Xu Liang, Wang Zhigang, Chen Jian, Chen Songyi, Yang Wenge, Ren Yang, Zuo Xiaobing, Zeng Jianrong, Wu Qiang, Sheng Howard
National Key Laboratory of Shock Wave and Detonation Physics, Institute of Fluid Physics, China Academy of Engineering Physics, 621900, Mianyang, China.
Center for High Pressure Science and Technology Advanced Research, 201203, Shanghai, China.
Nat Commun. 2022 Jan 10;13(1):126. doi: 10.1038/s41467-021-27742-2.
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.
液体的结构与性质之间的基本关系远未得到充分理解。例如，许多液体异常现象的结构起源仍不明确，但液-液转变（LLT）被认为是关键所在。然而，LLT的实验证明颇具挑战性。在此，我们报告了熔融锡中类似二级相变的LLT的实验和理论证据，这种转变在高温下有利于形成渗流共价键网络。观察到的结构转变源于原子键的波动金属/共价行为，因此出现了一种新的液体结构范式。以折叠网络形式描述的液体结构，架起了两种已确立的无序系统结构模型之间的桥梁，即硬球的随机堆积和连续随机网络，为液体和玻璃提供了广阔的结构中间地带。我们的发现为大量液体的原子排列提供了无与伦比的物理图景，不仅揭示了液体的热力学和动力学异常现象，而且对研究液体的多态性和动力学转变具有深远意义。
