Kavli Institute for Theoretical Physics, University of California, Santa Barbara, CA, 93106, USA.
Nat Commun. 2018 Apr 10;9(1):1359. doi: 10.1038/s41467-018-03859-9.
The dynamical properties and mechanical functions of amorphous materials are governed by their microscopic structures, particularly the elasticity of the interaction networks, which is generally complicated by structural heterogeneity. This ubiquitous heterogeneous nature of amorphous materials is intriguingly attributed to a complex role of entropy. Here, we show in disordered networks that the vibrational entropy increases by creating phase-separated structures when the interaction connectivity is close to the onset of network rigidity. The stress energy, which conversely penalizes the heterogeneity, finally dominates a smaller vicinity of the rigidity threshold at the glass transition and creates a homogeneous intermediate phase. This picture of structures changing between homogeneous and heterogeneous phases by varying connectivity provides an interpretation of the transitions observed in chalcogenide glasses.
无定形材料的动力学性质和力学功能由其微观结构决定，特别是相互作用网络的弹性，而这种弹性通常因结构异质性而变得复杂。无定形材料普遍存在的这种异质性，其原因令人好奇地与熵的复杂作用有关。在这里，我们在无序网络中表明，当相互作用连接接近网络刚性的起始时，通过创建相分离结构，振动熵会增加。相反，由于异质性而受到惩罚的应力能最终在玻璃化转变时在刚性阈值的较小邻域中占主导地位，并产生均匀的中间相。通过改变连接性，在均匀相和非均匀相之间改变结构的这种图像为观察到的硫属玻璃转变提供了一种解释。
