Bulletin of Materials Science最新文献

To achieve high performance in perovskite solar cells (PSCs), it is very vital to engineer the recombination and extraction of the hole–electron pairs at the electron transport layer (ETL)/perovskite interface. In this research, the main idea is to improve the photovoltaic performance of the cells by modifying the compact ETL surface (≈50 nm thick) by inserting a <10 nm thick ultra-thin layer (UTL) of metal oxide. For this purpose, all types of single layer and bilayer structured ETLs of TiO₂, SnO₂ and WO₃, i.e., three common metal oxide electron transport materials in PSCs, were fabricated using the reproducible and industry-compatible radio-frequency sputtering method and their function as ETLs was then compared. These ETLs and cells were characterized for structural and electrical properties by FESEM, XRD, Mott–Schottky analysis, UV–Vis spectroscopy and J–V measurements. It was found that a significant increase in cell efficiency is achieved due to more efficient energy band alignment using the bilayer structures of TiO₂/WO₃-UTL, SnO₂/WO₃-UTL and TiO₂/SnO₂-UTL. Conversely, reduced efficiency is observed when using their inverted structures, namely WO₃/TiO₂-UTL, WO₃/SnO₂-UTL and SnO₂/TiO₂-UTL. These results suggest a simple and promising strategy to increase the efficiency of photovoltaic devices.

In this research, the role of B₄C-reinforcing particles on the corrosion behaviour of Al5083/B₄C nanocomposite has been investigated. Al/B₄C nanocomposite powder with weight percentages of 3 and 7 of reinforcing phase was prepared by mechanical milling method. The resulting powder was initially hot-pressed and then hot-extruded. The microstructure of the sample was studied using scanning electron microscopy and their corrosion behaviour was studied using potentiodynamic polarization and scanning electrochemical impedance spectroscopy methods in different immersion time intervals. The results showed a uniform distribution of reinforcing particles and also the scattering of intermetallic particles at the surface of the samples. However, increasing the content of B₄C particles in the composite samples enhances the cathodic and anodic reactions by increasing the content of intermetallic particles as cathodic sites on the surface, so that higher corrosion current density is observed in the composite samples with 7 wt% B₄C. Finally, it was concluded that increasing the value of B₄C decreases the corrosion resistance of the B₄C-reinforced composite samples in sodium chloride solution, which makes it unsuitable in marine applications.

Ba_0.95Sr_0.05Ca₅Ti₂Nb₈O₃₀ sample was prepared by solid-state reaction technique to investigate structural, optical, magnetic and dielectric properties via performing different characterizations. XRD reveals the orthorhombic structure with Pbcn space group along with Rietveld refinement. Grain size of the bulk sample was carried out by SEM, which is 1.25μm. Then, microstructural correlated with optical by means of Raman, FTIR and PL spectroscopies. Raman studies reveal the presence of different modes along with band assignments. FTIR and PL studies reveal the bonding modes of A- and B-site atoms, which give the energy band gap around 2.969, 2.441 and 2.012 eV for different bond contributions. The magnetic property was carried out by VSM. The dielectric properties, as a function of frequency and temperature, were carried out and reveal that the bulk sample can be used as storage devices. The modulus spectroscopy was calculated from dielectric studies to analyse electrical properties.

The present investigation deals with the detailed analysis of opto-structural, morphological, electrical properties and photoelectrochemical cell performances of thermally evaporated Ag_xBi_2−xS_3−y thin film prepared for various x and y values (x = y = 0, 0.25, 0.50, 0.75 and 1). The cubic-structured AgBiS₂ along with orthorhombic-structured Bi₂S₃ as confirmed from X-ray diffraction (XRD) analysis. The Ag_xBi_2−xS_3−y (x = y = 0–1) films showed higher optical absorption coefficient (10⁵ cm⁻¹) in the visible region and band gap values were found to be decreased from 2.08 to 1.35 eV. Scanning electron microscope (SEM) images have visualized the uniform distribution of spherical particles. Carrier concentration of the films are better than x = y = 0 as observed from Mott–Schottky plots. The FTO/Ag_xBi_2−xS_3−y (x = y = 1) photoelectrochemical cell yields the photoconversion efficiency (PCE) of 7.03%.

The viscosity of shear-thickened fluid (STF) undergoes a rapid increase under high loading, resulting in the formation of a solid-like structure. Importantly, the viscosity of STF returns to its liquid state instantly when the load is removed. This liquid–solid transformation process allows STF to effectively absorb external energy, making it highly suitable for applications in energy absorption. This article provides an overview of the current research status of STFs based on relevant literature. Firstly, the shear-thickening mechanism of STFs is introduced. Then, the factors that influence the rheological properties of STFs are summarized based on studies that have examined changes in rheological properties. Finally, this review summarizes the challenges that may be encountered in the application of STF and also provides corresponding research directions for future research.

This research focuses on the development of carbide-free nanostructured bainitic steel through the process of austempering at 250°C. The selected steels are also patented at 550°C, to get fine pearlitic structure. In austempered steels, microscopic analyses encompassing optical, scanning, transmission electron microscopy and X-ray diffraction revealed the presence of nanoscale bainite, filmy and blocky austenite. In contrast, lamellar pearlite was observed in the patented steels. With increase in the austempering duration, the extent of bainite improved, while the volume percentage of blocky retained austenite (RA) decreased. The tribological performance of high-carbon bainitic steels is compared with patented one of same composition against a tungsten-carbide counter disc. The specific wear rate as well as coefficient of friction decreases with rise in load from 10 to 50 N. The hardening volume of B15VA-1 sample is greater than that of B15VA-2 and P15VA, and it is mainly due to the transformation of blocky RA to strain-induced martensite. The bainitic pins with higher hardness exhibited superior tribological response than the pearlitic ones. SEM analysis of worn surfaces confirmed that at lower load (10 N), abrasive wear occurs, but at higher load (50 N), wear mechanism changes to adhesive along with abrasive in bainitic steel and oxidative wear along with adhesive and abrasive wear in pearlitic steel.

A highly sensitive hydrogen gas sensor operating at room temperature made of macroporous silicon (MPS) coated with a thin NiO film was developed. MPS layer was shaped by electrochemical anodization on an n-type Si surface. Thereafter, p-type NiO film was deposited onto the MPS surface by electrodeposition method. The morphology of the NiO/MPS sample was characterized by scanning electron microscopy. Al electrical contacts for further measurements were deposited onto the structure NiO/MPS by evaporation technique under vacuum. Gas sensing performances were measured to various H₂ concentrations ranging from 122 to 1342 ppm at room temperature. The results showed that the electrical behaviour of synthesized NiO/MPS sensor is similar to that of a diode, which can be used to detect H₂ gas at low concentrations, which reveals high sensitivity, fast response and recovery times working at room temperature.

Graphical Abstract

MgKPO₄·6H₂O (magnesium potassium phosphate-based cement; MKP) is an environment friendly alternative to Portland cement with potential applications in environmental remediation and radioactive nuclear waste management, particularly in the context of β-emitting Cs and Sr immobilizations. Thus, investigation of the radiation effects and temperature due to decay heat in such material is of prime importance. In this study, MgKPO₄·6H₂O powders were synthesized and subsequently annealed at 1273 K for 2 h under ambient atmosphere to form MgKPO₄. The synthesized and annealed MKP specimens were irradiated under ambient conditions with 10-MeV electron beam up to imparted doses of 20 MGy. XRD results reveal the formation of amorphous fraction in irradiated MgKPO₄·6H₂O, while the annealed MKP specimens exhibit good radiation stability without amorphization. The annealed specimens also indicated good thermal stability when compared to as-prepared MgKPO₄·6H₂O specimen both in pristine and irradiated conditions. Vibrational spectroscopic results confirm that the radiation effect resulted in distortion/removal of structural water and formation of radiolysis products in MgKPO₄·6H₂O.

This study presents the interfacial behaviour of benzoylated cellulose of different wettability from melon and moringa pods waste using Pickering emulsions systems. The benzoylated cellulose was prepared in an aqueous alkaline medium using benzoyl chloride as a modifying agent and characterized by X-ray diffraction, thermogravimetric analysis, Fourier transform infrared spectroscopy and scanning electron microscopy (SEM). The X-ray diffraction showed that crystallinity of cellulose from moringa and melon are 67.47 and 70.20%, respectively. The functionalized derivatives are thermally stable than the native counterpart. The SEM revealed that isolated cellulose suffered surface degradation upon functionalization as a result of the repeated collision between reactants. The wetting properties of the cellulose can be controlled by using different quantities of modifying agents, and the emulsions stability depend on the wettability of the emulsifiers. The higher stability recorded for the emulsions stabilized by benzoylated cellulose from moringa pod waste revealed that cellulose wettability depends on the sources.