Cockrell Cillian, Trachenko Kostya
School of Physical and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, UK.
Sci Adv. 2022 Aug 12;8(32):eabq5183. doi: 10.1126/sciadv.abq5183.
Universality aids consistent understanding of physical properties and states of matter where a theory predicts how a property of a phase (solid, liquid, and gas) changes with temperature or pressure. Here, we show that the matter above the critical point has a remarkable double universality. The first universality is the transition between the liquid-like and gas-like states seen in the crossover of the specific heat on the dynamical length with a fixed inversion point. The second universality is the operation of this effect in many supercritical fluids, including N, CO, Pb, HO, and Ar. Despite different structure and chemical bonding, the transition has the same fixed inversion point deep in the supercritical state. This advances our understanding of the supercritical state previously considered to be a featureless area on the phase diagram and a theoretical guide for improved deployment of supercritical fluids in green and environmental applications.
普遍性有助于对物质的物理性质和状态达成一致理解，其中一种理论预测相（固体、液体和气体）的一种性质如何随温度或压力变化。在此，我们表明临界点以上的物质具有显著的双重普遍性。第一种普遍性是在具有固定反转点的动力学长度上比热的交叉中所看到的类液态和气态之间的转变。第二种普遍性是这种效应在许多超临界流体中的作用，包括氮气、二氧化碳、铅、水和氩气。尽管结构和化学键不同，但该转变在超临界状态深处具有相同的固定反转点。这推进了我们对超临界状态的理解，此前超临界状态在相图上被认为是一个无特征的区域，并且为超临界流体在绿色和环境应用中的更好部署提供了理论指导。
