Understanding and Predicting the Properties of Complex Materials: An Invited Talk

Predicting the properties of new materials prior to manufacturing is a topic attracting great industrial and scientific interest. Mechanical properties are currently of particular interest given the increasing demand for stronger, thinner, and more flexible materials in recent years. Property prediction for ceramic materials is facilitated by the periodic short- and long-range order of crystals. Based on J.C. Phillips’s theory for the ionicity of chemical bonding from ~1970, a method for predicting the hardness of covalent crystals was developed in the 2000s, which is now widely applied for the design of new superhard ceramic materials. It took another 10 years before the same predictions became possible for glassy systems, in which the lack of long-range order and the long time scales for relaxation greatly complicate the traditional modeling efforts. The key for making progress was to extract the key physics governing the macroscopic properties by using topological constraint theory, which was originally developed by the same J.C. Phillips around 1980. By further including the Gupta-Mauro temperature dependence of the constraints, the composition dependence of properties such as hardness and viscosity can be quantitatively predicted for oxide network glasses of industrial interest, such as borates and borosilicates.