Reducing the thermal conductivity of pyrochlores by cation substitution: Insights from molecular dynamics simulations

This paper presents the effect of cation substitution on the reduced thermal conductivity of A 2 B 2 O 7 pyrochlores. Molecular dynamics simulations were used to compare the thermal conductivity of 98 La 2 Zr 2 O 7 compounds with Zr 4+ cations substituted by seven different elements at varying concentrations, representing perhaps the largest set of data collected. In the case of single‐element substitution, the thermal conductivity is validated to approach its minimum near 50% dopant concentration, a stage corresponding to the maximum degree of structure disorder. The dependence of the minimum thermal conductivity on the B‐site dopant element is associated with the differences in size and mass between the cations. When the cations are substituted by multiple elements, the thermal conductivity of these pyrochlores does not exhibit a clear dependence on either mass or size disorder. Instead, a clustered pattern in the distribution of thermal conductivity can be identified, indicating that doping fewer elements with a proper concentration can reduce thermal conductivity as effectively as doping more elements.