RESUMEN
The effect of the morphology and content of zinc oxide nanoparticles (ZnO-NPs) on the physicochemical, mechanical, and gas transport properties of the polyurethane (PU) mixed matrix membranes (MMMs) with respect to CO2 recovery from CH4, O2, and N2 was studied. The MMMs based on PU with spherical and rod-shaped ZnO-NPs at various loadings, namely, 0.05, 0.1, 0.5, 1, and 2 wt. %, were prepared with membrane density control and studied using AFM, wettability measurements, surface free energy calculation, gas separation and mechanical testing. To evaluate the resistance of the ZnO-NPs to agglomeration in the polymer solutions, zeta potential was determined. The ZnO-NPs with average cross sectional size of 30 nm were obtained by plasma-enhanced chemical vapor deposition (PECVD) from elemental high-purity zinc in a zinc-oxygen-hydrogen plasma-forming gas mixture. It was established that the spherical ZnO-NPs are promising to improve the gas performance of PU-based MMMs for CO2 recovery from natural gas, while the rod-shaped NPs better demonstrate their potential in capturing CO2 in flue gases.
RESUMEN
Zinc oxide nanoparticles were obtained by plasma-enhanced chemical vapor deposition (PECVD) under optical emission spectrometry control from elemental high-purity zinc in a zinc-oxygen-hydrogen plasma-forming gas mixture with varying deposition parameters: a zinc source temperature, and a reactor temperature in a deposition zone. The size and morphological parameters of the zinc oxide nanopowders, structural properties, and homogeneity were studied. The study was carried out with use of methods such as scanning electron microscopy, X-ray structural analysis, and Raman spectroscopy, as well as statistical methods for processing and analyzing experimental data. It was established that to obtain zinc oxide nanoparticles with a given size and morphological characteristics using PECVD, it is necessary (1) to increase the zinc source temperature to synthesize more elongated structures in one direction (and vice versa), and (2) to decrease the reactor temperature in the deposition zone to reduce the transverse size of the deposited structures (and vice versa), taking into account that at relatively low temperatures instead of powder structures, films can form.
RESUMEN
In-situ Optical Emission Spectroscopy (OES) combined with quantum chemical calculations was used as a powerful tool to find out the exited reactive species existing in plasma discharge during the process of lead sulfide chalcogenide materials deposition. Low temperature nonequilibrium RF (40.68 MHz) plasma at low pressure (0.1 Torr) was employed for initiation of chemical interaction between precursors in the gas phase. Only high-pure elements were utilized as the initial substances. The ration between starting materials in the gas phase and power included into the plasma discharge were the variables. The mechanism of the plasma-chemical reaction was assumed and discussed. The stoichiometry and morphology of the surface of the as-deposited materials were studied by different analytical techniques.
RESUMEN
AsxTe100-x amorphous films of different chemical content were prepared by Plasma-Enhanced Chemical Vapor Deposition (PECVD). For the first time the optical properties of As-Te chalcogenide materials have been measured in UV-VIS-IR ranges (from 0.2 to 25µm) for a very wide range of chemical compositions (20-80at.% As). As-Te films have been tuned from 0.80 to 1.10eV. The IR results obtained have been juxtaposed with the Raman spectroscopy findings to establish the correlation between optical and structural properties of the materials developed. Reversible and irreversible changes in the phase composition of the As-Te films under annealing of the surface by laser irradiation have been demonstrated and studied. In order to determine the potential areas of application of the prepared As-Te films the thermal and photo sensitivity has been also investigated.
RESUMEN
AsS chalcogenide films, where As content is 60-40at.%, have been prepared via a RF non-equilibrium low-temperature argon plasma discharge, using volatile As and S as the precursors. Optical properties of the films were studied in UV-visible-NIR region in the range from 0.2 to 2.5µm. Infrared and Raman spectroscopy have been employed for the elucidation of the molecular structure of the newly developed material. It was established that PECVD films possess a higher degree of transparency (up to 80%) and a wider transparency window (>20µm) in comparison with the "usual" AsS thin films, prepared by different thermal methods, which is highly advantageous for certain applications.