhombohedral majority phase, the two other phases are a simple cubic structure with a=0.389 nm and a new hexagonal structure with a=0.544 nm, c=0.668 nm. The simple cubic phase is a residual phase of high-temperature due to the size effect and bondage of twin boundary. Image simulations have suggested that the new hexagonal phase is the La-Sr ordered structure with space group  , which is converted from the disordered simple cubic phase. The formation mechanism of the ordered phase is explained from volume energy and interface energy considerations. |
| Keywords: | 64 60 Cr 68 37 Lp |
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