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Developments in the field of materials science are contributing to providing solutions for the recycling of industrial residues to develop new materials. Such approaches generate new products and provide optimal alternatives to the final disposal of different types of industrial wastes. This research focused on identifying and characterizing slag, fly ash, and glass cullet from the Boyacá region in Colombia as raw materials for producing glass-ceramics, with the innovative aspect of the use of these three residues without the addition of nucleating agents to produce the glass-ceramics. To characterize the starting materials, X-ray diffraction (XRD), X-ray fluorescence (XRF), and Scanning Electron Microscopy (SEM) techniques were used. The results were used to evaluate the best conditions to produce mixtures of the three waste components and to determine the specific compositions of glass-ceramics to achieve products with attractive technical properties for potential industrial applications. The proposed mixtures were based on three compositions: Mixture 1, 2, and 3. The materials were obtained through thermal treatment at 1200 °C in a tubular furnace in accordance with the results of a comprehensive characterization using thermal analysis. The microstructure, thermal stability, and structural characteristics of the samples were examined through SEM, differential thermal analysis (DTA), and XRD analyses, which showed that the main crystalline phases were diopside and anorthite, with a small amount of enstatite and gehlenite. The obtained glass-ceramics showed properties of technical significance for structural applications.

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The coating of polymeric substrate polyetheretherketone (PEEK) with silver nanoparticles (AgNPs) was carried out by a wet chemical route at room temperature. The coating process was developed from the Tollens reagent and D-glucose as reducing agent. The resulting composite exhibited antimicrobial activity. The PEEK films were coated with a single layer and two layers of silver nanoparticles in various concentrations. The crystallographic properties of the polymer and the silver nanoparticles were analyzed by X-ray diffraction (XRD). Fourier transform infrared spectra (FTIR) show the interaction between the silver nanoparticles with the polymeric substrate. Transmission electron microscope (TEM) images confirmed the obtaining of metallic nanoparticles with average sizes of 25 nm. It was possible to estimate the amount of silver deposited on PEEK with the help of thermogravimetric analysis. The morphology and shape of the AgNPs uniformly deposited on the PEEK films was ascertained by the techniques of scanning electron microscopy (SEM) and atomic force microscopy (AFM), evidencing the increase in the amount of silver by increasing the concentration of the metal precursor. Finally, the antibacterial activity of the films coated with Ag in Escherichia coli, Serratia marcescens and Bacillus licheniformis was evaluated, evidencing that the concentration of silver is crucial in the cellular replication of the bacteria.

In the present work we report the synthesis of mixed ferrites doped with Co2+, Cu2+ and Ba2+ cations, using citrate sol–gel combustion route in air atmosphere, at 950 °C for 3 hours, produced substituted M-type barium ferrites powders particles with crystallite sizes varying between 145 and 155 nm. The percentages of yield obtained were on average 42%. The synthesized ferrites were characterized by techniques such as powder X-ray diffraction, evidencing the formation of M-type barium hexaferrite and copper and cobalt substituted M-type barium ferrite with hematite in smaller proportion. The possible growth of M-type barium ferrite with copper and cobalt may be due to a larger size of the cobalt atom with respect to copper and that a higher proportion of cobalt salt was used in the synthesis route. Increase in the metal ion substituted content leads to a decrease in the lattice strain and may be responsible for an increase in the crystallite size because greater tensile strain leads to elongation of the particles. The particle size of the synthesized ferrites differs significantly when they are doped, with Ferrite doped with copper having the smallest particle size compared to Ferrite doped with cobalt. We also performed spectroscopic analyses, RAMAN that showed, the substitution of cooper or cobalt in the M-type barium ferrite powders particle leads to a minor intensity of resonance band when compared with the parent compound and the differences between Fe3+, Cu2+ and Co2+ ions in a tetrahedral coordination is their ionic radii. The increase in the ionic radii causes a local distortion and vibrational bands of distorted polyhedra in substituted M-type barium ferrites. The chemical composition of this sample was determined as Ba1.0Fe11.83O19.22, Ba1.0Co1.02Fe11.01O18.35 and Ba1.02Cu0.56Fe11.35O18.26 using an AAS device. Both are very close to the theoretical formula. The influence of the synthesized ferrite samples was explored in the ozonation of a dye of unknown chemical structure. The effect was evidenced by visible ultraviolet spectroscopy technique. The results obtained show that the ink could be decolorized by applying oxidation by ozonation, however, when substituted M-type barium ferrite is added, the discoloration increases when this is doped with copper and cobalt, being higher using this last ferrite. The degradation process by ozonation presented in this work, carried out in the presence of copper and cobalt substituted M-type barium ferrites, would constitute an example of technology for the environment.

Polyaniline (PANI) has recently gained great attention due to its outstanding electrical properties and ease of processability; these characteristics make it ideal for the manufacturing of polymer blends. In this study, the processing and piezoresistive characterization of polymer composites resulting from the blend of PANI with ultra-high molecular weight polyethylene (UHMWPE) in different weight percentages (wt %) is reported. The PANI/UHMWPE composites were uniformly homogenized by mechanical mixing and the pellets were manufactured by compression molding. A total of four pellets were manufactured, with PANI percentages of 20, 25, 30 and 35 wt %. Fourier-transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), differential thermal analysis (DTA), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) were used to confirm the effective distribution of PANI and UHMWPE particles in the pellets. A piezoresistive characterization was performed on the basis of compressive forces at different voltages; it was found that the error metrics of hysteresis and drift were influenced by the operating voltage. In general, larger voltages lowered the error metrics, but a reduction in sensor sensitivity came along with voltage increments. In an attempt to explain such a phenomenon, the authors developed a microscopic model for the piezoresistive response of PANI composites, aiming towards a broader usage of PANI composites in strain/stress sensing applications as an alternative to carbonaceous materials.

This paper describes the preparation of La 0.75 Sr 0.25 Cr 0.2 Fe 0.8 O 3 perovskite oxide, using a polymerization-combustion route, to obtain materials for potential applications like electrodes in solid oxide fuel cells (SOFC). For such purpose, initially the solid precursor was characterized by FT-IR spectroscopy and thermal analysis (TGA-DTA), showing the obtention of polymeric citrate precursors. The thermal analysis (TGA-DTA), X-ray diffraction (XRD) and scanning electronic microscopy (SEM), provides information about the formation of a perovskite phase, while the texture, relief and roughness found are characteristic of the method of synthesis used. The size of crystallites, calculated using the Scherrer calculator software and transmission electron microscopy (TEM), confirmed the presence of nanometric crystallites (< 41.0 nm), whereas the chemical composition and crystallographic structure, indicating a high correlation with respect to proposed system, which was confirmed by X-ray fluorescence (XRF), energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). Finally the electrical characterization by impedance spectroscopy (IS), determined the capacitance and resistance of the system in order to provide information related to the concentration of charge carriers and the diffusion rate of ions in the material a high conductivity values, related to semiconductor behavior for potential applications.

This paper reports the synthesis and characterization of a lanthanum-barium-copper oxide, based on a LaBa 2 Cu 3 O 7 system, using a wet chemical route that enables the combustion-polymerization of citrate species, in order to generate materials with enhanced surface and textural and morphological properties for potential applications. The synthesized precursor in a form of a coordination complex was characterized by Fourier transform infrared spectroscopy (FTIR) analysis in order to evaluate the formation of homogeneous and soluble citrate species as intermediates of reaction. The morphological and structural characterizations were performed over calcined material with X-ray diffraction (XRD) and electron microscopy (scanning electron microscopy (SEM)-transmission electron microscopy (TEM)) analyses, confirming the obtention of an orthorhombic crystalline phase type Pmmm (47) in the nanometric range ≈8.9 nm. Analyses of the ceramic oxide by Raman spectroscopy and X-ray photoelectron Pátria, 156, Niterói, 24210-240, Brazil spectroscopy (XPS) allowed to perform qualitative and quantitative assessments of the material composition, showing that the final oxide is closely related to the desired composition, discarding the presence of carbonaceous residues of the synthesis process.