Journal of Electronic Materials最新文献

The [Ca₂₄Al₂₈O₆₄]⁴⁺:4e⁻ electronic compounds (C12A7:e⁻) with low work function and stable chemical properties have been employed in electron emission and optical devices. In this paper, C12A7:e⁻ was successfully prepared using CaO, Al₂O₃, and Al powders through spark plasma sintering (SPS) at 1250°C for 20 min. The grain size of the sample does not exceed 10 µm. The sample exhibits typical Raman peaks at 175 cm⁻¹, 329 cm⁻¹, 510 cm⁻¹, 780 cm⁻¹, and a clear ultraviolet absorption peak at 2.6 eV. The carrier concentration of the sample reaches 1.67 × 10²¹ cm⁻³. The emission current density of the sample at 4000 V and 1100°C is 1.34 A/cm², with a fluctuation of no more than 5%. The zero-field emission current density is 1.18 A/cm² at 1100°C. The lattice thermal conductivity of C12A7:e⁻ decreases with increasing temperature, reaching 12.59 W/(K m) at 1100°C. In addition, the band structure of C12A7:e⁻ includes valence band (VB), cage conduction band (CCB), and frame conduction band (FCB), and CCB extends to the Fermi level and has a bandgap of 0.82 eV with FCB. This makes C12A7:e⁻ exhibit a typical band conduction mechanism. The electron emission characteristics of C12A7:e⁻ are derived from the contributions of the s-orbital electrons of Ca atoms and the p-orbital and d-orbital electrons of Al atoms. This article simplifies the preparation steps of C12A7:e⁻ cathode materials, shortens the synthesis cycle, and provides a foundation for the research of C12A7:e⁻ cathode.

This work demonstrates the successful synthesis of pure α-Fe₂O₃, pure ZnO, and α-Fe₂O₃/ZnO nanocomposites with weight ratios of 1:1, 1:2, 1:3, and 1:4 by an efficient hydrothermal method for wastewater treatment. The structural, morphological, optical, and magnetic properties of the synthesized samples were characterized by x-ray diffraction (XRD), high-resolution transmission electron microscopy (HR-TEM), ultraviolet–visible (UV–Vis) spectroscopy, and vibrating-sample magnetometry (VSM), respectively. The XRD pattern confirmed the successful formation of the synthesized samples. Particle size in the range of 30–36 nm was calculated for the nanocomposite using HR-TEM. UV–Vis spectroscopy was used to calculate the optical bandgap of the synthesized nanocomposites, which varied from 1.96 eV (FZ11) to 2.27 eV (FZ14). This difference was explained by the introduction of ZnO, which is a wide-bandgap semiconductor. The value of magnetization decreased from 0.37 emu/g to 0.04 emu/g as the content of ZnO increased. The α-Fe₂O₃/ZnO nanocomposite with a weight ratio of 1:4 showed 85% photocatalytic degradation of methylene blue (MB) dye under UV light illumination with synchronized extraction for 105 min.

Thermal interface materials (TIMs), which are recently being used in high-power and new-generation materials, improve thermal stability at high temperatures because of the formation of intermetallic compounds. In this study, Cu-type Ga-based TIM solder has been selected to investigate the interface reaction of Ga-based thermal interface materials after curing, annealing, and reflow. During the curing process, liquid Ga diffuses through the X-alloy and reacts with Cu, resulting in the formation of the CuGa₂ phase. With the increase of annealing time, the area fraction of CuGa₂ and Cu₉Ga₄ decreases by 38% and increases by 44% because of the further diffusion of Cu into Ga, respectively. During reflow, the diffusion of Cu atoms into Ga leads to the formation of the solid solution of Cu and Ga. Meanwhile, the melted X-alloy reacts with Cu and forms Cu₆X₅.

This study presents an analysis of magnetoelectric nanoparticles (MENPs) through the development of equivalent circuits to predict the frequency-dependent magnetoelectric coefficient, with a focus on the widely utilized CoFe₂O₄@BaTiO₃ core–shell configuration. This approach involves –derivation of phenomenological expressions that capture the dynamic behavior of MENPs under varying magnetic and electric fields. By integrating piezoelectric and magnetostrictive constitutive equations, along with consideration of dynamic effects and bio-load conjugation, a magneto-elasto-electric effect equivalent circuit has been constructed. This circuit model not only facilitates the investigation of longitudinal data in cube-shaped MENPs but also offers insights into fundamental biological processes. The versatility of this model is shown through translation to other core–shell nanoparticles, composite structures, and multiferroic nanostructures. This analysis provides quantitative predictions of the magnetoelectric coefficients, enhancing general understanding of MENP characteristics across a broad frequency range. Furthermore, the study highlights the framework for future refinement to incorporate intrinsic composition-specific resonances, such as ferromagnetic and ferroelectric resonances, to further significantly improve the nanoparticles’ performance. Overall, this work lays the groundwork for future technology to intelligently and wirelessly control biological processes using MENPs, thus paving a way for innovative biomedical applications. This quantitative approach may facilitate further interdisciplinary research and contribute to advancement of magnetoelectric materials and their applications.

In this study, Mn_0.15Mg_0.15Cu_0.2Zn_0.5Fe_2−xTi_xO₄ (x = 0.0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6) nanoparticles were synthesized using the sol–gel auto-combustion method, and their structural, magnetic, and optical properties were investigated. Various characterization techniques were employed, including X-ray powder diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, and magnetization measurements. The Rietveld refinement of XRD data confirmed that the samples exhibited a cubic spinel structure with space group Fd (overline{3 })m. This conclusion was further supported by the results of FTIR and Raman spectroscopy. Interestingly, the particle size of the samples increased with an increase in the tetravalent Ti⁴⁺ substitution. In contrast, the crystallite size and lattice parameter decreased. The optical properties of the samples were studied, revealing a maximum energy gap value in sample x = 0.3. Furthermore, the saturation magnetization decreased from 41.47 emu/g in sample x = 0.0 to 7.36 emu/g in sample x = 0.6. Overall, this comprehensive investigation demonstrated the tunable properties of Mn_0.15Mg_0.15Cu_0.2Zn_0.5Fe_2−xTi_xO₄ nanoparticles and highlighted their potential for various applications, particularly in the fields of magnetism and optoelectronics.

Studies on nanocomposite films with an optimized composition of 0.6ZnO-0.4BaTiO₃/Al₂O₃ were carried out to understand the effect of swift heavy ion (SHI)-induced modifications on the ferroelectric properties inspired by interface mixing. XRD measurements showed the presence of ZnO and BaTiO₃ phases in pristine film which was modified by irradiation. Surface modifications induced by SHI irradiation, as studied using AFM, revealed the evolution of nanosized rod and hillock-like microstructure on the film surface with the increase in irradiation dose. The variations in film thickness and elemental compositions were studied using RBS spectrometry, and an intermixing zone ~ 25 nm was identified in the film irradiated by 5 × 10¹⁰ ions/cm² which increased with the ion fluence. Ferroelectric (P-E) loops showed a significant change in the hysteresis characteristics which was understood on the basis of modifications in the surface morphology and the interface between the wurtzite-structured ZnO and the perovskite-structured BaTiO₃ responsible for the space charge region.

Defects and defective technology are considered to be an efficient method for improving electromagnetic wave (EMW) absorption performance. In this study, W-type barium hexaferrite BaCo₂Fe₁₆O₂₇ (BCFO) composites with Sm doping were synthesized by a simple ball milling and subsequent annealing process. The phase structure characteristics, magnetic properties, and microwave absorption performance of the BCFO composites were systematically investigated. Specifically, Sm-doped and annealed BCFO composites demonstrated outstanding microwave absorption characteristics because of the efficient interaction between ideal impedance matching and large dielectric loss, specifically, a minimum reflection loss (RL) value of −28.57 dB at 8.5 GHz with 3 mm thickness. Moreover, a broad effective absorption bandwidth reaches 11 GHz, covering the range of 7–18 GHz. It is believed that defects and vacancies induced by Sm doping or annealing in the Ar atmosphere may be an effective means for enhancing microwave absorption, and related mechanisms are discussed in detail.

The application of CdZnTe(CZT) crystals in infrared focal plane detectors and x-ray imaging detectors is hindered by the low infrared transmittance (IRT) and the presence of Cd/Te inclusions/precipitation. Over the preceding decades, strategies involving Cd vapor control during the growth process and substrate post-annealing have been posited to address these challenges. Presently, the prioritized approach is the utilization of substrate post-annealing, owing to the limited precision in comprehending the Cd-Te equilibrium and the intricacies associated with Cd vapor control technology. This study delves into the effect of the removed surface layer depth of a CZT and the selection of the (111) A-face or (111) B-face on IRT during Cd atmosphere annealing. It is recommended that a minimum of 60 μm of the surface layer be eliminated using chemical mechanical polishing technology before annealing. Experimental findings further reveal that Cd atom diffusion from the (111) A-face results in an IRT enhancement of up to 60%, in stark contrast to the slight improvement observed with the (111) B-face after annealing. The mechanism of Cd atom diffusions affecting the IRT in the annealing process is discussed.

Graphene-like materials are currently showing great potential in different fields, especially in energy storage. We synthesized N-GLC/MOF-74 composites by combining nitrogen-doped graphene-like carbon (N-GLC) with MOF-74. Three porous N-GLC/metal oxide complexes (A-1, A-2, and A-3) were successfully synthesized by calcining the synthesized composites at different temperatures (300°C, 400°C, and 500°C) under air atmosphere. The conversion of the MOF into metal oxides under high-temperature conditions and the oxidation of N-GLC into porous structures was revealed by characterization. The coulombic efficiency of A-1 reached 97.7% after 3500 long cycles at 5 A g⁻¹, indicating an improvement in the stability of the material. The results of this work support the potential use of graphene-like derivatives in energy storage applications.

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Herein, stacked layers of Nb₂O₅ structured with platinum nanosheets were fabricated to handle multifunctional electro-optic operations. The stacked layers of Nb₂O₅/Pt/Nb₂O₅ (NPN) were prepared by the ion coating technique and exhibited an amorphous structure. A remarkable increase in light absorption by more than 480% was achieved via the insertion of Pt nanosheets between layers of Nb₂O₅. Pt nanosheets with thicknesses of 50 nm and 100 nm successfully increased the electrical conductivity of the NPN layers by five and eight orders of magnitude, respectively, without losing transparency. This feature makes the NPN stacks suitable for transparent conducting oxide applications. The insertion of Pt nanosheets between layers of Nb₂O₅ also converted the conductivity from p- to (n)-type. In addition, NPN stacked layers exhibited highly enhanced dielectric properties, demonstrating an increase in the dielectric constant by 190%, making the NPN stacked layers suitable for use in the design of high-κ gate dielectric devices. Moreover, when treated as optical filters, Drude–Lorentz fittings of the dielectric spectra showed that Pt nanosheets increased the free carrier density and the plasmon frequency. The terahertz cutoff frequency of the NPN devices steadily increased with increasing Pt nanosheet thickness. The terahertz cutoff frequency for NPN optical filters comprising a 100-nm-thick layer of Pt displayed values of 7.5 THz and 5.0 THz in the infrared and visible light ranges. The NPN stacks have potential for use in terahertz applications.

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