像差校正高分辨原子像的皮米精度定量计算及应用

Application and quantitative calculation of aberration-corrected high resolution images at picometer precision

为得到功能材料亚埃尺度的结构信息并进行定量分析,首先获得材料微观结构的像差校正高分辨原子像,之后对高分辨原子像进行形态学处理,拟合、定量计算每个原子的中心位置,得到原子极化皮米级位移,并进行误差分析。利用原子位置精确定位方法进一步对铁电薄膜PbTiO_(3)中的90°畴结构以及畴壁进行定量分析,得到了单畴的原子位移量以及“头对尾”畴界的单胞尺度极化。对LaCoO_(3)薄膜的原子分辨环形明场像进行定量分析,得到了氧八面体倾转角度大小及其在界面位置的变化。本方法可在皮米精度有效获得材料结构信息,并进行量化表征。

In order to obtain the atomic arrangement at picometer scale without artifacts,a series of morphological processing of the high resolution atomic scale images are carried out with numerical program.The center of each atoms is fitted and quantitatively calculated in order to obtain the displacements of polarization and error analysis at picometer level.By using this program,the 90-degree domain structure in ferroelectric thin film PbTiO_(3)is quantitatively analyzed,and the polarization of single domain and the"head to tail"domain wall at unit cell scale are calculated and illustrated as well.In addition,this approach is further applied to quantitatively analyze the annular bright-field image,and the oxygen octahedral tilting angles in the LaCoO_(3)thin film can be measured.The present method can obtain microstructure features of materials at picometer scale and calculate them quantitatively.