Bulletin of Materials Science最新文献

The present research work approaches the removal of fluoride from contaminated water using an eco-friendly novel iron-based polyaniline nano-composite (PAn) in a batch mode method. The fluoride adsorption efficiency was studied with variation of parameters like initial fluoride concentration 10-20 mg L⁻¹, contact time 10-90 min, variation of adsorbent dose 0.1−1 g, temperature 25°, 30° and 40°C, pH 2-12 and presence of competing ions at 25°, 30° and 40°C and was optimised with artificial neural network model (ANN). The experimented adsorption data was best fitted to Langmuir adsorption isotherm with maximum adsorption capacity of 89.41 mg g⁻¹ at 40°C. The adsorption kinetics followed the pseudo second order reaction. The thermodynamics studies indicate that the adsorption process was spontaneous and endothermic in nature. The maximum fluoride removal was found to be 91% with good agreement to the results predicted by ANN model (structure 5-10-1). The PAn nano-composite can be used maximum of up to four cycles for defluoridation of drinking water. To determine the adhesion of fluoride on the PAn nano composite, the material was characterized using different instrumental analyses like SEM EDS, BET, XRD and FTIR. The FePAn nanocomposite can be used maximum up to four cycles for defluoridation of drinking water.

Magnetodielectric composites _xPb_0.8Nd_0.2(Zr_0.52Ti_0.48)O₃-_1-xSrFe₁₂O₁₉ (x = 0.50, 0.52, 0.54, 0.56, 0.58) have been reported. Structural phase analysis confirmed successful synthesis of reported ceramic composites. Magnetic hysteresis reveals magnetic ordering in prepared composites whereas micrographs strongly support dielectric permittivity. All prepared composites exhibit high values of dielectric constant. Strong magnetodielectric response (MDR) is observed in low frequency region which goes on decreasing with frequency, indicating Maxwell-Wagner interfacial phenomenon in the studied composites. The MDR extends to higher frequency range (>100 kHz) signifying strain mediated mechanical coupling between ferrite and dielectric phases which is calculated in terms of the coupling coefficient (γ).

Temperature and pressure dependences of the soft-mode frequency ((omega)) and the dielectric constant ((varepsilon)) are studied for the tetragonal-cubic transition (T_C = 395 K) in BaTiO₃. We find that variations of the frequency and the dielectric constant with the temperature (pressure) are related to each other linearly close to the phase transition in this ferroelectric material. Instead of the Curie-Weiss behaviour of the dielectric constant, the critical behaviour of both soft-mode frequency and the dielectric constant is expressed by the power-law formulae, and the critical exponents are determined using the observed data from the literature. Our predicted frequencies of the soft mode at various pressures and temperatures, can be examined by the experimental measurements close to the tetragonal-cubic transition in BaTiO₃.

Cu–Ni–W thin films were deposited by varying the current density from –5 to –60 mA cm^–2 using the galvanostatic chronopotentiogram method on indium tin oxide (ITO) coated glass substrates. X-ray diffraction analysis revealed that Cu–Ni–W thin films exhibited face-centered cubic structures with the presence of specific crystallographic planes, particularly (111), (200) and (220) at 2θ values of 43.4°, 50.7° and 74.7°, respectively. The additional peaks observed at other 2θ values correspond to the NiW and Ni₄W phases. The scanning electron microscopy micrographs of the films demonstrated a uniform structure characterized by a compact and dense morphology. The surface of the films displayed a metallic lustre attributed to the presence of Cu, Ni and W. The cross-sectional micrographs of the films indicated an average thickness of 1.1 to 1.2 µm. The energy dispersive X-ray spectroscopy analysis have shown that an increase in deposition current density leads to a rise in the relative concentration of Ni and W within the films, whereas the concentration of Cu decreased. The XPS survey spectrum also confirmed the presence of metallic Cu, Ni and W in the deposits. It was found that film deposited at higher current densities favours the growth of a smaller crystalline size of 17 nm and a higher degree of texture coefficient of 2.48. The maximum micro-strain of approximately 16% was calculated from the peak broadening of the X-ray diffractograms. The strong (111) texture and nano-crystallites as confirmed by XRD, resulted in an outstanding corrosion resistance of 16.22 kΩ-cm² for the film deposited at –60 mA cm^–2.

This study investigates the electronic, transport and optical properties of selenium-doped zinc telluride (ZnSe_xTe_1−x) ternary alloys in the hexagonal wurtzite (B4) phase at varying selenium concentrations using DFT-based FP-LAPW methods at (x = 0.0, 0.25, 0.50, 0.75, 1.0). Structural properties were calculated using the WC-GGA functional, while electronic, transport and optical properties were computed using the mBJ-GGA functional. All the specimen exhibits direct bandgaps with a Γ–Γ transition. The lattice constants (a and c) decrease nonlinearly with more selenium, while the bulk modulus (B) and bandgap (E_g) increase. The electronic transport properties were evaluated through the Seebeck coefficient, electrical conductivity, electronic thermal conductivity and electronic power factor. Additionally, the optical properties due to scattering were computed, and the results reveal the optically anisotropic nature of all the studied alloys, with birefringence clearly observed. The optical energy gap (E_opt) of each ternary alloy lies in the UV region, promising for UV optoelectronic device applications.

This study synthesised zeolite from bentonite clay, utilizing an ultrasound-assisted technique and response surface methodology (RSM) to optimize the process. Bentonite clay was dehydrated by calcining at 800°C for 1 h. Thereafter, dehydrated bentonite clay was subjected to alkali dissolution using ultrasonication and hydrothermal treatment. In the alkali dissolution stage, optimum conditions of 2.5 M of NaOH at 2 h of sonication were determined using the RSM tool, showcasing a SiO₂ and Al₂O₃ composition of 26.93 and 4.64%, respectively. After alkali dissolution, the obtained residues from the remaining dehydrated bentonite clay were characterized using X-ray fluorescence (XRF) to observe the remaining silica and alumina composition. In hydrothermal treatment, the synthesized zeolites were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD) and fourier-transform infrared spectroscopy (FTIR). The RSM analysis indicated optimum hydrothermal treatment conditions of 105°C for temperature treated at 1 h 30 min. Furthermore, the RSM plots for hydrothermal treatment showed that the crystallinity of the obtained zeolite samples increased with hydrothermal temperature and time. Moreover, the characterisation results showed that lower hydrothermal temperatures and crystallization times exhibited zeolite NaP phases with uniform spherical morphology, whilst higher temperatures and times exhibited hydroxy sodalite phases and large irregular particles. This methodology offers a promising approach for efficient and controlled zeolite synthesis from bentonite clay with the assistance of RSM.

This study investigates γ-ray shielding properties of Ni–Ti–Hf shape memory alloys under uniaxial tension, correlating their mechanical properties with linear attenuation coefficients (LAC). We evaluated LAC (cm^–1) values across various photon energies (E (MeV)), Ti:Hf ratio and APF, revealing an increase in LAC as (E, Ti:Hf, APF, LAC): (0.1, 2:3, 0.70, 32.5) to (0.1, 0:5, 0.74, 49.8) for samples subject to maximum deformation. The mechanical properties were also found to correlate very well with the γ-rays attenuation under optimal conditions. Notably, the plastic deformation of the alloys was found to enhance radiation shielding performance, with a significant reduction in γ-ray transmission (e.g., LAC = 1520 cm^–1) observed in samples with higher mass recovery (e.g., 120%) rates post-deformation. These findings underscore the importance of maintaining alloy density and optimizing mechanical properties for effective radiation shielding in practical applications.

In this study, a novel aligned hierarchical Zn(OH)₂/GaN heterostructure was fabricated at low temperature through a solution-based approach, offering a promising strategy for anisotropic ultraviolet (UV) photodetection. The structure consists of vertically aligned two-dimensional Zn(OH)₂ nanosheets grown epitaxially on a lateral epitaxial overgrowth uncoalesced GaN film. Photoresponse measurements reveal an excellent photoresponse performance with anisotropic photoresponse properties. This anisotropy stems from the directional charge transport pathways facilitated by the aligned Zn(OH)₂ nanosheet/uncoalesced GaN structure. These findings provide a new method to design high-performance UV detection sensors based on GaN grown using lateral epitaxy.

Lightweight and mechanically strong sandwich panels are extensively used in the aerospace, defence and energy sectors. In this context, the present study aims to develop high-strength lightweight multifunctional composites using epoxy and reticulated vitreous carbon (RVC) foam. For this, epoxy-infiltrated RVC foams were prepared by the scalable vacuum-assisted resin transfer moulding (VARTM) technique. The complex porous structure of RVC foam, owing to its local variations in the density as well as open-cell content, entails variations in the compressive strength of the composite, making it a function of density and porosity. To rationalize the statistical variations in composites, the Weibull distribution was used to predict compressive properties, measured on a large number of specimens. The Weibull analysis revealed a regression coefficient of 0.98 and a characteristic strength of ~75.1 MPa. The average compressive strength and modulus of the epoxy–RVC foam composite were found to be 68.52 ± 16.03 and 1303.7 ± 141.63 MPa, respectively. Moreover, the flexural strength and modulus of these composites were found to be 33.6 ± 6.6 and 4.73 ± 2.6 GPa, respectively. In addition, the composites showed electromagnetic interference shielding effectiveness of >20 dB with absorption domination in X-band frequency. On account of its lightweight, promising microwave absorption and mechanical properties, epoxy–RVC foam composites are potential candidates as multifunctional core materials in sandwich panels.

In this study, metal nitrates were used as precursors and citric acid as a chelating and combustion agent to synthesize lithium-substituted zinc ferrite Li_xZn_1−xFe₂O₄ (0.00 ≤ x ≤ 0.12) for gas sensing applications that aim to detect small traces of NH₃ molecules. The effects of Li-doping on the structural and morphological properties of Li_xZn_1−xFe₂O₄ nano-ferrite were investigated using X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). XRD findings indicated that the synthesized samples formed a pure phase with crystallite sizes ranging from ∼17–28 nm. The preparation process produced spherical particles with high porosity, as confirmed by FESEM images. The grain size of the samples was calculated using the Image J software. The gas response of ZnFe₂O₄ nano-ferrite with different Li doping at different operating temperatures and a constant NH₃ gas concentration was studied. Sensing measurements revealed that Li doping increases the ZnFe₂O₄-based sensor’s response to NH₃ gas. At 200°C, the 0.12 Li–ZnFe₂O₄ nano-ferrite showed the highest sensitivity. Li_xZn_1−xFe₂O₄ is a promising candidate to fabricate an ammonia sensor with high performance.