Flux-Assisted Fabrication of Vertically Aligned Layered Double Hydroxide Plates on in Situ Formed Alumina Particles

详细信息    查看全文

• 作者：Fumitaka Hayashi ; Akemi Shirasaki ; Hajime Wagata ; Hideya Kamikawa ; Yoshie Aoki ; Shuji Oishi ; Katsuya Teshima
• 刊名：Crystal Growth & Design
• 出版年：2015
• 出版时间：February 4, 2015
• 年：2015
• 卷：15
• 期：2
• 页码：732-736
• 全文大小：406K
• ISSN：1528-7505

文摘

Layered double hydroxide (LDH) is an environmentally benign anion exchanger that can adsorb various toxic anions. In this work, we demonstrate the fabrication of plate-like Mg鈥揂l-type LDH crystals on in situ formed alumina particles using a flux method at a relatively low temperature (鈭?50 掳C). At or below 300 掳C, the melted Al source crystallized to form AlOOH or 纬-alumina particles in KNO₃鈥揘aNO₃ flux. However, LDH crystals did not form due to the inferior crystallization properties of the Mg precursor. Increasing the holding temperature up to 350 掳C and above facilitated crystallization of the dissolved Mg and Al species in flux to yield plate-like LDH crystals on the preformed alumina particles. Top-surface and cross-sectional FE-SEM and EPMA analyses revealed the vertical alignment of the crystalline LDH plates on the surface of the alumina particles. On the other hand, solid-state reactions did not yield these well-grown, plate-like LDH crystals. The TG-DTA profile of the LDH precursors with flux depicted the decomposition and crystallization events that the Al and Mg precursors undergo. On the basis of the results from these characterization studies, we propose a mechanism in which LDH crystals sequentially form on the surface of the alumina particles.