Phys.org December 2, 2024
The slow β, or Johari–Goldstein (JG) relaxation process, has been widely observed in glasses and is known to induce the stress relaxation associated with mechanical properties. So far, jumping motions of only a fraction of the particles were believed to contribute to the JG process in glass. However, there is no direct experimental evidence of the atomic-scale images due to the difficulties in microscopic observation. Researchers in Japan observed atomic motions in the quasi-spherical model ionic-glass-former calcium potassium nitrate. The experiment directly indicated that most particles underwent angstrom-scale motions in the time scale of the JG relaxation. Study of experiments and simulations revealed that most particles contributed to the JG process through unexpected collective nonjumping motions with angstrom-scale displacement, activated by jumping motions of a fraction of particles. According to the researchers their work has advanced our understanding of the puzzling mechanism of the JG process… read more. Open Access TECHNICAL ARTICLE
Graphical abstract. Credit: Acta Materialia, 4 November 2024, 120536