LAUSR

Abstract In this paper, both the facet-dependent electrical properties and mechanical stability of submicron-sized polyhedral Cu2O are investigated with in-situ resistivity measurements with pressure up to 25.0 GPa. The pressure-induced morphology changes are characterized by scanning/transmission electron microscopy. X-ray photoelectron spectroscopy measurements are also adopted to rationalize the diversity of the electrical resistivity of polyhedral Cu2O under compression. The electrical properties of cubic, truncated octahedral, and octahedral Cu2O show extremely different pressure dependence, which can be attributed to the preferential adsorption of oxygen on Cu2O (111) facet. The anomalous changes in electrical resistivity at 0.7–2.2, 8.5, 10.3, and 21.6 GPa are due to pressure-induced structural phase transitions of the Cu2O crystals. The dramatic reductions of resistivity in cubes and octahedras at 15.0 GPa and of truncated octahedras at 21.2 GPa are driven by pressure-induced crush and nanocrystallization of Cu2O crystals. The mechanical stability of truncated octahedral Cu2O is better than those of both cubic and octahedral Cu2O. Our results not only elucidate the underlying mechanisms for understanding the two previously reported pressure-dependent electrical resistance change trends difference, but also give a reasonably explanation of the facet-dependent mechanical property of Cu2O.