Grain-size dependent thermal conductivity of Gd2Zr2O7 ceramics

In this work, the grain-size dependent thermal conductivity of Gd 2 Zr 2 O 7 (GZO) ceramics has been studied. The investigation show that the thermal conductivity limit of the GZO ceramic can be achieved when the grain size is reduced to ∼7.5 nm. The very low thermal conductivity can be related to the high volume fraction of grain boundary/triple junction phases (GB/TJ) in nanocrystalline GZO ceramic, which is comparable to that of the grain phase. This result demonstrates that reducing grain size is a valid strategy to decrease the thermal conductivity in polycrystalline materials. Significantly, this grain-size dependent thermal conductivity can be described by a simple composite model, which treated the nanocrystalline GZO ceramic as a two-phase mixture model consisting of grain phase and GB/TJ phase.