Glass-like thermal conductivity of Nd_2/3-xLi _3xTiO₃ bulk ceramics with nanochessboard superlattice structure

We report the thermal conductivity of bulk Nd_2/3-xLi _3xTiO₃ (0.047<x<0.151) ceramics, prepared by a conventional solid-state reaction method. These materials possess a nanochessboard superlattice structure present in every crystallite, with a superperiodicity of ∼4 nm along the [110] orientation. A glass-like low thermal conductivity (1-2 W/(mK)) was shown in the Nd_2/3-xLi _3xTiO₃ system and it was almost temperature independent. Moreover, a shorter periodic length of the superlattice structure caused a lower thermal conductivity due to the increased interface phonon scattering. The low thermal conductivity is not always seen in oxide materials. In combination with the tunability of the electrical properties and the maintainability of the microstructure, we believe that this work provides an insight into the nanostructure design for the development of novel oxide thermoelectric materials.