Folded network and structural transition in molten tin

Liang Xu,Qiang Wu,Howard Sheng,Yang Ren,Jian Chen,Songyi Chen,Xiaobing Zuo,Zhigang Wang,Wenge Yang,Jianrong Zeng

doi:10.1038/s41467-021-27742-2

Abstract

The fundamental relationships between the structure and properties of liquids are far from being well understood. For instance, the structural origins of many liquid anomalies still remain unclear, but liquid-liquid transitions (LLT) are believed to hold a key. However, experimental demonstrations of LLTs have been rather challenging. Here, we report experimental and theoretical evidence of a second-order-like LLT in molten tin, one which favors a percolating covalent bond network at high temperatures. The observed structural transition originates from the fluctuating metallic/covalent behavior of atomic bonding, and consequently a new paradigm of liquid structure emerges. The liquid structure, described in the form of a folded network, bridges two well-established structural models for disordered systems, i.e., the random packing of hard-spheres and a continuous random network, offering a large structural midground for liquids and glasses. Our findings provide an unparalleled physical picture of the atomic arrangement for a plethora of liquids, shedding light on the thermodynamic and dynamic anomalies of liquids but also entailing far-reaching implications for studying liquid polyamorphism and dynamical transitions in liquids.

Highlights

The fundamental relationships between the structure and properties of liquids are far from being well understood
We carried out state-of-the-art synchrotron X-ray scattering experiments and advanced ab initio thermodynamic analysis to quantify the transition in the liquid Sn, in hope to address the outstanding issue of how exactly the properties of anomalous liquids are affected by the structures
Our work establishes a new paradigm for liquid properties and the structures of disordered systems with complexity, but it will usher in new research on liquid polyamorphism[30,38], pivoting on the concept of bond-folding

Summary

Introduction

The fundamental relationships between the structure and properties of liquids are far from being well understood. Judging from the continuous changes in S(q) and g(r), we rule out the possibility of first-order phase transition of l-Sn, as confirmed by our constant pressure AIMD simulation (see Supplementary Fig. 5).

Results

Conclusion