论文标题
负热膨胀和压力引起的锆钨的非形态化的起源，机器学习势
Origin of negative thermal expansion and pressure induced amorphization in zirconium tungstate from machine-learning potential
论文作者
论文摘要
了解材料在原子水平上的各种宏观压力体积 - 温度特性一直是物理学家和物质科学家的野心。特别是，某些材料（例如锆钨（ZRW2O8））具有多种外来特性，包括负热膨胀（NTE）和压力诱导的无形化（PIA）。在这里，使用基于机器的深度潜力，我们将ZRW2O8中的两种现象都追溯到一个共同的原子原子，在该起源中，非桥接O原子起着至关重要的作用。我们证明，非桥梁O原子赋予多面体振动的灵活性极大，并在加热或NTE上进行动力学驱动体积。此外，除了一定的临界压力之外，我们发现非桥接O原子的迁移会导致降低势能的额外键形成，这表明PIA是潜在驱动的一阶相变。最重要的是，我们确定了第二个临界压力，除了Zrw2O8的无定形阶段从可逆阶段转变为不可逆的阶段。
Understanding various macroscopic pressure-volume-temperature properties of materials on the atomistic level has always been an ambition for physicists and material scientists. Particularly, some materials such as zirconium tungstate (ZrW2O8), exhibit multiple exotic properties including negative thermal expansion (NTE) and pressure-induced amorphization (PIA). Here, using machine-learning based deep potential, we trace both of the phenomena in ZrW2O8 back to a common atomistic origin, where the nonbridging O atoms play a critical role. We demonstrate that the nonbridging O atoms confer great flexibility to vibration of polyhedrons, and kinetically drive volume shrinking on heating, or NTE. In addition, beyond a certain critical pressure, we find that the migration of nonbridging O atoms leads to additional bond formation that lowers the potential energy, suggesting that the PIA is a potential-driven first-order phase transition. Most importantly, we identify a second critical pressure beyond which the amorphous phase of ZrW2O8 undergoes a hidden phase transition from a reversible phase to an irreversible one.
