Researchers from Huazhong University of Science and Technology and the Science and Technology on Surface Physics and Chemistry Laboratory have uncovered a unique state of matter within glassy solids. This groundbreaking work, led by Professor Hai-Bin Yu and Dr. Qi Wang, demonstrates the existence of liquid-like clusters in these materials, a discovery published in the journal Next Materials.

The study delves into the long-held assumption in materials science that glassy solids, particularly metallic glasses, contain internal regions where atoms exhibit liquid-like behavior. Previous evidence for these regions was largely indirect, leaving their existence and characteristics somewhat speculative. This new research provides direct computational evidence of these clusters, termed liquid-like dissipation clusters (LDCs), which display damping properties similar to those of liquids but without the diffusive motion typically associated with a liquid state.

Professor Yu stated, “Our findings reveal the actual existence of localized liquid-like dissipation clusters in the glassy state, demonstrating a damping factor similar to liquids and a vanishing shear modulus.” The research highlights that these LDCs only appear at low temperatures and do not involve the diffusive movements seen in typical liquids.

The team used molecular dynamics simulations to analyze the dissipation characteristics at the atomic level. The results showed that these liquid-like clusters are responsible for the β’ relaxation process observed in metallic glasses. β’ relaxation, a dynamic process occurring at low temperatures, has been associated with liquid-like movements in previous studies but lacked a clear mechanistic understanding. This study bridges that gap by providing a computational basis for the phenomenon.

Interestingly, the research indicated that these clusters are not diffusive, distinguishing them from other known relaxation processes in glassy materials. This non-diffusive behavior is a key characteristic that sets the LDCs apart and suggests a new perspective on the internal dynamics of glassy solids.

Dr. Wang explained, “The low-temperature relaxation depicted in our study is not caused by atomic jumps and does not exhibit diffusive behavior. This unique state of condensed matter is dissipative but non-diffusive.” This distinction could have significant implications for understanding and manipulating the mechanical properties of metallic glasses, particularly at low temperatures.

Furthermore, the study suggests that the presence of these clusters can influence the mechanical behavior of metallic glasses, such as their plasticity. The research provides insights into why certain mechanical properties, like brittleness at intermediate temperatures, occur in these materials.

The discovery of LDCs not only validates a longstanding hypothesis in the field but also opens up new avenues for research. The team plans to further investigate the structural characteristics linked to these clusters and explore their potential implications for other phenomena in glassy materials, such as aging, crystallization, and deformation.

This research marks a significant step forward in the fundamental understanding of glassy solids. It provides a solid basis for the concept of liquid-like regions in these materials, challenging existing theories and potentially leading to new applications in materials science.

Journal Reference

Yu, Hai-Bin, and Qi Wang. “Liquid-like clusters in glassy solids as a unique state of matter: Dissipative but non-diffusive.” Next Materials 3 (2024): 100168. DOI: