First‐principles study of the thermal properties of Zr2C and Zr2CO

Abstract First‐principles calculations of lattice thermal conductivities and thermodynamic properties of Zr 2 C and Zr 2 CO were performed using the quasi‐harmonic approximation. Oxygen in the lattice gives Zr 2 CO higher bonding strength than Zr 2 C. Thus, the mechanical properties of Zr 2 C are enhanced when the vacancies in its crystal structure are filled with oxygen. Among the critical parameters that determine the lattice thermal conductivity, Zr 2 C has significantly higher Grüneisen parameters, thus Zr 2 C has lower lattice thermal conductivity than Zr 2 CO. In addition, Zr 2 CO has a higher heat capacity and thermal expansion coefficient than Zr 2 C at most temperatures. These results indicate that the addition of oxygen has increased the stiffness and thermal conductivity of zirconium carbide that contains a large fraction of carbon vacancies due to the filling of vacancies in the Zr 2 C lattice and the formation of Zr–O bonds.