Strontium Cobalt Oxide Misfit Nanotubes

Low-dimensional misfit layered compounds have been found to have ultralow thermal conductivity, which is attributed to their unique structure and the low dimensionality. There are a few studies reporting the preparation of sulfide-based misfit nanotubes but only one study on oxide-based analogs. In this investigation, we report a new oxide-based misfit nanotube derived from misfit layered strontium cobaltite. Thorough structural investigation by electron microscopy techniques, including electron diffraction, aberration corrected high-resolution (scanning) transmission electron microscopy, and electron energy-loss spectroscopy along with density functional theory calculations show that these nanotubes consist of alternating layers of SrCoO₂ and CoO₂. We have studied systematically the effect of base concentration on the structure and composition of the nanotubes, which reveals the importance of misfit stress to tightly roll the structure into tubular form and thus control the synthesis. Electronic structure calculations find that the structures are semiconducting with a ferrimagnetic ground state. Our studies further extend the family of bulk misfit layered oxides into the 1D realm with potential applications in thermoelectric and electronic devices.