分享
编辑者： Svitlana Velhush
A unified microscopic theory reveals that the observed strong dielectric anisotropy and enhanced in-plane conductivity in nanoconfined water arise from strong in-plane polarization correlations in the hydrogen-bond network. Learn more: go.aps.org/4AJFhWH
当水被夹在两块相距仅几纳米的板之间时，它便不再表现得像普通液体。其沿层平面方向的介电常数飙升至一千以上，而垂直于壁面方向则降至二至三个单位。与此同时，质子导电率急剧上升。
把水视为具有恒定介电常数的简单介质这一常规观念在此行不通。当间隙厚度小于五纳米时，几乎全部水都处于表面影响区内。分子无法在三维空间中自由取向——其偶极被迫平躺在平面内。
这种限制延长了相邻偶极之间的关联。取代局部涨落的是由数百个分子组成的畴，它们通过氢键相连并协同振荡。此类集体运动增强了平面对电场的响应，同时抑制了垂直方向的响应。
基于线性响应并采用极化关联指数核构建的理论模型，给出了普适的标度律。介电常数与关联长度的平方成正比增长，而导电率则与层厚成反比。计算结果与厚度在一至五纳米范围内的实验在定量上吻合。
纳米受限水表现得像一种具有铁电特征的关联极性液体。其性质并非由电容器的几何形状决定，而是由偶极的集体涨落决定。这为在纳米通道和纳米孔中调控离子输运与化学活性开辟了道路。
理解这一机制，使人们能够预测水在生物膜、石墨烯通道以及层厚以纳米计量的纳米材料中的行为。
The Giant Permittivity of Nanoconfined Water
Uranium ditelluride is revealing that electron pairs can persist in an organized wave pattern even after superconductivity disappears. Researchers at the University of Illinois found evidence of these pair density waves on the material’s surface, including above its
HKUST Researchers Redraw the Boundary between Phases of Matter A research team led by Prof. Haruki WATANABE, Professor in the Department of Physics and the Jockey Club Institute for Advanced Study (IAS) at HKUST, in collaboration with Prof. Yukitoshi MOTOME and graduate student
