Reviewed by Lexie CornerDec 6 2024
A research team led by Yuuki Kubo and Shiji Tsuneyuki from the University of Tokyo has developed an innovative computational method to efficiently determine the crystal structures of multiphase materials—powders composed of multiple crystal types. The findings were published in The Journal of Chemical Physics.
Schematic image of X-ray data-enhanced computational method. Image Credit: University of Tokyo
The method predicts structures directly from powder X-ray diffraction patterns, which are created when X-rays pass through crystals about the size of instant coffee particles. Unlike traditional approaches, this method does not require “lattice constants” and can analyze previously unprocessable experimental data. As a result, it offers a valuable tool for discovering new material phases and advancing material development.
Many materials can exist in multiple crystal structures, or "phases," within the same solid state. Understanding these structures is essential for analyzing material properties and developing new materials. Traditional methods, however, depend on the "lattice constant," a property unique to each crystal.
This approach requires prior knowledge of the crystal, making it challenging to analyze existing experimental data when the lattice constant is not accurately known. As a result, undiscovered crystal structures could remain hidden within already available data.
The crystal structures of the real world are extremely diverse. They are one of nature’s deepest mysteries. We thought that, in a way, we could get a glimpse of the depth of nature’s mysteries by developing our own method for determining unknown crystal structures.
Yuuki Kubo, University of Tokyo
Conventional methods use a variety of approaches but are often computationally intensive. To address this issue, the researchers developed a method capable of making predictions directly from experimental data. Their model is based on molecular dynamics, which simulates atomic motion by calculating interatomic forces. By integrating experimental X-ray diffraction data, they improved the alignment between the simulations and the experimental observations.
We did not believe this method was promising. We were surprised when we ran the test calculations, and the method performed far better than we had initially expected.
Yuuki Kubo, University of Tokyo
The researchers validated their method by applying it to well-studied materials, successfully reproducing the unique crystal structures of carbon (graphite and diamond) and silicon dioxide (low-quartz, low-cristobalite, and coesite). Despite its success, Kubo is already considering numerous potential next steps for further development.
We plan to apply this method to powder diffraction experimental data that have remained unutilized due to unsuccessful structural determination, aiming to discover new material phases. Furthermore, we aim to develop methods integrating experiments and simulations to determine not only crystal structures but also the structures of surfaces and interfaces.
Yuuki Kubo, University of Tokyo
Journal Reference:
Kubo, Y., et al. (2024) Data-assimilated crystal growth simulation for multiple crystalline phases. The Journal of Chemical Physics. doi.org/10.1063/5.0223390.