•Mg-doped Na2/3Ni1/3Mn2/3O2 samples are obtained by a rapid microwave-calcination.•Highly pure samples are obtained for short annealing times.•Microwave calcination favors the OP4 phase as compared ...to conventional one.•The superior cycling performance of microwave-calcined sample is evidenced at −15 °C.
Microwave calcination is proposed as an alternative to conventional heating in an electric furnace to provide high performance electrodes for sodium-ion batteries. The short annealing time was compatible with the preparation of pure and highly crystalline Mg-doped Na2/3Ni1/3Mn2/3O2 samples. The kinetic response of the electrode samples at three distinct stages of the galvanostatic cycling evidenced the better electrochemical performance of the microwave calcined samples as compared with a reference sample prepared by conventional heating procedures. The higher crystallite size and lower microstrains observed by microwave annealing is crucial to provide a positive electrode with less resistive behavior at high rates, higher Na+ diffusion coefficient, and lower cell internal resistance.
•The study presents a novel biocompatible hybrid coating on medical titanium.•The modified titanium showed low cytotoxicity.•The sol gel dip coating method effectively modified titanium surface.•The ...experimental process followed a rigorous method.•The study provided references for future experimental studies.
The aim of the study was to synthesized organic-inorganic experimental nanocomposite materials via sol–gel dip coating and to characterized its biological response. The sols consist of an inorganic–organic matrix based on ZrO2, TiO2, Li+ and polyethylene glycol (PEG). The obtained hybrid-coated titanium samples have been characterized using atomic force microscope (AFM), Scanning Electronic Microscope (SEM), Energy Dispersive X-Ray Analysis (EDX). Biocompatibility of the hybrid coatings was evaluated by cytotoxicity tests. AFM analysis detailed that the obtained materials were rough nanostructured hybrids. SEM results presented covered surfaces and the presence of particles with different sizes and formats. The EDX data allowed to know the quantitative percentage of the elements present on the surface of the hybrid-coated titanium samples compatible with the sols composition. Cytotoxicity showed that all the hybrid-coated titanium samples had non-cytotoxic effect on target cells, having the groups that included Li+ in the surface higher cellular grown. The sol gel dipcoating method represents a viable alternative to include inorganic and organic elements on titanium and form stable hybrid layers. The modified surfaces of titanium with the experimental materials were rough, presented biocompatible elements and allowed high cellular grown.
In this work, cerium‐ and nickel‐codoped ZnS nanoparticles were obtained by a sonochemical method for 20 min. The nanoparticles were characterized by X‐ray diffraction (XRD), diffuse reflectance ...spectroscopy (DRS), and microscopy electronic transmission (MET). The electrical properties are estimated through I‐V curves and the antimicrobial activity was analyzed against E. coli (gram‐negative) and S. aureus (gram‐positive) bacteria using the diffusion disk methodology. The diffractograms indicate the obtaining of cubic structure ZnS for the pure sample, whereas the doped samples present the cubic and hexagonal structures of the ZnS. The bandgap reduced from 3.60 to 3.52 eV, for pure and codoped samples. I‐V curves indicate an increase in resistivity with doping, being more evident for samples containing cerium. Antimicrobial activity increased as doping occurred, where the codoped sample showed the best results. Even for the low amount of dopant (1 mol%), the antimicrobial activity can be increased by about 50% for the codoped sample, compared to the pure ZnS. Thus, it is known that the doping of ZnS with cerium and nickel provides the stabilization of the hexagonal metastable phase, which acts to restrict electronic mobility and, consequently, improves the antimicrobial response of the material.
Activated carbon materials are derived from carbonaceous sources and used as a technological element for various industrial purposes. These materials are present in most filters (cartridges) in ...personal respiratory protective equipment. Due to this context and to enhance sustainability concepts and human health in the production of materials, this study aimed to produce activated carbon from an abundant agricultural waste in the northeast Brazil through a route that not only favors its simultaneous carbonization and activation but also its thermal neutralization. The precursor biomass was characterized by particle size analysis, a standard testing method for moisture and ash content which were characterized by FRX, CHN, and thermal analysis. The produced activated carbon was characterized by potential of hydrogen (pH), XRD, BET, SEM, TPD by ammonia and UV-Vis analysis. The activated carbons showed yields between 73 and 78%. The morphology varied in function of the biomass interaction with the type and concentration of acid used. The produced samples showed adsorption capacity and selectivity to ammonia gas.
Activated carbon materials are derived from carbonaceous sources and used as a technological element for various industrial purposes. These materials are present in most filters (cartridges) in ...personal respiratory protective equipment. Due to this context and to enhance sustainability concepts and human health in the production of materials, this study aimed to produce activated carbon from an abundant agricultural waste in the northeast Brazil through a route that not only favors its simultaneous carbonization and activation but also its thermal neutralization. The precursor biomass was characterized by particle size analysis, a standard testing method for moisture and ash content which were characterized by FRX, CHN, and thermal analysis. The produced activated carbon was characterized by potential of hydrogen (pH), XRD, BET, SEM, TPD by ammonia and UV-Vis analysis. The activated carbons showed yields between 73 and 78%. The morphology varied in function of the biomass interaction with the type and concentration of acid used. The produced samples showed adsorption capacity and selectivity to ammonia gas.
Rechargeable solid-state batteries have long been considered an attractive power source for a wide variety of applications, and in particular, lithium-ion batteries are emerging as the technology of ...choice for portable electronics. One of the main challenges in the design of these batteries is to ensure that the electrodes maintain their integrity over many discharge-recharge cycles. Fe sub(3) O sub(4) deserves great attention as one of the most important electrode active materials due to its high theoretical capacity (926 mAhg super(- 1)), low cost, being environmental-friendly and naturally abundance in worldwide. A simple strategy to synthesize magnetite nanoparticles (Fe sub(3) O sub(4)) by microwave-assisted hydrothermal method in a short processing time without further treatment is reported. The material obtained was tested as anode active material for lithium ions batteries. Impedance spectroscopy revealed that small differences in cell performance on cycling observed between samples cannot be strictly correlated to cell resistance. A high reversible capacity of 768.5 mAhg super(- 1) at 1C over 50 cycles was demonstrated, suggesting its prospective use as anode material for high power lithium ion batteries.
ABSTRACT The difficulty in the powder reuse favors the study of materials in the form of thin films. ZnO based films have high photocatalytic potential. In this work, ZnO:xSm3+ (x = 0, 1, 2 and 4 ...%mol) thin films were prepared by spin coating method. The resins obtained to manufacture the thin films were prepared by complex polymerization method. The samples were characterized by X-ray diffraction (XRD), atomic force microscopy (AFM), field emission scanning electron microscopy (FE-SEM) and spectroscopy UV-Vis. XRD patterns indicate that doping with 4%Sm forms Sm2O3 as the secondary phase. FE-SEM images of the cross section of thin films indicated a uniform thickness ranging from 354 to 367 nm between samples. The incorporation of Sm3+ ions in the ZnO lattice increases the Egap of the films. The photocatalytic performance of the films was tested with the photodegradation of methylene blue dye. Pure ZnO and ZnO:1%Sm3+ exhibited the best activity in the photodegradation. Thin films of pure ZnO exhibit the best photocatalytic results for the first cycle, but considerably reduce their efficiency with reuse. Sm3+ incorporation, without secondary phase formation, was efficient for the maintenance of the photocatalytic property after 3 cycles.
Crystalline europium-doped indium hydroxide (In(OH) sub(3):Eu) nanostructures were prepared by rapid and efficient Microwave-Assisted Hydrothermal (MAH) method. Nanostructures were obtained at low ...temperature. FE-SEM images confirm that these samples are composed of 3D nanostructures. XRD, optical diffuse reflectance and photoluminescence (PL) measurements were used to characterize the products. Emission spectra of europium-doped indium hydroxide (IH:xEu) samples under excitation (350.7 nm) presented broad band emission regarding the indium hydroxide (IH) matrix and super(5) D sub(0)arrowright super(7) F sub(0), super(5) D sub(0)arrowright super(7) F sub(1), super(5) D sub(0)arrowright super(7) F sub(2), super(5) D sub(0)arrowright super(7) F sub(3) and super(5) D sub(0)arrowright super(7) F sub(4) europium transitions at 582, 596, 618, 653 and 701 nm, respectively. Relative intensities of Eu super(3+) emissions increased as the concentration of this ion increased from 0, 1, 2, 4 and 8 mol %, of Eu super(3+), but the luminescence is drastically quenched for the IH matrix.
Compósitos cerâmicos a base de Al2O3 - Co apresentam propriedades específicas como baixa densidade, alta resistência à oxidação, alta dureza da fase cerâmica com a excelente tenacidade e boa ...trabalhabilidade da fase metálica, bem como, a boa biocompatibilidade de ambas as fases. O compósito alumina – cobalto apresenta ser um material promissor para ser aplicado em biomateriais ou ferramenta de corte. Este trabalho tem como objetivo avaliar o efeito do teor de cobalto na sinterização do compósito Al2O3 – Co. Os pós de partida de alumina e cobalto foram moídos e homogeneizados com teores de 5% e 20% cobalto, em seguida prensados no formato de corpos de prova circular com diâmetro de 5 mm a uma pressão uniaxial de 25 MPa e sinterizados a 1050°C durante 1h com taxa de aquecimento de 10°C/min em forno resistivo. As matérias-primas foram caracterizadas por difração de raios X (DRX), termogravimetria (TG/ DSC) e microscopia eletrônica de varredura (MEV). Os corpos de prova sinterizados foram submetidos a ensaios tecnológicos (AA, PA, MEA) e microscopia eletrônica de varredura. Os resultados evidenciam o efeito significativo do teor de cobalto na sinterização do compósito cerâmico Al2O3–Co, apresentando valores satisfatórios para o compósito Al2O3 – 5% Co.
The aim of this work was to prepare a flexible nanocomposite from ultra-fine titanium oxide (
TiO
2
) growth on carbon fibre via microwave-assisted hydrothermal synthesis (MHS) and to evaluate its ...photocatalytic properties. The
TiO
2
nanoparticles were directly grown on the carbon fibre (CF). Thus, a study comparing the conventional titania coating
vs.
the MHS were performed. The significant layer interaction as a function of the coating method on the visible and dark dye photodegradation performance was observed. Techniques such as X-ray diffraction, electron microscopy (field-emission scanning electron microscope (FESEM)), Raman spectroscopy, among others were used aiming to characterize the different route samples. This study reports a reproducible and single method to manufacture of nanocomposites through the growth of
TiO
2
nanoparticle on CF by MHS that allow controlling the thickness layer. Similar procedure of synthesized nanocomposite could be applied in different chemical compositions to advanced applications, based on the electrochemical nanostructure.
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