Abstract：
A domain-resolved synchrotron single-crystal X-ray diffraction study of a LaAlO3 pseudo-merohedral twin crystal was successfully carried out in combination with powder diffraction data from the same sample. Multiscale structure information ranging from micro- to nano- to atomic scale was determined from one single crystal. There is almost no change of domain ratios at temperatures of less than 400 K indicating no movement of the domain wall. The changes in domain ratio indicating domain-wall movement were observed in the temperature range of 450 to 700 K, which is consistent with the result of the previous mechanical measurement. It is also found that the ratio of four twin components becomes equal (25%), just below phase transition temperature. These findings are important for domain engineering and theoretical studies related to LaAlO3. The temperature dependence of domain ratio was preserved in the heating and cooling cycle except for the first heating process to 840 K. Therefore, the domain structure after heating to 840 K is intrinsic to the crystal. Accurate structure parameters were determined through unit-cell parameter calibration and domain-resolved structure analysis. The method for calibration of unit-cell parameters from twin crystal data was derived and used to solve the inconsistent unit-cell parameters between single crystal and powder data in the present and previous studies.
摘要：
结合来自同一样品的粉末衍射数据，成功地进行了LaAlO3拟摩面体孪晶晶体的域分辨同步加速器单晶X射线衍射研究。从一个单晶确定从微米到纳米到原子尺度的多尺度结构信息。在低于400K的温度下，畴比几乎没有变化，表明畴壁没有运动。在450至700K的温度范围内观察到指示畴壁运动的畴比变化，这与之前的机械测量结果一致。还发现四个孪生组分的比例变得相等（25％），低于相变温度。这些发现对于与LaAlO3相关的领域工程和理论研究具有重要意义。除第一加热过程至840K外，在加热和冷却循环中保留了畴比的温度依赖性。因此，加热到840K后的畴结构是晶体固有的。通过晶胞参数校准和域分辨结构分析确定了精确的结构参数。推导了从双晶数据中校准晶胞参数的方法，并将其用于解决当前和以前研究中单晶和粉末数据之间的晶胞参数不一致的问题。
