Materials Physics Laboratory, State Key Laboratory for Mesoscopic Physics, Department of Physics, Peking University, Beijing, People's Republic of China.
J Phys Condens Matter. 2011 Sep 14;23(36):365701. doi: 10.1088/0953-8984/23/36/365701. Epub 2011 Aug 19.
We report a comprehensive x-ray scattering study of the low-temperature orthorhombic (LTO)-high-temperature tetragonal (HTT) structural phase transition in 1% iron-doped La(2-x)Sr(x)CuO(4) (x = 0.2). The superlattice (032) peak intensity and the width are investigated in detail for a wide temperature range. We found that the structural phase transition is not sharp and the tilt ordering of the CuO(6) octahedra persists above the transition temperature T(S) (≈77 K). Even at room temperature, the superlattice peak is still observable. The structural phase transition is identified as an order-disorder type phase transition. We found that the tilt ordering in our iron-doped material is always short-ranged, and in the HTT phase the correlation between the tilts along the b axis is better preserved than that along the a axis. Moreover, we identify the role of the Fe as the nucleation centers of the LTO domains in the structural phase transition.
我们报告了在 1%铁掺杂的 La(2-x)Sr(x)CuO(4)（x = 0.2）中低温正交（LTO）-高温四方（HTT）结构相变的全 X 射线散射研究。我们详细研究了超晶格（032）峰强度和宽度在很宽的温度范围内的变化。我们发现结构相变不是很陡峭，CuO(6)八面体的倾斜有序在相变温度 T(S)（≈77 K）以上仍然存在。即使在室温下，仍然可以观察到超晶格峰。结构相变被确定为有序-无序型相变。我们发现，我们的铁掺杂材料中的倾斜有序总是短程的，并且在 HTT 相中，b 轴方向的倾斜之间的相关性比 a 轴方向的相关性更好地保持。此外，我们确定了 Fe 的作用是结构相变中 LTO 畴的成核中心。
