We have studied the crystal structure of the misfit-layered crystal Bi 1.91Sr2Rh1.77Ox by electron diffraction and high-resolution electron microscopy. This compound consists of two interpenetrating subsystems of a RhO2 sheet and a distorted four-layered rock-salt-type (Bi,Sr)O block. Both subsystems have common a-axes, c-axes, and β-angles with a = 5.28 Å, c = 29.77 Å, and β = 93.7°. On the other hand, the crystal structure is incommensurated parallel to the b-axis, b1 = 3.07 Å for the RhO2 sheet and b 2=4.88 Å for the (Bi,Sr)O block. The axis ratio, b1/b2∼0.63, characterizes the structural analogue as [Bi 1.79Sr1.98Oy]0.63[RhO2]. This compound has two modulation vectors, q1 = a* + 0.63b 1* and q2 = 0.17b1* + c*, and the superspace group is assigned as the Cc(1 β0, 0μ1) type from electron diffraction patterns. High-resolution images taken with the incident electron beam parallel to the a- and c-axes clearly exhibit modulated displacive as well as compositional atomic arrangements. A tentative structure model has been proposed, and the calculated image reproduces observed characteristic features reasonably well.
|ジャーナル||Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers|
|出版ステータス||Published - 2005 12月 8|
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