Thermoelectric materials have received considerable attention for the ability of converting heat into electricity via the solid state. Minimizing the lattice thermal conductivity has been proven to be effective to improve the efficiency of this conversion process. Recently, the concept of mosaicity in a single-phase has been realized to be a good option to increase thermoelectricity and develops the applications. We have achieved the desired mosaic structure in Cu2(S, Te). Although the microstructure of the mosaic crystals has been suggested by high-resolution transmission electron microscopy, the research on the lattice is limited, such as the atomic positions, mean-square-displacements, ect.. As the phonon scattering is related to the lattice, this measurement will provide the most direct probe into the origin of the anomalously low thermal conductivity in this material and will provide fundamental insights that can be used to design new, efficient thermoelectric materials.