Tokoro Hiroko, Fukui Junpei, Watanabe Koki, Yoshikiyo Marie, Namai Asuka, Ohkoshi Shin-Ichi
Department of Materials Science, Faculty of Pure and Applied Sciences, University of Tsukuba 1-1-1 Tennodai, Tsukuba Ibaraki 305-8573 Japan
Department of Chemistry, School of Science, The University of Tokyo 7-3-1 Hongo, Bunkyo-ku Tokyo 113-0033 Japan
RSC Adv. 2020 Oct 29;10(65):39611-39616. doi: 10.1039/d0ra07256g. eCollection 2020 Oct 27.
Herein we report crystal growth control of rod-shaped ε-FeO nanocrystals by developing a synthesis based on the sol-gel technique using β-FeO(OH) as a seed in the presence of a barium cation. ε-FeO nanocrystals are obtained over a wide calcination temperature range between 800 °C and 1000 °C. A low calcination temperature (800 °C) provides an almost cubic rectangular-shaped ε-FeO nanocrystal with an aspect ratio of 1.4, whereas a high calcination temperature (1000 °C) provides an elongated rod-shaped ε-FeO nanocrystal with an aspect ratio of 3.3. Such systematic anisotropic growth of ε-FeO is achieved due to the wide calcination temperature in the presence of barium cations. The surface energy and the anisotropic adsorption of barium on the surface of ε-FeO can explain the anisotropic crystal growth of rod-shaped ε-FeO along the crystallographic -axis. The present work may provide important knowledge about how to control the anisotropic crystal shape of nanomaterials.
在此，我们报道了通过开发一种基于溶胶 - 凝胶技术的合成方法来控制棒状ε - FeO纳米晶体的晶体生长，该方法以β - FeO(OH)为晶种，在钡阳离子存在的情况下进行。在800℃至1000℃的宽煅烧温度范围内获得了ε - FeO纳米晶体。较低的煅烧温度（800℃）提供了一种长宽比为1.4的近似立方矩形的ε - FeO纳米晶体，而较高的煅烧温度（1000℃）提供了一种长宽比为3.3的细长棒状ε - FeO纳米晶体。由于在钡阳离子存在下煅烧温度范围较宽，实现了ε - FeO如此系统的各向异性生长。钡在ε - FeO表面的表面能和各向异性吸附可以解释棒状ε - FeO沿晶轴的各向异性晶体生长。本工作可能为如何控制纳米材料的各向异性晶体形状提供重要知识。
