RESUMEN
This paper reports a method for the fabrication of mineral-like SrMoO4 ceramics with a powellite structure, which is promising for the immobilization of the high-energy 90Sr radioisotope. The reported method is based on the solid-phase "in situ" interaction between SrO and MoO3 oxides initiated under spark plasma sintering (SPS) conditions. Dilatometry, XRD, SEM, and EDX methods were used to investigate the consolidation dynamics, phase formation, and structural changes in the reactive powder blend and sintered ceramics. The temperature conditions for SrMoO4 formation under SPS were determined, yielding ceramics with a relative density of 84.0-96.3%, Vickers microhardness of 157-295 HV, and compressive strength of 54-331 MPa. Ceramic samples demonstrate a low Sr leaching rate of 10-6 g/cm2·day, indicating a rather high hydrolytic stability and meeting the requirements of GOST R 50926-96 imposed on solid radioactive wastes. The results presented here show a wide range of prospects for the application of ceramic matrixes with the mineral-like composition studied here to radioactive waste processing and radioisotope manufacturing.
RESUMEN
At present, climate change, urbanization and globalization are the main factors that affect water quality, the primary vehicle for the translocation and permanence of emerging pollutants, resulting in a danger to human health and the environment. The scheelite-type compounds have been investigated owing to their interesting photocatalytic properties in water purification trough the removal of different organic and inorganic pollutants. In this article a method solid state for doping of bismuth(III) in systems Sr1-3xBi2xΦxMoO4 with (0 ≤ x ≤ 0.225) were obtained and, likewise its pelletizing process. Subsequently, these new materials were spectroscopically characterized with photocatalytic properties and finally is describe its development as oxidant against Rhodamine B. This work can be used for the synthesis of new Bi-doped strontium molybdates, which the best photochemical properties are chosen and, in turn, it is experimentally shown how can favor its absorption in the visible region. These electronic properties can be used in near studies, for to compressive the role of bismuth(III) in sheelite as photocatalyst and, to implement its use in the degradation of persistent pollutants that affect the world's water resources.â¢The doping of bismuth(III) for systems Sr1-3xBi2xΦxMoO4 modified the GAP absorption and this catalytic properties using this new solid state method.â¢The degradation of Rhodamine B for systems Sr1-3xBi2xΦxMoO4 as case study using of this methodology allows multiple applications associated with climate change such as: the degradation of emerging pollutants and the sensitization of semiconductors with solar claims.â¢The role of bismuth(III) in these systems can be harnessed to design similar materials with photocatalytic properties.
RESUMEN
X-ray photoelectron spectroscopy was used to study the direct synthesis of strontium and molybdenum oxide thin films deposited by multitarget reactive magnetron sputtering (MT-RMS). Sr and Mo targets with a purity of 99.9% and 99.5%, respectively, were co-sputtered in an argon-oxygen gas mixture. The chamber was provided with an oxygen background flow plus an additional controlled oxygen supply to each of the targets. We demonstrate that variation in the power applied to the Mo target during MT-RMS enables the production of strontium and molybdenum oxide films with variable concentrations of Mo atoms. Both molybdenum and strontium were found in the oxidized state, and no metallic peaks were detected. The deconvoluted high-resolution XPS spectra of molybdenum revealed the presence of several Mo 3d peaks, which indicates molybdenum bonds in a lower valence state. Contrary to the Mo spectra, the high-resolution strontium Sr 3d spectra for the same samples were very similar, and no additional peaks were detected.
RESUMEN
Vanadium-doped strontium molybdate (SVM) has been investigated as a potential anode material for solid oxide fuel cells due to its high electronic conductivity of about 1000 S cm-1 at 800 °C in reducing atmospheres. In this work, NiO is introduced to SVM with the B-site excess design to induce in situ growth of Ni nanoparticles in the anodic operational conditions. The Ni particles are exsolved from the parent oxide phase as clearly demonstrated with various techniques including X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscopy. The exsolved Ni nanoparticles significantly boost the electrocatalytic activity toward fuel oxidation reaction, improving the peak power density by 160% from 0.21 to 0.56 W cm-2 at 800 °C when using H2 as the fuel, meanwhile reducing the total interfacial polarization resistance by 56% from 0.81 to 0.36 Ω cm2. The Ni-exsolved SVM anode also shows excellent catalytic activity toward H2S-containing and hydrocarbon fuels, providing peak power densities of 0.43, 0.36, and 0.22 W cm-2 at 800 °C for H2-50 ppm H2S, syngas, and ethanol, respectively. In addition, the cell with the Ni-exsolved SVM anode presents a stable power output, indicating that the Ni-SVM is a potential SOFC anode electrocatalyst for various fuels.