Structure Modeling and Property Calculations of Amorphous Materials

Abstract

The demand in discovery of novel materials for a seemingly infinite list of applications is growing year by year. Even though it’s not uncommon to find the application for the material after its discovery upon experimentally studying its properties, it can be essential to be able to build the material to satisfy the specific need. This kind of targeted development for a specific application requires deep understanding of the “synthesis => structure => properties” sequence, and this is why insights into the mechanisms of the synthesis, structure formation and structure vs. properties relations are highly desired. Structural insights can be obtained through wide variety of spectroscopic techniques that are at our disposal nowadays. However, in solids, especially in disordered solids, these measured spectra provide a lot of room for misinterpretation, which leads to the necessity of supporting experimental findings with computations. My research is divided into 2 parts. Part I is dedicated to the computational attempts to enhance the experimental NMR findings by providing structure vs. NMR signal relations obtained via modeling and calculations. We provide means to reinterpret the NMR spectra of hafnia-silica sol-gel glasses (Chapter I), we explore silicon nitrides (Chapter II) and help in solving crystal structure of silicophosphate (Chapter III). Part II represents a successful attempt to develop a Reactive Force Field parameterization suitable to perform accurate simulations of the formation of silicon oxycarbide ceramic materials from polymer precursors. The results of my ReaxFF simulations are in good agreement with the experimental findings on PHMS-DVB system (Chapter I) and a different polymeric system, siloxane cross-linked with 4,4’-biphenol (Chapter II).