Molecular dynamics simulation of thermodynamic properties and local structure of Na2CO3-K2CO3 eutectic salt during phase transition

Abstract

In this paper, the thermodynamic properties and local structure of Na2CO3-K2CO3 eutectic salt were simulated by using Born Mayer potential function. The phase transition temperature, solid specific heat capacity (Cp), liquid Cp and density of Na2CO3-K2CO3 eutectic salt were obtained by molecular dynamics calculation. Compared with the experimental results, the error of phase transition temperature, solid Cp(550K-650 K) were 6.32% and 1.61% respectively, which verified the accuracy and reliability of MD simulation method. Moreover, the local microstructure of Na2CO3-K2CO3 eutectic salt was characterized by radial distribution functions (RDF) and angular distribution functions (ADF), combined with the simulated results of the thermodynamic properties, revealed the variation of Cp, density, coefficient of thermal expansion and viscosity with the increasing temperature. Furthermore, the change of ions during the solid-liquid phase transition of Na2CO3-K2CO3 eutectic salt was analyzed from the microscopic point of view, and the microstructure of Na2CO3-K2CO3 eutectic salt in the solid-liquid phase was obtained.