Ni4Mo短範囲規則合金のHRTEM像シミュレーション

概要

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High resolution transmission electron microscope (HRTEM) images of short range order (SRO) in Ni$_4$Mo were investigated by means of multi-slice image simulation with various observation conditions. An energy-filtered field emission TEM (EF-FETEM) and a conventional TEM (CTEM) with accelerating voltage of 200 kV were assumed in the simulation. In case of the EF-FETEM, the dot-contrast related to the fundamental $fcc$ lattice and the SRO structure is imaged clearly over wide ranges specimen thickness $t$ and defocus distance $\Delta f$. The obtained images of SRO sensitively depend on the values of $t$ and $\Delta f$, which can be interpreted in terms of the whole or partial projected potential of atom columns. For the CTEM, on the other hand, the ranges of $t$ and $\Delta f$ in which the $fcc$ lattice is imaged are limited due to less contribution of higher order reflections to the image. It is difficult to analyze the SRO structures in atomic level from the HRTEM images when the image contrast of the $fcc$ matrix is weak.
九州大学の論文
2001-03-30