کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5466826 | 1518304 | 2017 | 8 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Three-dimensional analysis of Eu dopant atoms in Ca-α-SiAlON via through-focus HAADF-STEM imaging
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
مهندسی مواد
فناوری نانو (نانو تکنولوژی)
پیش نمایش صفحه اول مقاله
![عکس صفحه اول مقاله: Three-dimensional analysis of Eu dopant atoms in Ca-α-SiAlON via through-focus HAADF-STEM imaging Three-dimensional analysis of Eu dopant atoms in Ca-α-SiAlON via through-focus HAADF-STEM imaging](/preview/png/5466826.png)
چکیده انگلیسی
Three-dimensional (3D) distributional analysis of individual dopant atoms in materials is important to development of optical, electronic, and magnetic materials. In this study, we adopted through-focus high-angle annular dark-field (HAADF) imaging for 3D distributional analysis of Eu dopant atoms in Ca-α-SiAlON phosphors. In this context, the effects of convergence semi-angle and Eu z-position on the HAADF image contrast were investigated. Multi-slice image simulation revealed that the contrast of the dopant site was sensitive to change of the defocus level. When the defocus level matched the depth position of a Eu atom, the contrast intensity was significantly increased. The large convergence semi-angle greatly increased the depth resolution because the electron beam tends spread instead of channeling along the atomic columns. Through-focus HAADF-STEM imaging was used to analyze the Eu atom distribution surrounding 10 nm cubes with defocus steps of 0.68 nm each. The contrast depth profile recorded with a narrow step width clearly analyzed the possible depth positions of Eu atoms. The radial distribution function obtained for the Eu dopants was analyzed using an atomic distribution model that was based on the assumption of random distribution. The result suggested that the Ca concentration did not affect the Eu distribution. The decreased fraction of neighboring Eu atoms along z-direction might be caused by the enhanced short-range Coulomb-like repulsive forces along the z-direction.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Ultramicroscopy - Volume 175, April 2017, Pages 97-104
Journal: Ultramicroscopy - Volume 175, April 2017, Pages 97-104
نویسندگان
Genki Saito, Fuuta Yamaki, Yuji Kunisada, Norihito Sakaguchi, Tomohiro Akiyama,