Thermodynamic properties of borate glasses by molecular dynamics simulations

Abstract

The molecular dynamics method was used to examine the B2O3 and borate glasses. The discontinuity in each of the thermodynamic factors such as the transition temperature, specific heat, thermal expansion and thermal compressibility is detected and checked by the so-called Prigogine-Defay ratio and it is found that this ratio exceeds unity for the systems studied. This behaviour indicates that multiple order parameters are required to characterize the glassy state. Also it is found that the formation of diborate groups in borate glasses reduces the value of the Prigogine-Defay ratio Pi , while the formation of groups with non-bridging oxygen ions increases the value of Pi , i.e. increases the number of order parameters.