Rajak Piu, Koch Christoph T, Bhattacharyya Somnath
Department of Metallurgical and Materials Engineering, Indian Institute of Technology Madras, Chennai, 600036, India.
Department of Physics, Humboldt-Universität zu Berlin, 12489 Berlin, Germany.
Ultramicroscopy. 2019 Apr;199:70-80. doi: 10.1016/j.ultramic.2019.02.012. Epub 2019 Feb 19.
Strain variation within nanoparticles plays a crucial role in defining important properties related to their applications. Transmission electron microscopy (TEM) based imaging techniques are mostly used to determine strain variation within nanoparticle and supporting amorphous carbon film induced artefact in measured strain variation. In this present work, an algorithm is reported which is capable of removing supporting film induced artefacts from measured strain variations within nanoparticles. The effectivity of the algorithm was tested using simulated TEM results which proves that the algorithm works satisfactorily down to t/t ratio of 0.25, where t and t defines the thicknesses along the electron beam of nanoparticle and supporting amorphous film respectively. These simulations also reveal that changing the atomic number of atoms within the nanoparticle, or the density of the amorphous carbon does not affect the algorithm's effectiveness. When the algorithm was applied on experimental TEM results of a TiO nanoparticle, it even worked well for t/t below 0.25, i.e. a relatively thick layer of amorphous carbon.
纳米颗粒内部的应变变化在定义与其应用相关的重要特性方面起着关键作用。基于透射电子显微镜（TEM）的成像技术主要用于确定纳米颗粒内部的应变变化以及测量应变变化时支撑非晶碳膜引起的伪像。在本工作中，报道了一种算法，该算法能够从纳米颗粒内测量的应变变化中去除支撑膜引起的伪像。使用模拟的TEM结果测试了该算法的有效性，结果证明该算法在t/t比低至0.25时仍能令人满意地工作，其中t和t分别定义了沿纳米颗粒和支撑非晶膜电子束方向的厚度。这些模拟还表明，改变纳米颗粒内原子的原子序数或非晶碳的密度不会影响该算法的有效性。当将该算法应用于TiO纳米颗粒的实验TEM结果时，即使在t/t低于0.25（即相对较厚的非晶碳层）的情况下，它也能很好地工作。
