Study of Phase Composition of CuO/Cu2O Nanoparticles Produced in the Plasma of a Low-Pressure Arc Discharge

Resumo

The influence of synthesis parameters on peculiar features of the forming crystalline phases of copper oxide nanoparticles is inspected via electron microscopy, IR spectroscopy, X-ray diffraction, and differential thermal analysis. The nanopowders are produced through the evaporation of a bulk copper cathode by a low-pressure arc discharge with successive condensation of plasma-chemical reaction products on the substrate. The partial pressure of oxygen in the feeding Ar/O₂ gas mixture is varied in a range of 3–30 Pa. The aforementioned methods reveal that particles are formed with controllable dispersion, phase composition, and structural features. The control of characteristics of nanodispersed oxides is based on their formation mechanisms that are brought by the competing impact of coagulation and diffusion processes. The synthesis products are spherical powders of copper oxides comprising a mixture of crystalline phases with the prevalence of CuO, whose average particle sizes are 10–20 nm. The qualitative differences in samples for the opposite partial pressures of oxygen (\({P_{{O_2}}} = 3\) and 30 Pa) are confirmed through the interpretation of IR and DTA spectra. The transmission bands over a wavenumber range of 440–530 cm^–1, being intrinsic of CuO, are distinguished from those of Cu₂O at 1130, 2923, and 2970 cm^–1. The discrepancy of the DTA curves is due to the diversity in thermal stability of CuO/Cu₂O oxides at their different proportion in samples.