Journal of Electronic Materials最新文献

LiCoO₂ is widely used as cathode material for Li-ion batteries, owing to its easy synthesis and attractive volumetric energy density. However, the instability of the structure under high voltage limits the charge/discharge voltage below 4.2 V, thus delivering half of the theoretical capacity, which constrains the further expansion of applications. Elemental doping is often used as an effective strategy to improve material properties. Therefore, Sb-doped LiCoO₂ is systematically studied based on first principles calculations in this work. The substitution formation energy calculation shows that the incorporation of Sb into LiCoO₂ cathode is thermodynamically favored. The incorporation of Sb expands the unit cell and elongates the Li-O bond, which is conducive to the improvement of rate performance. Electronic structure analysis shows that Sb doping increases the electronic states near the Fermi energy level and enhances the electronic conductivity of the cathode. In addition, the findings show that Sb doping helps to enhance the discharge voltage and cycle stability of LiCoO₂ cathode, where LiCo_0.917Sb_0.083O₂ has better cycle stability. This study provides a theoretical basis for the design of high-performance LiCoO₂ cathodes.

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Two Cu-based metal-organic frameworks (MOFs), HKUST-1(RT) and HKUST-1(ST), were synthesized using room-temperature and solvothermal methods, respectively. Structural characterization revealed optical band gaps of 3.61 eV for HKUST-1(RT) and 3.58 eV for HKUST-1(ST). HKUST-1(RT) exhibited higher porosity and small, irregularly shaped layered sheets, whereas HKUST-1(ST) displayed reduced porosity and larger layered sheets. Zeta potential measurements at neutral pH indicated negatively charged surfaces (−5.64 mV for HKUST-1(RT) and −3.75 mV for HKUST-1(ST)), enhancing the electrostatic adsorption of positively charged methylene blue (MB) molecules. The adsorption kinetics disclosed that pseudo-second-order kinetic model explains the experimental data and has high correlation coefficients of 0.9831 for HKUST-1(RT) and 0.9816 for HKUST-1(ST) at a 0.50 g/L adsorbent dose. The outcome of the intraparticle diffusion model revealed an initial fast adsorption of the dye molecules followed by a slower diffusion inside the pores of HKUST-1. The impact of experimental factors viz dye concentration (0.02–0.14 g/L) and adsorbent dose (0.25–0.50 g/L) were systematically studied. By modeling the adsorption isotherms using Langmuir and Freundlich equations, it was found that the Langmuir model provided a superior fit for both materials. These findings highlight the potential of HKUST-1(RT) and HKUST-1(ST) for efficient dye adsorption applications.

Nanocrystalline Bi_1−xGd_xFe_1−xCr_xO₃ (x = 0.00, 0.04, 0.08, 0.12, 0.16) samples were fabricated via sol–gel autocombustion. x-Ray diffraction analysis (XRD) confirmed a single-phase rhombohedral structure. Crystallite size ranged from 30 nm to 25 nm, emphasizing their nanoscale characteristics. The lower bulk density compared with the x-ray density indicated the presence of pores. Lattice constants were computed with Cell software, indicating that substituting Bi³⁺ with the smaller Gd³⁺ ions resulted in modifications to the lattice structure. Fourier-transform infrared (FTIR) spectra revealed absorption bands between 400 cm⁻¹ and 600 cm⁻¹, with shifts observed as the Gd concentration increased, signifying doping effects on the structure. A decrease in the frequencies of both ν₁ and ν₂ bands was observed, attributed to the disruption of the Fe³⁺–O²⁻ bond and the rearrangement of cations due to Gd incorporation. Dielectric studies performed at room temperature within the 1–3 GHz range revealed a decrease in both real and imaginary parts of permittivity as frequency increased, consistent with the Maxwell–Wagner polarization model. At higher frequencies, the alternating-current (AC) conductivity increases substantially owing to the contribution of grains and enhanced polarization at neighboring sites. The sample with x = 0.16 exhibited low dielectric losses of 0.21 GHz at 3 GHz. The decrease in the quality factor is linked to a rise in loss caused by the formation of pores within the grains. Moreover, for x = 0.16, a reflection loss of −66.57 dB was measured at 0.98 GHz. These findings highlight the potential of these materials for cutting-edge uses, especially in multilayer chip inductors and high-frequency microwave systems.

Wireless sensor networks (WSNs) consist of numerous autonomous sensor nodes distributed across a physical environment to monitor various occurrences. A key challenge in WSNs is ensuring efficient data collection and energy replenishment of sensor nodes. While several strategies exist to integrate mobile data collection with node recharging, many face limitations in scalability, energy efficiency, or latency. This proposed approach that combines data collection and sensor node charging is based on coati optimization. Initially, sensor nodes are uniformly deployed across the sensing area, with equal transmission ranges and energy capacities. The region is divided into grids, and grid coordinates are selected within each grid using a weight function that considers both the remaining energy of sensors and their average distance from neighboring nodes. To prevent node energy depletion, two mobile chargers (MCs) are simultaneously dispatched along optimized routes derived through coati optimization. After each service round, the MCs return to the sink to transmit collected data and recharge. Experimental results demonstrate that the proposed method achieves a 31% reduction in packet delay, a 0.023% bit error rate, 6.2% energy consumption, and a 42% signal-to-noise ratio, highlighting its effectiveness in enhancing WSN performance. Thus, coati optimization proves to be a promising strategy for efficient data collection and sensor node charging.

There is a need to develop a skutterudite-based thermoelectric power generation module that can be used stably for long periods in high-temperature atmosphere, but the durability of p-type skutterudite compounds is generally lower than that of n-type skutterudite compounds in a high-temperature atmosphere. Thus, a thermoelectric generation module consisting of 14 pairs of p-type In_0.25Co₃FeSb₁₂ with an InSb layer formed on the surface and n-type In_0.25Co_3.88Ni_0.12Sb₁₂ has been fabricated using Ag sheets as electrodes and metal paste as bonding material. When the temperatures at the cold side and the hot side of the module were kept at 293 K and 773 K, respectively, a maximum power density of 2.46 kW m⁻² was obtained. During a long period of operation of 500 h in the air, with an increase in the elapsed time, the electric resistance of the module increased slightly, while the maximum electric power tended to decrease. The reduction in the maximum electric power of the module during continuous operation was estimated to be approximately 2%. On the other hand, for a module using p-type In_0.25Co₃FeSb₁₂ device material with no InSb layer formed on the surface, an 8% increase in the electrical resistance and a 12% decrease in the maximum electric power were observed after operation for 170 h in the air. This result indicates that the InSb layer formed on the surface of the p-type In_0.25Co₃FeSb₁₂ device material can significantly improve the durability of the module in the air at high temperature.

Heterojunction WS₂/p-Si thin film was synthesized using the chemical bath deposition (CBD) method. X-ray diffraction patterns show that the WS₂ thin film has high crystallinity with a hexagonal phase and crystallite size of ~221 nm. Field-emission scanning electron microscopy (FESEM) shows a petal-like morphology. The optical characteristics of the deposited WS₂ thin film were examined using ultraviolet–visible (UV–Vis) spectroscopy and photoluminescence (PL) spectroscopy, revealing an optical bandgap of approximately 2.33 eV in the visible spectrum. The PL emission spectrum shows multiple emission peaks between 400 nm and 675 nm. Current–voltage (I–V) characteristics were measured in the dark and at different light wavelengths, with the estimated ideality factor ranging from ~1.52 to ~1.67, which is very close to the ideal value for a diode. Current–time (I–t) measurement of the WS₂ thin film shows response and recovery time of ~0.01 s. The measurement at 5 V and forward biasing shows the lowest recovery and response time, which make it highly effective for detecting light in a broad range from the near-infrared to UV region.

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Secondary aluminum ash was modified with malic acid to prepare the adsorbent for a fluoride absorption. The effects of contact time, adsorbent dose, and pH on the defluorination effect of adsorbent were investigated. The structure and properties of the adsorbent were characterized by SEM, EDS, N₂ adsorption–desorption isotherm, XRD, FTIR, TEM, XPS, and removal rate. The results show that the surface roughness of the secondary aluminum ash modified by sintering and malic acid gradually increased. The BET specific surface area and pore volumes of secondary aluminum ash modified by sintering and malic acid were 42.691 m²/g and 0.128 cm³/g, respectively. The peak strength of F in the secondary aluminum ash was enhanced after adsorption, and the main phase in the ash was γ-Al₂O₃. The –OH peak of the modified secondary aluminum ash was enhanced and the –OH peak strength was weakened after adsorption of fluoride. The spacing between the interplanar distance of the adsorbent material was 0.24 nm. The fluoride adhered to the secondary aluminum ash surface by mainly substituting the hydroxyl group (–OH) on the surface of the adsorbent and forming an Al-F complex. When pH = 2, the maximum adsorption capacity was 92.8 mg/g. The adsorption process accorded to the pseudo-second-order kinetic model, the correlation coefficient, R² = 0.9995, indicating that the defluorination was chemisorption. The adsorption mechanism is mainly ion exchange and the formation of complexes. The liquidus temperature of the fluoride-containing Al₂O₃ industrial electrolyte system was 913 °C. The Al₂O₃ solubility in fluoride-containing Al₂O₃ electrolyte increased by 0.9 wt% compared to traditional aluminum industry electrolytes.

Ammonia (NH₃) is primarily produced through the traditional Haber–Bosch (H–B) technology which features high energy consumption and high pollution. As a sustainable alternative, electrocatalytic nitrogen reduction (eNRR) has attracted significant attention for its potential to replace the H–B process under ambient conditions. The key challenge lies in developing efficient catalysts to achieve high Faradaic efficiency (FE) for eNRR at normal temperature and pressure. Here, a metal-free composite catalyst composed of hexagonal boron nitride nanosheets (h-BNNs) and graphene oxide (GO) (h-BNNs/GO) was designed for ambient eNRR. A weak strain effect was induced between the layered structure of GO and h-BNNs, which contributed to an enhanced NH₃ yield rate of 25.0 μg h⁻¹ mg_cat.⁻¹) at −0.7 V versus reversible hydrogen electrode (RHE) in neutral media. Notably, the composite catalyst exhibited a remarkable 52.6% FE, a significant improvement over pure h-BNNs (4.7% FE). Furthermore, the morphology of the carbon support (e.g., GO vs. CNTs) was found to influence the strain effect, directly impacting the eNRR performance. This work provides valuable insights for strain-engineered catalyst design, advancing the development of sustainable nitrogen fixation technologies.

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Deep Potential (DP) technology integrates deep learning with quantum mechanical computations, enabling the efficient handling of complex data from density functional theory (DFT) while demonstrating excellent computational accuracy and data analysis capabilities. Rhodium (Rh), one of the rarest and most valuable platinum group metals, plays a crucial role due to its strategic importance in the automotive and electronics industries. However, the computational process for Rh is hindered by a lack of appropriate potential models, resulting in time-consuming and resource-intensive calculations that limit its research applications. To fill this gap, we developed a high-precision interatomic potential using the DP method, successfully applying it to classical molecular dynamics (MD) simulations, thereby offering a new computational tool. We systematically compared the predictions of the constructed DP potential function with results from DFT across various physical properties, including lattice parameters, stability, and defects, confirming that the constructed DP potential function exhibits excellent accuracy consistent with DFT in physical property predictions. Notably, in terms of thermal transport properties, the phonons dispersion and thermal conductivity results obtained from the developed DP model still remain in high consistency with those from the DFT method. Additionally, MD simulations based on the DP framework indicate that the crystal melts at a temperature of 2283 K, which is remarkably consistent with the experimentally measured melting point of 2237 K. With rising temperature, the transport of Rh atoms significantly enhances, with a self-diffusion coefficient of 7.54 × 10^-11 m²/s at the melting point, exhibiting diffusion behavior similar to that of typical face-centered cubic metals. This study serves as a foundational step in the application of deep learning to potential energy modeling of single-element Rh systems, ensuring the accuracy and reliability of the model. By extending this approach to multi-component systems in future work, it aims to provide theoretical support for the efficient and precise design of advanced materials.

In this work, the frequency-dependent conduction mechanism and dielectric relaxation processes in Bi₂Ca_2−xLa_xCoO_6, x = 0.00−0.15 (BCLCO), were investigated at temperatures between 100°C and 500°C. In this study, the novel BCLCO was successfully prepared by the coprecipitation process. We revealed the samples under study have a monoclinic structure by the investigation of x-ray diffraction (XRD) data. The XRD data was used to compute the crystallite size, lattice parameters, and unit cell volume. It is evident from all of the characterizations that the BCLCO was successfully prepared. Electrical and dielectric properties were examined with frequency at different temperatures. According to the analysis of electrical conductivity, the prepared samples exhibit semiconducting behavior. The dielectric constant is enhanced with temperature and decreases with frequency due to space charge polarization, which has been described by the Maxwell–Wagner relaxation model. In this investigation, the dielectric constant was examined up to a maximum value of 2.17 × 10⁶. In the studied samples, the Havriliak–Negami model was employed to calculate the spreading factor values. Jonscher’s universal power law was used to study the conduction mechanism of the synthesized samples. tan δ and dielectric constant studies confirmed the thermal hopping of charge transport in BCLCO. According to modulus spectroscopy, the examined samples indicated the existence of a temperature-dependent relaxation mechanism. The thermal conductivity (k = 0.540 W/m-K) was greatly reduced by La-doped bismuth cobaltite, which could make it appropriate for thermal barrier coating.

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