Continuous observation of the shear melting process in colloidal crystals with 1-millisecond time resolution

A joint research group has successfully developed and established a synchrotron radiation rheo-SAXS/USAXS measurement system on a beamline at the large synchrotron radiation facility "SPring-8" to perform in-situ observations of microparticle structures under shear. Using this system, the team succeeded in directly observing the process in which a colloidal crystal begins to change its structure after just 1 millisecond of being subjected to an impactful shear force. The research group consisted of Tenure-Track Researcher Keishi Akada, Researcher Hiroyuki Iwamoto (at the time of research), and Senior Researcher Hiroshi Sekiguchi from the Japan Synchrotron Radiation Research Institute (JASRI); Researcher Tatsuya Yamada (at the time of the study) and Researcher Syogo Tejima from the Research Organization for Information Science and Technology (RIST); Graduate Student Ryoichi Ishibashi, Associate Professor Motoyoshi Kobayashi, and Specially Appointed Professor Jun-ichi Fujita from the University of Tsukuba; and Soichiro Okubo from Sumitomo Electric Industries (at the time of the study).

There is no other example in the world of synchrotron radiation rheo-SAXS being used to continuously observe the irreversible process of shear melting with a 1-millisecond time resolution. This achievement overturns the conventional view that changes in soft matter occur slowly. Furthermore, the study revealed that under impact shear, the crystal melts along with "clustering," a phenomenon where particles temporarily gather in the direction of the flow.

The measurement infrastructure established at SPring-8 is expected to be useful for clarifying instantaneous phase transitions in non-equilibrium soft matter and for designing the flow behavior of colloidal materials. The findings were published in Communications Chemistry. Shear melting of colloidal crystal and schematic of time-resolved rheo-SAXS system.

Provided by JASRI Journal Information Publication: Communications Chemistry Title: Impact-shear-induced millisecond clustering during shear melting of colloidal crystals DOI: 10.1038/s42004-026-02004-8 Chemistry This article has been translated by JST with permission from The Science News Ltd. (https://sci-news.

co.jp/). Unauthorized reproduction of the article and photographs is prohibited.

This article has been translated by JST with permission from The Science News Ltd. (https://sci-news.co.

jp/). Unauthorized reproduction of the article and photographs is prohibited.