Department of Chemistry, Colorado State University, Fort Collins Colorado 80523, USA.
Laboratoire Charles Coulomb (L2C), University of Montpellier, CNRS, Montpellier, France.
Phys Rev Lett. 2019 Oct 25;123(17):175501. doi: 10.1103/PhysRevLett.123.175501.
Ultrastable vapor-deposited glasses display uncommon material properties. Most remarkably, upon heating they are believed to melt via a liquid front that originates at the free surface and propagates over a mesoscopic crossover length, before crossing over to bulk melting. We combine swap Monte Carlo with molecular dynamics simulations to prepare and melt isotropic amorphous films of unprecedendtly high kinetic stability. We are able to directly observe both bulk and front melting, and the crossover between them. We measure the front velocity over a broad range of conditions, and a crossover length scale that grows to nearly 400 particle diameters in the regime accessible to simulations. Our results disentangle the relative roles of kinetic stability and vapor deposition in the physical properties of stable glasses.
超稳定气相沉积玻璃表现出不同寻常的材料特性。最显著的是，人们认为它们在加热时会通过一个起始于自由表面并在介观交叉长度上传播的液体前沿进行熔化，然后再跨越到体相熔化。我们结合置换蒙特卡罗和分子动力学模拟，制备并熔化了具有前所未有的高动力学稳定性的各向同性非晶薄膜。我们能够直接观察到体相和前沿熔化，以及它们之间的交叉。我们在广泛的条件下测量了前沿速度，并在模拟可及的范围内测量了增长到近 400 个颗粒直径的交叉长度尺度。我们的结果阐明了动力学稳定性和气相沉积在稳定玻璃物理性质中的相对作用。
