Modulated crystallographic shear structure in titanium–chromium oxides: their structure and phonon-transport properties

Advancements in phonon engineering have propelled the study of heat conduction within nanostructures, focusing on the wave nature of phonons for thermal conductivity manipulation. This work investigates the annealing-induced structural transformation of titanium–chromium oxide crystals, highlighting a role in modulating thermal conductivity through the regularization of crystallographic shear (CS) plane spacing. Utilizing high-angle annular dark-field scanning transmission electron microscopy and selected-area electron diffraction, a transformation from disordered to ordered arrangements of CS planes was observed through annealing at high temperatures. The thermal conductivity increased following annealing. The variability observed in the spacing of CS planes before annealing implies that phonon Anderson localization might play a role in the changes in thermal conductivity.