Zhao Wenyang, Sakurai Kenji
University of Tsukuba, 1-1-1, Tennodai, Tsukuba, Ibaraki 305-0006, Japan.
National Institute for Materials Science, 1-2-1, Sengen, Tsukuba, Ibaraki 305-0047, Japan.
ACS Omega. 2017 Aug 8;2(8):4363-4369. doi: 10.1021/acsomega.7b00930. eCollection 2017 Aug 31.
The chemical garden, which has been known as the plant-growth-like diffusion of chemicals since the 17th century, has regained much attention in recent years. Significant progress in research not only promoted the understanding of the phenomenon itself but also suggested a prospective method of synthesizing new materials via the chemical garden route. It is extremely important to introduce new characterization techniques to provide more insights into chemical diffusion and element redistribution during the reaction process. The present article describes some successful applications of the realtime X-ray fluorescence (XRF) movie technique to observe each diffusing element. The protagonist of the movie is a chemical garden reaction growing from a seed of calcium salt and ferrous salt mixtures. Through observation by an XRF movie, it has been found that the growth rate and diffusion behavior of calcium and iron are very different. This results in a macroscopic diversity of the element composition in the finally precipitated chemical garden structures. The present research not only reconfirms the potential of fabricating gradient composites through the self-organized chemical garden approach but also demonstrates the attractive achievements of XRF movies. It has been demonstrated that the XRF movie is an indispensable realtime characterization technique for the study of chemical garden reactions or even other related diffusions.
化学花园自17世纪以来就被认为是化学品呈现出类似植物生长的扩散现象，近年来它再次受到了广泛关注。该研究取得的重大进展不仅增进了人们对这一现象本身的理解，还提出了一种通过化学花园途径合成新材料的前瞻性方法。引入新的表征技术对于深入了解反应过程中的化学扩散和元素再分布极为重要。本文介绍了实时X射线荧光（XRF）成像技术在观察各扩散元素方面的一些成功应用。该成像技术的主角是一种由钙盐和亚铁盐混合物种子生长而来的化学花园反应。通过XRF成像观察发现，钙和铁的生长速率及扩散行为差异很大。这导致最终沉淀的化学花园结构中元素组成呈现出宏观上的多样性。本研究不仅再次证实了通过自组织化学花园方法制备梯度复合材料的潜力，还展示了XRF成像的诱人成果。已经证明，XRF成像是研究化学花园反应乃至其他相关扩散过程不可或缺的实时表征技术。
