Thermal transport property in pyrochlore-type and fluorite-type A(2)B(2)O(7) oxides by molecular dynamics simulation

JW Che and XZ Wang and XY Liu and GY Liang and SL Zhang, INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER, 182, 122038 (2022).

DOI: 10.1016/j.ijheatmasstransfer.2021.122038

Pyrochlore-type (P-type) and fluorite-type (F-type) rare-earth A(2)B(2)O(7) -type oxides attract extensive interest in engineering applications in which ultralow thermal conductivity is strongly required for improving energy-utilization efficiency and thermal management. Herein, thermal transport properties of P-type and F-type A(2)B(2)O(7) (A = Y, La, Nd, Sm, Gd, Yb; B = Zr, Ce, Hf) was systematically investigated using molecular dynamics. The thermal conductivity of F-type structures was found to be 0.83 similar to@3.37 W.m(-1)K(-1), which is 30%similar to 50% of that of P-type structures. Such an low thermal conductivity is due to the stronger phonon scattering in F-type structures resulting from the inhomogeneous interatomic bonding. It was also found that the thermal conductivities of F-type A(2)B(2)O(7) being less dependent on temperature and closer to the theoretical minimum values due to the presence of amorphous-like phonon modes. Finally, we identified the optimal compositions in F-type A(2)B(2)O(7) family for achieving lowest thermal conductivity at high temperatures. This study suggests that enhancing the inhomogeneity of interatomic bonding can enable low thermal conductivity in simple-composition materials. (C) 2021 Elsevier Ltd. All rights reserved.

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