Johnston-Peck Aaron C, Maier Russell A
Material Measurement Laboratory National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, MD 20899 United States.
J Am Ceram Soc. 2023 Feb;106(2):1490-1499. doi: 10.1111/jace.18814. Epub 2022 Oct 5.
Adlayers on C-plane (0001) and R-plane terminated surfaces of corundum phase aluminum oxide were synthesized by annealing mixtures of two oxide powders, aluminum oxide with an additive. Using high-angle annular dark field scanning transmission electron microscopy, the adsorbed layers were characterized, and image simulations aided interpretation of the results. The adlayers were pseudomorphic, one atomic layer thick and with a fractional site occupancy. Atomic positions of the adlayer atoms relaxed and changed relative to the bulk structure, where there is evidence that the magnitude of the relaxation is sensitive to the ionic radius of the adsorbate. The pseudomorphic adlayer structure formed for different elements including, but not limited to, the lanthanides (i.e., Ge, Ba and Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm).
通过对两种氧化物粉末（氧化铝与一种添加剂）的混合物进行退火处理，在刚玉相氧化铝的C面（0001）和R面终止表面上合成了吸附层。使用高角度环形暗场扫描透射电子显微镜对吸附层进行了表征，并通过图像模拟辅助对结果进行了解释。吸附层是赝晶的，厚度为一个原子层，且具有部分占位。吸附层原子的原子位置相对于体相结构发生了弛豫和变化，有证据表明弛豫的幅度对吸附质的离子半径敏感。为不同元素形成了赝晶吸附层结构，这些元素包括但不限于镧系元素（即Ge、Ba以及Ln = La、Ce、Pr、Nd、Sm、Eu、Gd、Dy、Ho、Er、Tm）。
