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The microstructural properties of polycrystalline CuO powders and their evolution during controlled high energetic ball milling (HEBM) were studied using conventional X-ray diffraction (XRD) techniques and in situ temperature-dependent small and wide angle scattering (SAXS-WAXS) synchrotron radiation experiments. Volume weighted average grain size, unit cell expansion, oxygen deficiency, and microstrain values as a function of milling time were obtained from XRD. SAXS data revealed different nanostructures for samples synthesized by one-step solid-state reaction (SSR) or HEBM-treated powders. The latter presented the characteristics of a multilayered nanoscale solid system with surface fractal behavior. Correlation of the XRD microstructural parameters and the power law exponent of the SAXS curves as a function of temperature and milling time provided a coherent picture of the structure of HEBM-treated powders. The overall structural information presented in this article may shed some light on the macroscopic physical properties of CuO nanostructures.

Enhanced magnetic behavior, exchange bias effect, and dielectric property of BiFeO3 incorporated in (BiFeO3)0.50 (Co0.4Zn0.4Cu0.2 Fe2O4)0.5 nanocomposite AIP Advances 4, 037112 (2014); 10.1063/1.4869077 Core/shell magnetism in NiO nanoparticles J. Appl. Phys. 114, 083906 (2013); 10.1063/1.4819807 Structural and room-temperature ferromagnetic properties of Fe-doped CuO nanocrystalsNanostructures of cupric oxide (CuO) obtained by ball milling show drastic changes in its magnetic behavior that cannot be only associated to a size effect. While sample of average size D ¼ 29 nm presents a magnetic behavior that resembles that of bulk material with a N eel temperature of 195 K, another sample with D ¼ 24 nm displays a departure from the magnetic features typical of bulk CuO and has magnetic hardness characteristics at low temperatures. Both samples show irreversibility above room temperature and shifts in their hysteresis loops along magnetization and field axis when field cooled in a H FC ¼ 50 kOe to 10 K. At this temperature, an apparent exchange bias like field, "H EB ", 0.17 and 1.06 kOe were estimated for 29 and 24 nm CuO samples, respectively. Magnetic behavior differences observed in samples subjected to distinct milling times are explained as due to a proposed model for milled CuO consisting of a multilayer configuration where interfaces comprise uneven structural disorder and oxygen deficiencies, which generate a peculiar antiferromagnetic/ferromagnetic interface configuration. V C 2012 American Institute of Physics. [http://dx.