Bulletin of Materials Science最新文献

In this study, we have hydrothermally synthesized Nb₂O₅ nanorods of various dimensions at different reaction times. These synthesized samples were physio-chemically characterized by UV-visible, XRD, FESEM, HRTEM and XPS techniques. The absorbance spectrum has shown blue-shift than the bulk counterpart, whereas XRD and XPS confirm the formation of Nb₂O₅. FESEM and HRTEM reveal the formation of rod-like structures. The annealing temperature affects the surface porosity of the samples as the porous rod like Nb₂O₅ formed at higher annealing temperature. Further, the Nb₂O₅ was used as photoanode material in dye-sensitized solar cells and characterized by different photovoltaic characterization parameters (photocurrent density–voltage (J–V) curve, IPCE, FF and cell efficiency). The enhanced photovoltaic parameters were obtained for NB-2 with photocurrent value of 8.40 mA cm⁻² and efficiency (η) of 3.43%. This enhanced performance is the result of high surface roughness and porosity, which assisted in improving the efficiency, dye loading and better electronic conduction pathway. Electrochemical impedance spectroscopy (EIS) was studied to understand the charge transfer and recombination at Nb₂O₅|dye|electrolyte interfaces.

Electro-discharge layering (EDL) is a coating technique, used for fabricating wear and corrosion resistance layer on the parts used in automobile, biomedical and structural applications. Eventhough, selecting the suitable parameters and levels in EDL process is difficult to attain better coating characteristics. We have studied the prediction and effect of process parameters on EDL of magnesium alloy using response surface methodology (RSM)-assisted feed forward back propagation artificial neural network (ANN). In this work, WC–Cu composite coating was deposited on AZ31B magnesium alloy using EDL viz. compaction pressure (CP), discharge current (DC) and pulse on time (PT). Influence of process parameters on electrode deposition rate (EDR) and coating roughness (CR) during EDL of magnesium alloys is studied. It was revealed that the correlation between the experimental values of RSM and predicted values of ANN was 0.991, which is closely to the working limit. Therefore, it was agreed that the established ANN model is suitable for predicting the EDR and CR. Furthermore, effect of parameters on CR and EDR are studied with support of mean effect plots generated by RSM tool. It was studied that the CR and EDR will increase, as increase in DC and PT at processing with low compaction pressured electrode. Conversely, it decreases with increase in CP of the electrode. Mechanism of coating, such as craters and globules were identified in the surface coated with higher DC and PT, resulting in higher surface roughness values.

A solid-state refrigerator device has the potential to overcome the use of greenhouse effect-related gases or hazardous chemicals. Most of these devices work on the basis of magnetocaloric effect (MCE). Ce(Fe_0.975Cr_0.025)₂ is an engrossing material to study MCE originating from paramagnetic (PM)–ferromagnetic (FM; second-order) transition and FM–antiferromagnetic (first-order) transition. In the present work, the MCE of Ce(Fe_0.975Cr_0.025)₂ compound, prepared in Arc melting in an argon atmosphere, has been studied. Magnetic entropy change (∆_SM) and the relative cooling power have been calculated from the M–H curves to characterize the MCE. Direct and inverse MCE are found to be linked with two different magnetic transitions in this compound.

This research focuses on the fabrication of transparent conducting films of cadmium oxide (CdO) and cadmium oxide doped with chromium, utilizing a straightforward chemical spray pyrolysis technique. The investigation delves into the characteristics of these films by employing various methods, including X-ray diffraction, scanning electron microscopy, UV–visible transmittance analysis, Hall measurements and gas-sensing experiments. The study comprehensively examines the structural, morphological, optical, electrical and sensing properties in connection with different levels of chromium doping. The findings reveal that both the pristine and chromium-doped CdO films exhibit a polycrystalline cubic structure, as indicated by the X-ray diffraction analysis. Alterations in the surface microstructure, caused by varying chromium (Cr) doping concentrations, are evident in SEM images, displaying the presence of semi-spherical nanoparticles. The optical transmittance of the films exhibits a non-linear trend, decreasing initially and then increasing as the Cr concentration rises, reaching its peak at a 2.60 eV bandgap for films doped with 7 wt% Cr. Hall measurements confirm that all films exhibit n-type semiconductor behaviour. The CdO film doped with 7 wt% Cr exhibits a minimum resistivity of 0.427 × 10⁻² Ω.cm and a carrier concentration of 2 × 1018 cm⁻³. Gas-sensing experiments conducted with ammonia indicate a maximum response of 26% at an operating temperature of 300°C for the 7 wt% Cr-doped CdO sample, which also displays faster response and recovery times.

Myocardial infarction (MI) is one of the major diseases that threaten human life and health. The construction of cardiac patch by tissue engineering method and biomaterials is a promising way to treat MI clinically by improving electromechanical signal transduction in MI area. A highly conductive electrospun fibre-engineered biomedical patch with porous structure, mechanical support and conductive property was prepared by poly(lactic-co-glycolic acid) (PLGA), polyaniline (PANI), graphene oxide (GO) and multi-walled carbon nanotubes (MWCNT). PLGA, PLGA/MWCNT, PLGA/GO electrospinning fibre membrane substrates were prepared first and then in-situ polymerization of aniline (ANI) to form PANI/PLGA and PANI/PLGA/MWCNT fibre conductive patches. PLGA-blended fibre patch had a smooth fibre surface and an uniform fibre diameter, porous structure, fibre parallel arrangement, in which PLGA/MWCNT had larger ultimate strength and Young’s modulus. When the ANI concentration was 0.4 mol l⁻¹, electrical conductivity reached the maximum value, and the electrical conductivity of PANI/PLGA fibre patch was significantly larger than that of PANI/PLGA/MWCNT fibre patch as the ANI concentration increased, which were 1.56 × 10⁻² and 6.06 × 10⁻³ S cm⁻¹, respectively. Highly conductive fibre membrane-engineered biomedical patch had excellent electrical and thermal stability, and improved signal transduction, with porous structure and mechanical support for potential MI repair.

The aim of this research work was to investigate the impact of various process parameters on the particle size of Febuxostat (FEB) nanocrystals using response surface methodology. The continuous microchannel nanoprecipitation technique was employed to produce FEB nanoparticles with poloxamer 407 as the polymer. Initially, a Plackett-Burman design was conducted to identify the key variables that significantly influenced the nanoprecipitation process using microfluidic techniques. The independent variables considered were solvent flow rate (X1, ml h⁻¹), solvent-to-antisolvent ratio (X2), microchannel length (X3, cm), drug concentration (X4, mg ml⁻¹) and polymer-to-drug ratio (X5), while the dependent variable was the particle size (Y1, nm) of the nanocrystals. Among these variables, microchannel length (X3), drug concentration (X4) and polymer-to-drug ratio (X5) showed significant influence on the particle size of nanocrystals (P < 0.001). The minimum particle size observed was 303.5 ± 2.33 nm, with a polydispersity index value of 0.159 ± 0.03, achieved at a solvent-to-antisolvent ratio of 1:2, a polymer-to-drug ratio of 1:1, a microchannel length of 50 cm and a solvent flow rate of 50 ml h⁻¹. Subsequently, a Box-Behnken design was applied to the variables identified as significant in the Plackett-Burman design, focusing on the particle size. The results indicated that microchannel length, polymer-to-drug ratio and drug concentration had a considerable impact on the particle size of FEB. Overall, the microfluidic nanoprecipitation technique demonstrated great potential as an effective technology for reducing the size of drug crystals to the nanoscale.