Temperature effect on mechanical and thermal properties of multicomponent rare-earth zirconate pyrochlores

In order to explore the temperature-dependent structural and mechanical/thermal property evolution of pyrochlores, multicomponent rare-earth zirconates (4RE(1/4))(2)Zr2O7 (RE = La, Nd, Sm, Eu, and Gd) and corresponding single-component compounds are investigated by molecular dynamics simulations. The structural parameters and mechanical/thermal properties reported in experiments are well reproduced. With temperature enhancement, the bond lengths become large and polyhedrons tend to deform more, whereas the second-order elastic constants and polycrystalline mechanical moduli gradually reduce. It can be explained by the obvious change of (ZrO6) polyhedrons originating from the Zr-O bond stretching. Furthermore, thermal conductivities show decreasing tendency owing to a sharp decline of the phonon mean free path related to enhanced phonon scattering. As a big influence of temperature on (ZrO6) polyhedrons occurs, the multicomponent design at the Zr-site is suggested to be paid more attention. This work is expected to shield light on the design for multicomponent pyrochlores as thermal barrier coatings.

Automated summary

This study investigates the temperature-dependent structural and mechanical/thermal property evolution of multicomponent rare-earth zirconates. Molecular dynamics simulations are used to reproduce the experimental results. It is found that with increasing temperature, the polyhedrons deform more, resulting in reduced mechanical properties and thermal conductivities. The multicomponent design at the Zr-site is suggested to be important in the design of thermal barrier coatings using pyrochlores.