Prediction of the lattice thermal conductivity of zircon and the cubic and monoclinic phases of zirconia by molecular dynamics simulation

Zirconia (ZrO2) and zircon (ZrSiO4) have high strengths and stabilities at high temperatures and also have remarkable thermal properties, such as rather low thermal conductivities. In the present research, the phonon thermal conductivity of zircon and two polymorphs (cubic and monoclinic phases) of zirconia are investigated. For this purpose, equilibrium molecular dynamics simulations using classical interatomic potentials and the Green-Kubo formalism are presented. The results are given in detail over a wide temperature range, with a 100 K temperature step, from 200 K to 2400 K and 200 K to 1400 K for the cubic and monoclinic phases of zirconia, respectively, and 200 K to 1400 K for zircon. The temperature dependence of the lattice parameters and the equilibrium atomic volumes show good agreement with available experimental data. Next, the phonon thermal conductivity is calculated by analysing the raw data of the heat current autocorrelation function. The results illustrate that the above-mentioned materials have quite low thermal conductivities that are dependent on temperature. It is also shown that the lattice thermal conductivity of the different phases of zirconia and zircon can be decomposed into three contributions due to the acoustic short-range, long-range phonon and optical phonons modes. Finally, the thermal conductivity results from this study are compared with previous experimental studies and very good agreement is found.