Giant thermal resistivity of interlaced nanoparticles

We present a theoretical study of thermal resistivity of ``interlaced crystals,'' recently discovered in hexagonal-CuInS$_{2}$ nanoparticles [1]. Interlaced crystals exhibit a perfect global Bravais lattice with two cations and multiple ordering patterns within the cation sublattice. The interlaced crystal consists of interlaced domains and phases where the corresponding phase/domain boundaries are not uniquely defined. Since there are no structural defects or strain, the interlacing has a minimal effect on electronic properties, but causes a large increase in phonon scattering at the boundaries. The size of domains reaches down to one nanometer, resulting in a high density of the boundaries, making interlaced crystals an attractive candidate for thermoelectric applications. Large-scale molecular dynamics calculations show orders of magnitude increase in the thermal resistivity caused by a high density of boundaries. This is a general effect, arising due to a mass disparity of the cations present in interlaced crystals. \\[4pt] [1] ``Interlaced crystals having a perfect Bravais lattices and complex chemical order revealed by real-space crystallography.'' X. Shen, et. al, Nature Comm. 10.1038/ncomms6431.