Bulletin of Materials Science最新文献

Multicomponent perovskite oxides enable simultaneous tailoring of multiple properties due to their highly tunable chemistries. In this paper, a novel high-entropy perovskite compound (Eu_0.2Gd_0.2Tb_0.2Dy_0.2Ho_0.2)CrO₃ is synthesized by the solid-state reaction method. The X-ray diffraction, scanning electron microscopy images and energy dispersive spectroscopy analysis in combination with the tolerance factor calculation demonstrate that the sample forms a single orthorhombic perovskite with a space group of Pbnm. Second-order antiferromagnetic-paramagnetic phase transition occured at around 4.2 K, confirmed by means of Arrott plot and normalization curve. The maximal magnetic entropy change shifted to the high temperature region with increasing the magnetic field, and reached 11.9 J/(kg·K) in the vicinity of 4 K at a magnetic field of 5 T. The maximum of temperature-averaged entropy change was 10.80 J/(kg·K), indicating that this type of material could be a potential candidate for low temperature magnetic refrigeration (< 20 K).

Naphthoquinones and anthraquinones are widely used in biomedical applications owing to their bioactive properties. Consequently, the development of new methods for producing biomaterials containing these compounds is of significant interest. For efficient nanofiber production, the electroblowing method offers several advantages, as it is practical, easy to operate, and relatively low cost. In this study, nanofibers were produced by electroblowing using model naphthoquinone and anthraquinone compounds, including 2-(allylamino)-3-chloronaphthalene-1,4-dione, 1-chloroanthraquinone, and 1,8-dichloroanthraquinone, at concentrations of 1% and 3% by mass relative to poly(ε-caprolactone). These nanofibers, produced for the first time using the electroblowing technique, were characterized by FTIR, XRD, TGA, DTG, SEM, and EDS analyses. Their cytotoxicity was evaluated using the MTT assay. The results demonstrate that nanofibers incorporating different naphthoquinone and anthraquinone derivatives can be successfully produced as biomaterials using the electroblowing method.

This study aims to compare dual luminescence characteristics of Ba₂Al₂SiO₇ phosphors doped with Ce³⁺ and Dy³⁺ synthesised via a urea-assisted combustion process. X-ray diffraction (XRD) was employed to verify the unaltered polycrystalline structure following doping. Fourier-transform infrared (FTIR) spectroscopy showed that the host structure remains unchanged after doping. Scanning electron microscopy (SEM) showed that the particles were highly agglomerated and were unevenly shaped. The two dopants showed different emission profiles in photoluminescence (PL) measurements: Ce³⁺-activated phosphors showed broad blue emission from 5d→4f transitions following spin-orbit coupling, whereas Dy³⁺-doped samples showed distinctive blue, yellow and weak red emissions from ⁴F_9/2 → ⁶H_13/2 and ⁴F_9/2 → ⁶H_15/2 and ⁴F_9/2 → ⁶H_11/2, respectively. Significant differences in the thermal quenching behaviour were observed in temperature-dependent luminescence studies. Samples doped with Dy³⁺ only lost about 12% of their emission intensity as the temperature rose from 303 to 483 K, while phosphors doped with Ce³⁺ showed a more noticeable decrease of about 31% under the same circumstances. Optical thermometry applications are well suited for Dy³-doped phosphors due to their greater activation energy and quenching temperature (T_Q). The comparison study suggests that Ce³⁺-doped Ba₂Al₂SiO₇ may be a suitable blue-emitting phosphor for solid-state illumination. In comparison, Dy³⁺ doping provides dual functionality with improved temperature-dependent luminous performance. These results show that the development of multifunctional materials suitable for lighting and thermal sensing technologies is made possible by careful dopant selection in barium aluminosilicate matrices.

In this work Debye–Waller factors (DWF) and extended X-ray absorption fine structure (EXAFS) of bcc crystals have been studied based on the advanced anharmonic correlated Einstein model (AACEM). The many-body effect is included in all considered quantities based on a derived anharmonic effective potential including the first shell near-neighbor contributions to the vibrations between absorber and backscatter atoms. The Morse potential is assumed to describe the single-pair atomic interaction. The analytical expressions of temperature-dependent anharmonic DWFs presented in terms of cumulant expansion approach and thermal expansion coefficient have been derived based on quantum thermodynamic perturbation theory. The important advances in the AACEM are performed by calculating the anharmonic contribution to the second cumulant and the application of this AACEM to EXAFS creating an effective method for the accurate structural determination. The numerical results of Mo (bcc) agree well with the experimental values.

The exploration of suitable materials for energy-harvesting applications is a vital requirement in the present era of science and technology. In this work, we examine the structural, magnetic, optical, and mechanical properties, as well as the phonon spectra, of the perovskites CoXO₃ (X = Rh, Ir) using the PBE+TB-mBJ functional implemented within the DFT-based WIEN2k code. In the cubic phase, the calculated lattice constants are 3.8436 Å for CoRhO₃ and 3.8630 Å for CoIrO₃, with lattice angles α = β = γ = 90°. CoRhO₃ exhibits an indirect band gap of 2.29 eV, whereas CoIrO₃, counterintuitively, shows metallic behavior. Total density-of-states analysis reveals that Co and O atoms predominantly contribute to the formation of both valence and conduction bands in these compounds. The elastic constants, derived using the Voigt–Reuss–Hill approximation, yield Young’s modulus values of 13.07 GPa for CoRhO₃ and 13.64 GPa for CoIrO₃. The Poisson’s ratio and elastic anisotropy indicate inherent ductility in both materials, ensuring considerable deformability before fracture. Additionally, the complex dielectric function, refractive index, extinction coefficient, absorption coefficient, optical conductivity, reflectivity, and energy-loss function have been evaluated. The appearance of imaginary frequencies in the phonon dispersion curves suggests that certain vibrational modes are dynamically unstable in the cubic phase. Overall, this comprehensive computational investigation highlights these compounds as promising candidates for future experimental synthesis and practical deployment in optoelectronic and related technologies.

Many companies that manufacture multilayer packaging frequently report failures in continuous inkjet (CIJ) coding, resulting in environmental and economic impacts. This study evaluated the parameters influencing the adhesion of three commonly used CIJ inks, considering the wettability, surface morphology, and chemical composition of the packaging surfaces. Three substrates were investigated: a poly(ethylene terephthalate) (PET) and polyethylene (PE) blend, both with and without corona treatment. The packaging materials were characterized by Fourier transform infrared spectroscopy with attenuated total reflectance (FTIR–ATR), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), contact angle measurements, and surface tension analysis. Ink adhesion was evaluated using the tape peel test in accordance with the FINAT FTM21 standard. The results indicate that PET exhibited favorable surface properties, including higher surface tension (37.4 dynes/cm) and a lower water contact angle (76.8°), resulting in adhesion grade 1 (no ink removal). In contrast, the PE blend showed only a slight increase in surface oxygen content after corona treatment (from 0.46 to 0.80 at%), a modest increase in surface tension (from 29.9 to 31.9 dynes/cm), and a small reduction in water contact angle (from 99.6° to 91.8°). These changes were insufficient to ensure effective ink anchoring, and PE blend samples, both treated and untreated, exhibited severe ink removal (>60%), corresponding to adhesion grade 5. This behavior may be associated with the inefficiency of the corona treatment process employed.

In the present study, we extensively studied the phonon and magnon excitations in nickel oxide (NiO) and Ni/NiO hybrid nanostructures using Raman scattering analyses. The NiO nanostructures were synthesized by facile hydrothermal route and annealed under air and argon (Ar) atmosphere at 800°C. Interestingly, Ar annealed NiO nanostructure shows fine sized particles and the formation of Ni/NiO hybrid. The morphological, structural and phonon vibrational modes of the synthesized nanostructures were investigated by transmission electron microscopy (TEM), grazing incident X-ray diffraction (GIXRD), and Raman scattering techniques. The TEM and GIXRD measurements confirm the formation of face centered cubic phase in NiO and Ni/NiO nanostructures. The surface optical phonon mode is observed in both NiO and Ni/NiO hybrid nanostructure and its theoretical peak positions are estimated using dielectric continuum model. Magnon modes do not appear in Ni/NiO nanostructure, which could be correlated to the reduction in the spin correlated length and super exchange interactions due to the symmetry breaking in the next nearest neighbor of Ni²⁺ ions in the linear atomic chain, Ni²⁺–O²⁻–Ni²⁺ of the crystal lattice.

The spread of COVID-19 led to a huge increase in the generation of polypropylene-based surgical face masks (SFMs) worldwide, leading to landfills and causing severe pollution of resources and the atmosphere when incinerated. In addition, the current treatment methods yield minimal carbon. Therefore, there is a growing need to upcycle waste SFMs into value-added products through safe and environmentally benign processes. In this study, waste SFMs were upcycled into activated carbon (AC) through a series of processes including sulfonation, pre-carbonization and activation with KOH at varying temperatures. The surface functionalities and textural properties of the resulting AC samples were thoroughly characterized using vibrational spectroscopy, N₂ sorption and microscopic studies. As the activation temperature increased, the porosity and surface area of the AC also increased. Notably, AC derived from SFMs upcycled at an activation temperature of 950°C (AC-950) exhibits an exceptionally high surface area of 2163 m² g⁻¹, promising oxygen reduction reaction (ORR) activity (high onset potential of 932 mV and limiting current density of 16.6 mA cm⁻²), comparable to the benchmark Pt/C electrocatalyst. In addition, it displays a commendable supercapacitor behaviour (specific capacitance of 236 F g⁻¹ at 1 A g⁻¹, good rate retention and cycle-life).

Graphical abstract

This study presents an analysis of the Sprott (Phys. Lett. A 378 1361–1363, 2014) chaotic patterned electromagnetic absorber, which exhibits a broadband band absorption rate in the range of 2–20 GHz. The application studies commenced with an analysis of the parameters of the Sprott (2014) chaotic attractor, resulting in the generation of three-dimensional plane images. Given that the z-plane has a standard thickness of 0.035 mm in the electromagnetic absorber to be designed, the three-dimensional images obtained were processed with various iterations in the Julia fractal and transformed into two-dimensional patterns. These patterns were then examined in the simulation environment to assess the electromagnetic absorption of the patterns. In the design of the electromagnetic absorber, the chaotic patterns have been defined as copper with a standard thickness of 0.035 mm, and Magtrex 555, which exhibits frequency-dependent permeability, was selected as the substrate. In order to achieve the maximum absorption value, the back layer of the electromagnetic absorber structure was coated with copper sheet. This study examines the impact of the design parameters, including substrate thickness, absorber size, and substrate type, on the absorption rate of the electromagnetic absorber through a parametric analysis. The operational methodology of the proposed structure was elucidated through an examination of the electric field and surface current distributions at various resonant frequencies. The characteristics of the Sprott (2014) chaotic patterned electromagnetic absorber were subjected to a comprehensive analysis, which reveals its potential for integration into a multitude of contemporary applications. Notably, this study marks the inaugural application of the Sprott (2014) chaotic method in the design and optimization of a metamaterial absorber, thereby contributing a novel perspective to the existing literature on the subject.