Journal of Materials Science: Materials in Electronics最新文献

Crystallographic and magnetic structures of quadruple perovskite series, CaCu_3-xFe_2xTi_4-xO₁₂ (x = 0.0, 0.1, 0.3, 0.5, and 0.7), have been meticulously examined by powder X-ray diffractometry (PXRD) and neutron diffraction at ~ 300 K. The Rietveld refinement of PXRD profiles verified monophasic formation for all the compositions. Contrarily, analysis of neutron diffraction profiles revealed a single-phase nature for x = 0.0 and 0.1 compositions while for x = 0.3, 0.5, and 0.7 compositions, formation of a secondary Magneli phase, Ti₆O₁₁. Various structural parameters in conjunction with the distribution of cations have been resolute and discussed in depth. The magnetic spin structure established an anti-ferromagnetic (x = 0.3) to ferromagnetic (x = 0.5 and 0.7) phase transition. The disparity between the experimental and calculated magnetic moment is an inkling of a spin structure to be non-collinear for x = 0.3–0.7 compositions.

In this study, the (Ba, Ca)(Ti, Zr)O₃-based dielectric ceramics were prepared by the two-step sintering method. The effects of the first step sintering temperature (T1) on microscopic morphology and dielectric properties were investigated in detail. The two-step sintering method could effectively reduce the grain size and form a uniformly distributed microstructure. As a result, the temperature coefficient of capacitance (TCC) and the breakdown strength (BDS) were improved obviously, compared with the traditional one-step sintering. The finite element simulation of ceramics obtained by COMSOL was used further to reveal the functions of the different sintering conditions. When the optimum T1 was chosen, the average grain size decreased to 0.53 µm, with a simulated breakdown time of 0.78 s, the TCC was − 45.8% to 1.8% during the temperature range of − 30 to 85 °C and the BDS reached 165 ± 0.5 kV/cm, accompanied by a high dielectric constant (ε_r) of 6841 ± 103 and a low dielectric loss (tanδ) (0.51% ± 0.03%).

Among the current battery technologies, lithium-ion batteries (LIBs) are essential for shaping future energy sites in stationary storage. However, their capacity, cyclic stability, and high cost are still challenging in research and development. To overcome these drawbacks, nickel-rich ternary cathode materials, with their outstanding capacity, have become the linchpin materials. It represents a prominent class of cathode materials for LIBs due to their high energy density and capacity. A powder material exhibiting single-crystalline LiNi_0.88Mn_0.02Co_0.10O₂ (NMC-88) and LiNi_0.83Mn_0.06Co_0.11O₂ (NMC-83) cathodes was synthesized through the co-precipitation technique and systematically analyzed. Among these NMCs, the electrochemical evaluation of the NMC-88 revealed a high initial discharge capacity of 216 mAh/g and 190.7 mAh/g at 0.1 C and 0.5 C and achieved 70.6% retention after 90 cycles at 1 C, while the NMC-83 attained only 44.62%. The results suggest that the high nickel-rich NMC-88 cathode has good discharge capacity, rate capability, and cyclic performance, with better interface and stability than NMC-83.

Ca_0.94Ce_0.06Bi₄Ti_4-x(W_1/3Cr_2/3)_xO₁₅ (CCBT-WC_x, x = 0.00–0.10) ceramics were prepared by a solid-state sintering method, and the effect of W/Cr co-doping on the structure and electrical properties of the ceramics was systematically investigated. An enhanced piezoelectric constant d₃₃ (22.1 pC/N) was achieved at the optimized composition with x = 0.04, which increased by 35% as compared to that of pure CCBT ceramics due to more effective distortion of the titanium-oxygen octahedron induced by W/Cr co-doping. Moreover, after annealing at 500 °C, the d₃₃ (21.0 pC/N) of CCBT-WC_0.04 ceramics still remained 95% of its initial value, exhibiting excellent annealing thermal stability. In addition to a high Curie temperature (T_C = 768 °C), this ceramic should be very promising for high-temperature sensor applications.

In this work, NiCoO₂, consisting of nanostructured microspheres, was successfully synthesized via a simple solvothermal method for photocatalytic dye degradation. The synthesized photocatalyst was characterized using X-ray Diffraction (XRD), N₂ adsorption–desorption Brunauer–Emmett–Teller (BET), Scanning Electron Microscopy (SEM), energy dispersive X-ray emission (EDX), High-Resolution transmission electron microscopy (HR-TEM), X-ray Photoelectron Spectroscopy (XPS), and UV–Vis absorption spectroscopy techniques. The as-prepared NiCoO₂ exhibited a high specific surface area of 85.046 m² g⁻¹, as revealed in the BET studies. SEM images show that NiCoO₂ possesses nanostructures arranged in three dimensions to form microspheres, allowing easy access to the available high specific surface area for catalytic reactions. The XRD plots indicate a polycrystalline structure of NiCoO₂ with an estimated crystallite size of 13 nm. The optical band gap energy of NiCoO₂ was evaluated to be 2.69 eV, thus enabling it to absorb a large part of the visible light spectrum. High specific area and visible light absorption yield a high photocatalytic efficiency for dye degradation. It exhibited an efficiency of 98.12% within 60 min at a degradation rate of 0.06974 min⁻¹ for the decolorization of Rhodamine B. Thus, the study proposes an inexpensive photocatalyst NiCoO₂, consisting of nanostructured microspheres, for commercial dye treatment technology application.

Hydrothermally synthesized manganese dioxide (MnO₂) has attracted significant attention in supercapacitor applications due to its exceptional electrochemical properties. This research systematically explores the influence of hydrothermal temperatures of 105 °C (M1), 120 °C (M2), and 150 °C (M3) on the structural and electrochemical characteristics of MnO₂-based supercapacitors. From field effect scanning electron microscopy (FESEM) images, the average diameter of MnO₂ nanorods is 139 ± 3 nm, 140 ± 5 nm, and 156 ± 3 nm for M1, M2, and M3. The crystalline quality of MnO₂ increases by increasing the hydrothermal temperature (M3 sample). Shifting the Raman peak from 637 to 654 cm⁻¹ is observed due to the enhancement in crystallinity and nanorod size in the M3 sample. Higher surface area for smaller nanorods (M1) is also confirmed by the BET (Brunauer–Emmett–Teller) technique. At the scan rate of 10 mV/s, the specific capacitance obtained is 142 (M1), 135 (M2), and 131 (M3) F/g. By elucidating the intricate relationship between hydrothermal temperature and the resultant MnO₂ properties, this study provides valuable insights for optimizing the synthesis conditions to enhance the performance of MnO₂-based supercapacitors.

In this study, we present a novel approach to improve the performance of perovskite solar cells (PSCs) by exploring the synergistic effects of ultraviolet (UV) light and magnetic field (MF) exposure on the properties of ZnO thin films. These films serve as the electron transport layer (ETL) in PSCs. The ZnO thin were synthesized via a dip coating method. During the deposition process, the films were subjected to UV light (ZnO:UV), magnetic field (ZnO:MF), and a combination of UV and MF (ZnO:(UV + MF)) treatments. Our findings demonstrate that the ZnO:(UV + MF) film has an average transparency of 92% in the visible region, a high degree of crystallinity, and a broadened optical bandgap (3.69 eV). The current density–voltage characteristics of the four fabricated devices, using the untreated and treated ZnO thin films as ETLs, revealed an efficiency of approximately 10.80% when using ZnO:(UV + MF) as the ETL, surpassing the efficiency of 7.31% observed for the device with untreated ZnO ETL.

Metal oxide-based nanocomposites has been regarded as a useful tool for sensors technology to detect various hazardous gases at low concentrations. In this work, the CeO₂–ZnO composite was successfully synthesized using a simple chemical combustion method. The synthesized samples were characterized by employing different characterization techniques. The results demonstrated that the cubic fluorite phase of CeO₂ and the hexagonal wurtzite phase of ZnO have been obtained while the CeO₂–ZnO composite showed a mixed phase of CeO₂ and ZnO. The morphology of the CeO₂–ZnO products has a nanoporous structure. The well-defined structure of the CeO₂–ZnO nanocomposite was confirmed by the HR-TEM. Furthermore, gas sensing study showed that CeO₂–ZnO nanocomposite exhibited enhanced sensing properties toward ethanol at an operating temperature of 275 ℃. The gas sensitivity value was 61.75% toward 24 ppm ethanol. This could be attributed to the formation of the n–n heterojunction between CeO₂ and ZnO which enhances conductivity value to give more sensitivity.

An organic dibenzoylmethane single crystal was grown by slow evaporation method. Single crystal X-ray diffraction studies reveal that dibenzoylmethane crystal has an orthorhombic crystal structure and its unit cell parameters are a = 10.875 (± 0.004) Å, b = 8.769 (± 0.003) Å, c = 24.460 (± 0.009) Å, α = β = γ = 90° and volume = 2335 ų. Density functional theory (DFT) was used to calculate the optimized geometry, vibrational frequencies and electronic properties of the title compound. The fundamental vibrational analysis of the molecule obtained in FTIR spectra are compared with the theoretical results computed by DFT. The results obtained from UV–Vis–NIR spectroscopic transmittance spectra are in good agreement with theoretically obtained values using DFT method. The lower cut off wavelength and large band gap value of 4.48 eV of the crystal ensures its applications for optoelectronic devices. DFT was also used to report HOMO–LUMO bandgap energy, stability of the molecule by investigating NBO analysis, electrophilic and nucleophilic regions were identified using MEP map, topological research ELF and LOL to find bonding zone and weakest interactions in dibenzoylmethane. The atomic charge values of dibenzoylmethane were computed in Mulliken’s population analysis. The thermal stability of the crystal was studied using TG/DTA analysis. The material shows major weight losses of around 90% in the temperature between 79 °C and 270 °C. The fluorescence spectrum indicates that the crystal has emission at 401 nm and 602 nm wavelengths in visible region. The third order nonlinear susceptibility (χ³) = 3.65 × 10^–5 esu, nonlinear refractive index (n₂) = 6.42 × 10^–8 cm²/W and nonlinear absorption coefficient (β) = 7.2 × 10^–4 cm/W of the grown crystal were determined using Z-scan technique. According to these results the dibenzoylmethane crystal could be suitable for optoelectronic and photonic applications.

In underground command posts, the technology and equipment for welding large steel plates significantly influence the effectiveness of electromagnetic shielding in the overall construction. Herein, we introduce an electromagnetic shielding sealant designed to replace traditional full-welding techniques for joining steel plates, in which two-component polyurethane, nickel–iron alloy powder, and silane coupling agents were used as the foundational material, the filling compound, and the modifiers, respectively. Specifically, we examined the electrical resistivity, electromagnetic shielding efficiency, shear strength characteristics of the samples with nickel–iron alloy powder and polyurethane modified by various silane coupling agents under diverse conditions, including 3-aminopropyl triethoxy silane (KH550), 3-glycidyloxypropyl trimethoxy silane (KH560), 3-trimethoxysilyl propyl methacrylate (KH570), 3-mercaptopropyl triethoxy silane (KH580), 3-mercaptopropyl trimethoxy silane (KH590), and isocyanatopropyl triethoxy silane (IPTS). The results indicate that the optimal performance of the electromagnetic sealant is achieved when the nickel–iron alloy powder is modified with KH550, together with the addition of 0.5 wt% of KH560 into the polyurethane. A 1 mm thick sample exhibits low resistivity of 1.24*10^–4 Ω•m, high shear strength of 141 MPa, and good break elongation of 9.36% with electromagnetic shielding ranging from 57.9 dB to 102.7 dB in the frequency range of 30–1.5 GHz. As a result, a sample steel plate with a specific design exhibits a shielding effectiveness exceeding 60 dB across different frequency bands, fulfilling the criteria for practical engineering applications.