2026-05-20 東北大学
図1 X線発光分光で捉えた結晶化前の原子ネットワーク変化 ゼオライトが結晶になる前に、原子ネットワークの「ねじれ」が先に整い始めることを、X線発光分光によって捉えた。実験スペクトルと理論計算の比較から、結晶化初期にはシリケート骨格の三次元的な配列が変化していることがわかった。
＜関連情報＞
- https://www.tohoku.ac.jp/japanese/2026/05/press20260520-02-zeolite.html
- https://pubs.acs.org/doi/10.1021/jacs.6c03877
X線発光分光法により明らかになった、ゼオライト結晶化の前提条件としてのねじれ秩序化 Torsional Ordering as a Prerequisite for Zeolite Crystallization Revealed by X-ray Emission Spectroscopy
Kakeru Ninomiya,Ralph Ugalino,Koki Itamoto,Zhong Yin,Hisao Kiuchi,Yoshihisa Harada,Hideyuki Magara,Kenji Tsuda,Masami Terauchi,Toshiyuki Yokoi,and Maiko Nishibori
Journal of the American Chemical Society Published: May 19, 2026
DOI:https://doi.org/10.1021/jacs.6c03877
Abstract
Understanding how ordered crystals emerge from disordered precursors is a grand challenge in materials science. Resolving this question is critical for tailoring the properties of network materials, particularly zeolitic silicates, which are indispensable in energy and environmental catalysis. This challenge has been particularly acute as the key three-dimensional (3D) ordering of the silicate network has remained experimentally inaccessible. However, detailed knowledge of crystallization would enable tailoring of key properties for improved applications. Here, we provide direct observation of this process using O 1s X-ray emission spectroscopy (XES) as a spectroscopic ruler for the 3D network geometry. Supported by ab initio simulations, our results reveal the systematic evolution of the O–Si–O–Si torsion angles during the crystallization of an MWW-type zeolite. We discovered that the progressive ordering of these angles into a staggered conformation is a decisive early-stage event that precedes the formation of the crystalline framework. This work establishes O 1s XES as a powerful tool for probing local network topology, enabling quantitative access to key geometric parameters of 3D silicate networks, including bond distances, bond angles, and torsion angles. This reveals a fundamental principle: topological ordering is a distinct, precursorial event that occurs prior to the emergence of long-range crystalline order. This “topology-first” insight fundamentally advances the rational design of zeolites and other complex network materials with atomic-level precision.
