Atomistic Structure and Thermodynamic Properties of Siloxane Pyrolyzed Amorphous Silicon Oxycarbide

Atomistic models of amorphous silicon oxycarbide, a-SiCO with different compositional range between SiO ₂ and SiC are constructed by rapid quenching. Structural models consisting of 528–568 atoms are fully optimized by molecular mechanics based on ReaxFF force fields. The addition of carbon into SiO ₂ glass stiffens the network and increases the bulk modulus. For better understanding the thermodynamics properties of a-SiCO, the effect of pressure and temperature on the bulk modulus, heat capacity, Debye temperature and coefficient of thermal expansion are derived by the quasi-harmonic Debye model in virtue of standard thermodynamic relations.