Journal of Materials Science: Materials in Electronics最新文献

A novel Barium (II) Bis 15-Crown-5 ether Manganese (II) Thiocyanate single crystal were grown at ambient temperature, synthesized via the slow evaporation method. The single crystal X-ray diffraction confirms that the grown crystal system is tetragonal with a centrosymmetric space group I41/a. additionally, the cell parameters a = 28.13 Å, b = 28.13 Å, c = 9.73 Å and V = 7697(4) ų were observed and well-matched with both powder and single crystal X-ray diffraction. The UV–Vis optical transmission spectrum shows that the grown crystal cut-off wavelength of 281 nm, using Tauc's plot a band gap value of 3.36 eV. The CN stretching vibrations of NH₄(SCN) functional group were found to be in FTIR and micro-Raman spectroscopy studies. The reverse growth rates and rectangular shape layered etch pattern of the grown crystal were investigated using etching studies. The thermogravimetric curve showed the decomposition temperature was found at 100 °C, differential thermal analysis curve revealed two endothermic peaks at 150–200 °C and 250–300 °C, respectively. The mechanical stability of grown crystal confirmed as hard material (n = 1.4) was tested by Vickers micro hardness studies. The Z-scan measurement operate at 532 nm Q-switched Nd: YAG laser, revealing the reverse saturable absorption, the calculated nonlinear absorption coefficient (β) is 0.68 × 10⁻¹⁰ m/W and optical limiting threshold value is 2.42 × 10¹² W/m². The above mentioned results suggest that the grown crystal has favorable optical transmittance, moderate thermal and mechanical stability, excellent optical limiting property, therefore the grown crystal is suitable for non-linear and optical limiting applications.

The high temperatures and long times required to synthesize CeNbO₄ (CN) and Mn₃O₄ (M) negative temperature coefficient (NTC) ceramics are unfavorable for controlling their grain size and electric properties. Herein, CN and 0.5CeNbO₄–0.5Mn₃O₄ (CN-M) ceramics were rapidly prepared (15–60 s) via the reactive flash sintering (RFS) of CeO₂, Nb₂O₅, and Mn₃O₄ powders at 300 °C using a 333 V cm⁻¹ electric field and current densities of 50–500 mA·mm⁻². A single-phase CN structure was formed under a current density of 100 mA·mm⁻² and a flash time of 60 s. However, for CN-M, the complete reaction of Nb₂O₅ and CeO₂ required a 400 mA·mm⁻² current density and a flash time greater than 60 s. As the current density and RFS time increased, the density and grain size of the ceramics also increased, influencing their resistivity. The predominant RFS mechanism of these ceramics was identified as the electric field-enhanced diffusion of oxygen interstitials and oxygen vacancies.

This study focuses on the calcination temperature, between 600 and 1050 °C, used to prepare La_0.67Sr_0.33MnO₃ (LSMO) nanoparticles via a non-aqueous sol–gel method, with respect to their structure, magnetism, and magnetotransport properties. The X-ray diffraction and Rietveld refinement indicate phase-pure nanoparticles in a rhombohedral (R-3c) structure. Moreover, they evidence the rise of the average size of crystallites from 31.9 to 111.4 nm with the lowest microstrain at about 900 °C. Magnetic measurements demonstrate that reduced surface disorder at increased temperatures enhances the saturation magnetization (Mₛ) sixfold, increasing from 6.86 to 38.14 emu/g with the calcination temperature increase. However, the data indicate the transition in magnetic behavior: coercivity and remanence increase up to a maximum at 900 °C and then decline, marking the transition between single-domain and multi-domain behavior. Room-temperature magnetoresistance measurements identify an inverse dependence of the particle size on the magnitude of low-field magnetoresistance (LFMR)—larger particles have lower LFMR. The sample calcined at 600 °C, where intergranular spin-polarized tunneling occurs across many grain boundaries, has a very large LFMR of more than 95%. In contrast, for the 1050 °C sample, larger grain size allows better magnetic coherence and fewer boundary regions and, hence, it has a much weaker MR of about 40%. The findings show that calcination temperature is the main tuning knob for LSMO nanoparticles; it allows a predetermined balance between hard magnetic characteristics for magnetic components with high sensitivity in magnetoresistive devices for sensor applications.

This work introduces an innovative synthesis of α-Fe₂O₃ (Fe), Co₃O₄ (Co), and NiO (Ni) nanoparticles based in the following metal–organic frameworks (MOFs): Fe-MOF, Co-MOF, and Ni-MOF, respectively. These nanoparticles were combined with carbonyl iron (CI) via solid-state synthesis for use as microwave-absorbing materials (MAMs) in the K-band particularly within the 24–26 GHz frequency range. The synthesized materials were characterized structurally by X-ray diffraction (XRD), morphologically by scan electronic microscopy (SEM), and elemental qualitatively the composition by electron dispersive spectroscopy (EDS). The electromagnetic (EM) characterization was performed using a vector network analyzer (VNA) with Keysight^® software to extract the complex relative electric permittivity, and complex magnetic permeability via the Nicholson Ross Weir (NRW) method based on measured S-parameters. Additionally, reflectivity-based EM simulations were conducted to assess impedance matching and determine optimal absorb thicknesses. The results indicate that each synthetized material exhibits distinct electromagnetic behavior, and the proper combination of composition and thickness can yield promising MAM composite. Notably, the combination between nano Fe/ CI achieved a reflection loss lower than −15 dB at a thickness of 1.20 mm, while Co/CI and Ni/CI exhibited superior performance, with minimum reflection loss of −23,45 dB and −26,21 dB respectively. This work provides a novel approach to developing advanced composites for K-band microwave absorption, addressing the growing demand for effective EM pollution.

Reinforced Bi-2223 superconducting tapes are promising candidates for high-field and cryogenic applications, yet their overall performance is often limited by interfacial degradation under the combined action of electrical, magnetic, thermal and mechanical loads. In this work, the interfacial mechanical properties of reinforced Bi-2223 tapes were improved by introducing controlled sub-micron roughness on stainless-steel laminations prior to soldering. Three typical roughness levels were prepared, and their effects on shear and peel resistance, solder wettability, interfacial electrical resistance, and defect evolution were examined. Increasing the roughness led to a clear enhancement in bonding quality: at 77 K, the peel failure load increased by 144%, and the shear failure load increased by 12.5%. The improved performance is attributed to better solder wetting, reduced interfacial voids, and a larger effective bonding area, together with roughness-induced contact geometry that enhances load transfer capability. The structure–property relationships revealed in this study provide guidance for designing reinforced Bi-2223 conductors with improved mechanical reliability, and offer a practical approach for strengthening the interfaces of multilayer superconducting systems.

In this study, the microstructural, electrical, and electromagnetic properties of MgB₂ bulk superconductors modified with the organic additive of phenyl(3-phenyloxirane-2-yl)methane (C₁₅H₁₂O₂) were investigated. Pure and bulk MgB₂ samples doped with 0–20 wt% C₁₅H₁₂O₂ were produced by in situ Spark Plasma Sintering (SPS) at 850 °C, 50 MPa pressure, and 10 min. X-ray diffraction analyses showed that the hexagonal MgB₂ phase was predominantly preserved in all samples, with limited MgO formation observed at increasing addition rates. SEM analyses revealed that organic additive created controlled porosity and microstructural heterogeneity. Electrical measurements showed a limited decrease in the superconducting transition temperature and an increase in the normal-state resistivity in the doped samples. Magnetic characterization results revealed that the sample containing 15 wt% C₁₅H₁₂O₂ exhibited the highest critical current density and optimized pinning force at 20 K. Levitation force measurements performed under ZFC and FC conditions have shown a strong correlation between microstructure-derived pinning architecture and electromagnetic response. The results reveal that C₁₅H₁₂O₂ addition offers a suitable approach for effectively tuning the pinning and levitation properties of SPS-generated MgB₂ bulk superconductors.

Improvement of the growth mechanism of nanostructured CdS thin films prepared by the chemical bath deposition (CBD) route has drawn attention to obtain high-quality films that can be used for advanced technical and industrial applications. In this study, the influence of a CW green diode laser illumination during chemical bath deposition on the structural and optical properties of cadmium sulfide (CdS) thin films deposited on porous silicon was examined. The X-ray diffraction studies reveal that using a laser during the deposition of CdS film leads to the formation of nanocrystalline CdS with a cubic structure. The stoichiometry of the CdS film is improved with laser assistance. The value of the optical energy gap of the CdS film, as determined from UV–Vis absorption, increases from 2.54 to 2.66 eV when laser illumination is applied. The scanning electron microscope result shows that the agglomeration of the CdS particles decreases when laser illumination is applied, and the CdS particles are well embedded inside the pores of the porous silicon (PSi). The figures of merit of the CdS-embedded PSi/c-Si photodetectors are significantly enhanced after using laser illumination. The responsivity of the photodetector increases from 5 to 8 A/W at 600 nm when the laser beam illumination applied during deposition is adjusted. The rise/fall time and ON/OFF current ratio are found to be improved for the photodetector prepared with laser illumination.

We synthesized Er-activated CaF₂ translucent ceramics with several doping concentrations (0.1, 1.0, 10, and 20%) to evaluate their near-infrared (NIR) scintillation performance. In the NIR scintillation spectra, the samples exhibited a main emission peak at 1540 nm. Under visible lights and X-rays excitation, the obtained decay time constants were comparable to 4f–4f transitions of Er³⁺. The photoluminescence quantum yields in the 940–1640 nm wavelength range of 0.1, 1.0, 10, and 20% Er-activated samples were 20, 37, 50, and 27%, respectively. In the dose rate response measurement, the 10% Er-activated sample showed good linearity and lower detection limit of 0.61 mGy/h, suggesting its potential applicability for high dose field radiation monitoring.

In this study, a ZnTiO₃/Bi₂WO₆ nanocomposite photocatalyst was synthesized via a hydrothermal method and evaluated for enhanced photocatalytic performance. The as-prepared ZnTiO₃, Bi₂WO₆, and ZnTiO₃/Bi₂WO₆ samples were systematically characterized using X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM) with energy-dispersive X-ray spectroscopy (EDS), high-resolution transmission electron microscopy (HRTEM), Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, and UV-visible diffuse reflectance spectroscopy (UV-vis DRS). SEM analysis showed that the ZnTiO₃/Bi₂WO₆ nanocomposite is composed of quasi-spherical nanoparticles with an average size of ranging from 50.76 nm to 80.76 nm. The photocatalytic activity was assessed by the degradation of two hazardous organic dyes, Acid Green and Rose Bengal, under UV irradiation, achieving degradation efficiencies of 83.65% and 87.19%, respectively, within 60 min. The improved photocatalytic performance is attributed to efficient separation of photogenerated charge carriers and an increased number of active sites on the catalyst surface. Kinetic analysis indicated that the degradation of both dyes followed pseudo-first-order kinetics, and the nanocomposite exhibited excellent stability and reusability over three consecutive cycles, highlighting its potential for wastewater treatment applications.

The low-frequency electromagnetic radiation (LF-EMR) generated by high-power electric drive systems in new energy vehicles poses potential risks to human bioelectrical functions and vehicle electromagnetic compatibility. To address the lack of flexibility, lightweight and high-permeability shielding materials effective in the 1 Hz–10 kHz magnetic field range, this work constructs uniform Ni–Fe alloy coatings on conductive fiber fabrics via an optimized electrodeposition strategy. A systematic L25 (5³) orthogonal design reveals current density as the dominant factor governing coating compactness, Ni/Fe co-deposition behavior, and magnetic shielding performance, followed by temperature and pH. Under the optimal conditions (30 °C, pH 3.5, 3 A·dm⁻²), the Ni–Fe coating exhibits a dense microstructure, strong interfacial adhesion, and uniform elemental distribution, achieving an average shielding effectiveness (SE) of ~ 8 dB at 10 kHz with a thickness of 28.3 um—corresponding to ~ 70% attenuation of magnetic field intensity. Thickness-dependent analysis confirms that magnetic flux shunting arising from the high permeability of the Ni–Fe alloy dominates the shielding mechanism in the low-frequency regime, whereas eddy-current losses are minimal. Environmental stability tests demonstrate that the coatings maintain structural integrity and SE after high-temperature exposure, bending cycles, and water immersion. Frequency-dependent permeability derived from LCR measurements was incorporated into CST simulations, which showed excellent agreement with the experimental data and predicted broadband shielding capabilities of 33–91 dB in 10 kHz–30 MHz range. This study provides a practical, scalable, and mechanically flexible high-permeability coating system for low-frequency magnetic shielding in new energy vehicle applications.