Obtaining ZnO/CuO Particles in a Direct Current Glow Discharge in an Air Stream

Ultrafine double oxides of zinc and copper were synthesized by a simple one-step method from nitrates under the action of low-temperature plasma of an atmospheric pressure glow discharge in air without organic substrates and surfactants. The treated nitrates were placed on the cathode of the discharge system. The properties of the plasma were investigated by emission spectroscopy in the visible region of the spectrum. The values of rotational and vibrational temperatures of nitrogen without nitrates and in the presence of nitrates were determined from the emission of the second positive nitrogen system. It is shown that the introduction of nitrates significantly decreases the rotational temperature of nitrogen molecules. The change in the spectral composition of radiation, when nitrates are introduced into the discharge, was investigated. The obtained samples were characterized using scanning electron microscopy, X-ray diffraction spectroscopy, and energy dispersive analysis, and the gas component of the plasma was studied using emission spectroscopy. As a result of the interaction of plasma with zinc and copper nitrates, the corresponding zinc and copper oxides with the composition ZnO; CuO; ZnO0.25CuO0.75; ZnO0.75CuO0.25; ZnO0.5CuO0.5 were formed. The composition was confirmed by XRD and EDS data. The surface morphology was studied using a scanning electron microscope; the surface of the powders is well developed, and the particles have ellipsoidal shapes. Based on the emission spectra, possible mechanisms for forming oxides have been proposed. Presumably, the main contribution to the formation of oxide particles is made by ion bombardment of the cathode, followed by the transfer of nitrates into the gas phase, where they decompose to oxides.