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Electron diffraction of ABX3 perovskites with both layered ordering of A cations and tilting of BX6 octahedra
Kyosuke Kishida1, Kengo Goto, Haruyuki Inui
1Department of Materials Science and Engineering, Kyoto University, Sakyo-ku, Kyoto, 606-8501, Japan. k.kishida@materials.mbox.media.kyoto-u.ac.jp
Abstract:
It is shown that 21 ABX(3) perovskites with tilted BX(6) octahedra and layered ordering of A cations can be generated on the basis of group-subgroup relations. These structures (with 16 different space groups) are classified into ten diffraction types in terms of the conditions for superstructure reflections caused by the ordering of A cations, tilting of BX(6) octahedra and structural absences. SAED (selected-area electron diffraction) allows the distinction of seven of the 21 different perovskites, while additional symmetry analysis by CBED (convergent-beam electron diffraction) is needed for the remaining 14 structures. The space groups of lithium lanthanum titanate pseudomorphs (with discrete chemical compositions) are successfully deduced by electron diffraction experiments.
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