Observation of the Pinning-Induced Crystal-Hexatic-Glass Transition in Two-Dimensional Colloidal Suspensions

Identification of the glass formation process in various conditions is of importance for fundamental understanding of the mechanism of glass transitions as well as for developments and applications of glassy materials. We investigate the role of pinning in driving the transformation of crystal into glass in two-dimensional colloidal suspensions of monodisperse microspheres. The pinning is produced by immobilizing a fraction of microspheres on the substrate of sample cells where the mobile microspheres sediment. Structurally, the crystal-hexatic-glass transition occurs with increasing the number fraction of pinning rho (pinning), and the orientational correlation exhibits a change from quasi-long-range to short-range order at rho (pinning) = 0.02. Interestingly, the dynamics shows a non-monotonic change with increasing the fraction of pinning. This is due to the competition between the disorder that enhances the dynamics and the pinning that hinders the particle motions. Our work highlights the important role of the pinning on the colloidal glass transition, which not only provides a new strategy to prevent crystallization forming glass, but also is helpful for understanding of the vitrification in colloidal systems.

Automated summary

Identification of the glass formation process under various conditions is crucial for understanding glass transitions and developing glass materials. By studying colloidal suspensions of monodisperse microspheres, researchers found that pinning a fraction of microspheres can drive the transition from crystal to glass. The dynamics show a non-monotonic change with increasing pinning fraction, highlighting the competition between disorder enhancing the dynamics and pinning hindering the particle motions.