Dielectric Barrier Discharge (DBD) is a promising technique for producing plasma in atmospheric pressure and is gaining emphasis in several areas, especially in the biomedical and textile industries, among other. This is due to the fact that this plasma does not reach high temperatures, enabling its use on thermally sensitive materials. However, there is still the need for the development of research relating to the field of physical mechanisms of non-thermal plasma. In this work, we studied the behavior of plasma in DBD equipment, varying distance between electrodes. For this study, two distinct characterization techniques were used. The first, the Lissajous Figures method, is effective and precise in the electrical characterization of DBD equipment. The second technique used, Optical Emission Spectroscopy (OES) is an effective tool in the diagnosis of plasma. This tool enables the identification of excited species in plasma. With the data produced, it was possible to identify an appropriate distance for producing plasma with a higher intensity and homogeneity of active species.

In this work, the plasma was used in the dielectric barrier discharge (DBD) technique for modifying the high-density polyethylene (HDPE) surface. The treatments were performed via argon or oxygen, for 10 min, at a frequency of 820 Hz, voltage of 20 kV, 2 mm distance between electrodes, and atmospheric pressure. The efficiency of the plasma was determined through the triple Langmuir probe to check if it had enough energy to promote chemical changes on the material surface. Physicochemical changes were diagnosed through surface characterization techniques such as contact angle, attenuated total reflection to Fourier transform infrared spectroscopy (ATR-FTIR), X-ray excited photoelectron spectroscopy (XPS), and atomic force microscopy (AFM). Plasma electronics temperature showed that it has enough energy to break or form chemical bonds on the material surface, impacting its wettability directly. The wettability test was performed before and after treatment through the sessile drop, using distilled water, glycerin, and dimethylformamide, to the profile of surface tensions by the Fowkes method, analyzing the contact angle variation. ATR-FTIR and XPS analyses showed that groups and bonds were altered or generated on the surface when compared with the untreated sample. The AFM showed a change in roughness, and this directly affected the increase of wettability.

The fabrics with copper or copper oxide deposition are of considerable interest because of exceptional antibacterial properties, which are useable in medical, textiles, and hygiene applications. Unfortunately, the conventional techniques take long processing time, complex equipment, and combination of several processing steps (nanoparticles synthesis and their deposition on fabrics). In this novel study, cathodic cage plasma deposition assisted with copper cathodic cage is used for the synthesis of the copper oxide on polyester and polyamide fabrics. For the enhancement of synthesis efficiency, the effect of cathodic cage lid thickness is also investigated. The samples are assessed by using scanning electron microscopy, elemental dispersive spectroscopy, and X‐ray photoelectron spectroscopy. It is found that using cathodic cage plasma deposition, fabrics can be successfully synthesized by the copper oxide with comparatively small treatment time, cost‐effectively, and environmentally friendly. Interestingly, cathodic cage plasma treatment is already proved to be working effectively on industrial scale; thus, it is predicted to be of noteworthy importance for fabrics processing on large‐scale garments manufacturing and hospitals.

Experimental and theoretical investigations of the structure and optical properties of Al-doped ZnO (AZO) thin films produced by magnetron sputtering under different values of electric current were conducted. The XRD results confirm the formation of the AZO thin films with hexagonal wurtzite structure, with preferential orientation along the crystallographic plane (002), direction c. The increment of electric current allowed an increase in average crystallite size. The FE-SEM and AFM images analyses of the AZO films revealed the occurrence of nucleation on the substrate surface that formed films with granular and rough structure. The higher substrate temperature caused by the higher value of electric current had influence on the grain size and thickness (ranging from 974 to 1500 nm) of the formed thin films. Due to the high absorption of free carriers, the optical transmittance of the AZO films was acceptable for the visible spectrum and limited to the near infrared region. The energy band gap values for both AZO films, measured from the optical transmission spectra, were ideal for semiconductor applications. The ab initio calculations using DFT and the method LSDA + U along with the correction of Hubbard were successfully applied to investigate the structural and optical effects. The band structures of the pure ZnO and ZnO:Al, calculated in this work, presented Eg values close to the experimental results. Therefore, these results imply that our methods are reliable and that the calculations are in accordance with the experimental results.

The cathodic cage plasma nitriding technique is used for thin film deposition. As such, the hollow cathode effect on cage holes is directly related to deposition efficiency. The objective of this work is to study the influence of the cathode length-to-diameter ratio in the deposition of fine copper films on samples placed internally and externally to the cathodic cage, in an argon atmosphere, for 3 h at 420 °C. Compositional, transmittance and morphological characterization of films show copper deposition in all treatments. However, it was observed that substrate temperatures during film deposition influence its morphology. As such, the formation of continuous film on internal samples is observed, whereas external samples show uniformally dispersed nanoparticles as well as the absence of dense film on substrates. As far as the length-to-diameter ratio is concerned, the 1.5 ratio presented the highest deposition efficiency.