差分相位衬度技术解析催化剂表/界面电场潜在假象探讨  

Investigation of possible illusion in catalyst surface/interface electric fields resolved by differential phase contrast

作　　者：申嘉岳 李超 刘锐锐 SHEN Jiayue;LI Chao;LIU Ruirui(Center for Electron Microscopy,Tianjin Key Laboratory of Advanced Porous Functional Materials,Institute for New Energy Materials&Low-Carbon Technologies,School of Materials Science and Engineering,Tianjin University of Technology,Tianjin 300384,China)

机构地区：[1]天津理工大学材料科学与工程学院,新能源与低碳技术研究院先进功能多孔材料实验室电子显微镜中心,天津300384

出　　处：《高校化学工程学报》2024年第6期932-940,共9页Journal of Chemical Engineering of Chinese Universities

摘　　要：针对差分相位衬度技术(DPC)在解析催化剂表面电场时可能出现的电场不准确等问题,提出电镜像模拟的方法,对异质界面、不规则颗粒边缘,进行DPC像模拟,通过DPC与电场的关系解析电场信息。随后使用FEl-Titan Themis CubedG260-300真实拍摄参数模拟不同欠焦、像散下的颗粒边缘和异质界面的DPC结果。结果表明异质原子对电子束的散射差异导致界面处原子电场产生额外的偏移;对于具有不规则界面形状的样品,不规则表面形状会给电子束带来额外的偏转,上述结果均会导致表/界面电场解析结果不准确;随着样品厚度增加,电子束会产生相移,使得DPC所测的原子间电场不再准确;同时DPC拍摄中,欠焦量需要减小,从而避免欠焦带来的电场反转或偏移的假象;并且在拍摄过程中应关注三阶像差的数值并及时调整,使得DPC结果更为准确。In order to address electron inaccuracies in analyzing surface electric field of catalysts using differential phase contrast(DPC)technique,an electron microscopy image simulation method was proposed.DPC imaging simulations were performed on heterogeneous interfaces and irregular particle edges to analyze electric field information through DPC and electric field relationship.Subsequently,the DPC results of particle edges and heterogeneous interfaces under different defocus and astigmatism were simulated with real imaging parameters using a FEl-Titan Themis Cubed G260-300 microscope.The results reveal that the scattering differences of heterogeneous atoms by electron beam causes additional displacement of atomic electric field at the interface.For samples with irregular interfaces,the irregular surface shape results in additional beam deflections and leads to inaccurate determination of electric fields at the interface.As sample thickness increases,the electron beam generates phase shift,and leads to inaccuracies in atomic inter-electrostatic field measured by DPC.Moreover,reducing defocus amount during DPC imaging is necessary to avoid false electric field inversion or displacement caused by defocus.The value of third-fold astigmatism during imaging processes needs to be focused and adjustments should be made in a timely manner to obtain more accurate DPC results.

关 键 词：差分相位衬度技术 Au颗粒 Au-Pt异质界面 厚度 欠焦 像散 

分 类 号：O643.3[理学—物理化学]