Mechanical properties of CuCrO2 delafossite oxide single crystals

Abstract

The mechanical properties of delafossite oxide single crystals were studied. The polycrystalline material, prepared by self-combustion urea nitrate process, consisted of distinguishable platelet-like single crystals with an area of around 100 μm2 and 2 μm thick. All X-ray diffraction peaks were indexed as arising from CuCrO2 delafossite oxide, with a rhombohedral structure and space group R-3m. The inspection of loading curves and imprints produced by nanoindentation on individual single crystals disclosed a ductile-like behavior, with no cracks at the 7 mN load employed. The deformation mechanisms were discussed and contrasted with the index of plasticity for this material. In the ab-plane, hardness was (6.6 ± 1.6) GPa and elastic modulus was (101 ± 20) GPa, while the values obtained for the a(b)c-plane were ~ 55 GPa and ~ 87 GPa, respectively. The great variation of hardness and elastic modulus when observing the several single crystals tested can be related to the lamellar nature of this material, as well as the fact that the bonding between the stacking planes was not really strong.