Laboratoire d'Etude des Textures et Application aux Matériaux (LETAM), UMR CNRS 7078, Ile du Saulcy, 57045 Metz Cedex 1, France.
Ultramicroscopy. 2010 Mar;110(4):269-77. doi: 10.1016/j.ultramic.2009.11.004. Epub 2009 Dec 16.
This study deals with the uncertainty of the measurement of lattice parameters by CBED using the kinematic approximation. The analysis of a large number of diffraction patterns acquired on a silicon sample at 93 K with a LaB(6) TEM without energy filter shows the presence of both the systematic and the random parts of errors. It is established that random errors follow the normal statistical distribution and that the precision quantified by the relative standard deviation is about 3-4 x 10(-4) for lattice parameter measurements made from single pattern. The error sources are analyzed, different ways of enhancement are reviewed, and a new approach is proposed. It is shown that both accuracy and precision can be simply improved by taking into account multiple patterns analysis for the determination of the actual voltage, the single lattice parameter "a" or the complete set of lattice parameters. The precision of about 1.5-2 x 10(-4) can be reached using a minimum of three HOLZ line patterns for the single "a" parameter and about 5 x 10(-4) for the complete set of lattice parameters using six diffraction patterns. The use of multiple patterns also allows overcoming the non-uniqueness of solution linked to the CBED studies.
本研究探讨了使用运动学近似法通过 CBED 测量晶格参数的不确定性。对在 93 K 下使用无能量过滤器的 LaB(6)TEM 在硅样品上获取的大量衍射图案进行分析表明，存在系统误差和随机误差。结果表明，随机误差符合正态统计分布，通过相对标准偏差量化的精度约为 3-4 x 10(-4)，这是对单个图案进行晶格参数测量的结果。对误差源进行了分析，回顾了不同的增强方法，并提出了一种新方法。结果表明，通过考虑多个图案分析来确定实际电压、单个晶格参数“a”或完整的晶格参数，可以简单地提高准确性和精度。使用最少三个 HOLZ 线图案可实现约 1.5-2 x 10(-4)的精度单个“a”参数，而使用六个衍射图案可实现完整晶格参数的约 5 x 10(-4)的精度。使用多个图案还可以克服与 CBED 研究相关的解的非唯一性。
