Journal of Materials Science: Materials in Electronics最新文献

Dielectric modulation of triboelectric materials has proven to be a viable approach for enhancing triboelectric nanogenerator (TENG) performance. Nevertheless, the construction of high dielectric composites with optimal interfacial compatibility and exceptional performance is a matter of immediate concern. Graphene oxide (rGO) was modified with pentafluorobenzoic acid (PFBA) to synthesize PFBA@rGO/PVDF-HFP composite films via the casting method. A mass fraction of 5 wt% PFBA@rGO results in a dielectric constant of 211 at a frequency of 40 Hz, which is 15 times greater than that of the pure PVDF-HFP film. Furthermore, the dielectric loss remains low at 0.7. The modification created a stable molecular interface between PVDF-HFP and rGO, improving the compatibility between the rGO filler and PVDF-HFP matrix. This interfacial polarization significantly boosted the composites’ dielectric constant, enabling PFBA@rGO in PVDF-HFP to react flexibly to external electric fields. The TENG with 5 wt% PFBA@rGO/PVDF-HFP achieves a maximum open-circuit voltage of 70 V, which is double that observed for pure PVDF-HFP. This enhancement results from the material’s high dielectric properties, which increase surface charge density. The TENG can light 69 LED bulbs and charge a 3.3 μF capacitor to 5 V in less than a minute. This study provides new insights into the unique potential of the dielectric-modulated output enhancement strategy for TENG in energy harvesting.

With the quick development of up-to-date social informatization, a harm of ubiquitous microwave absorption (MA) has become a significant issue to environment, communication industry, and human health. It is still a challenge to design high-performance absorbing materials to eliminate the harm of MA. In this work, the reduced oxide graphene (rGO) sheets decorated by aluminum nitride (AlN) and spherical-like structures of Fe₃O₄ nanoparticles were successfully fabricated via a one-pot solvothermal method. The rGO/Fe₃O₄/AlN hybrid composites as microwave absorbers exhibited superior MA performance by tuning the content ratio of Fe₃O₄ to AlN and the mass ratio of rGO/Fe₃O₄/AlN to paraffin was 3:7. Significantly, the minimum reflection loss (RL_min) value of rGO/Fe₃O₄/AlN-paraffin was − 59.39 dB at 14.24 GHz with a thickness of only 1.8 mm and the effective absorption bandwidth was 5.68 GHz (12.32–18 GHz) when the content ratio of Fe₃O₄ to AlN was 1:1.5. The introduction of proper content of AlN could enable excellent MA performance of hybrid composites due to the enhancement of the impedance matching and synergistic effect. Therefore, our present work may build up a new strategy for developing prospect MA materials with practical applications by facile preparation routes and low production cost control.

This study aimed to synthesize graphite-like activated carbon with different morphologies using the solvothermal method and to evaluate the effects of different acidifying agents on the structure, morphology, porosity, CO gas sensitivity, and optical properties. Graphite-like activated carbon was synthesized using the solvothermal method in an autoclave at 160 °C with four acidic agents: hydrochloric acid (HCl), phosphoric acid (H₃PO₄), sulfuric acid (H₂SO₄) and nitric acid (HNO₃). The activated carbon was produced using carbon black powder obtained from the carbonization process and the combustion of almond skin waste at 600 °C. The properties of the synthesized activated carbon were analyzed by XRD, FESEM, BET, UV–Vis spectrophotometry, and FTIR spectroscopy. The XRD analysis revealed that the AC-HNO₃ sample had the most graphite-like structure, with a d002 value of 3.67 Å and an Lc value of 10.02 Å. The 002 peak appeared near 2θ = 23°, and the 10L peak was observed as a broad peak near 2θ = 43°. The FESEM images showed that the carbon black sample had no pores, while the AC-HNO₃ sample had the highest porosity and the most uniform pore size, with pore sizes around 950 nm. The BET analysis also confirmed the largest specific surface area of the AC-HNO₃ sample with a surface area (({S}_{BET})) = 340 m²/g, which correlates with the superior light absorption capabilities compared to 67 m²/g for carbon black. The absorption spectrum demonstrated enhanced light absorption for all synthesized activated carbons compared to carbon black, with the AC-HNO₃ sample exhibiting the highest optical absorption coefficient (α) in the order of 10⁶. Optical band gap calculations showed a reduction in the energy gap (E_g) from 3.83 eV for carbon black to 3.28 eV for the AC-HNO₃ sample through activation with different acidic solvents using the solvothermal method. The FTIR spectroscopy detected several functional groups in all samples, including OH, CH₂, C=C, and CH aromatic, across all samples. According to the carbon monoxide (CO) gas sensing characterization, the AC-HNO₃ sample exhibited the highest sensitivity at S = 9.3%, while carbon black showed the lowest sensitivity at 2.1%. These results indicated that the AC-HNO₃ sample, with its high porosity, large specific surface area, and superior gas sensitivity, could have been effectively utilized in industrial applications such as water treatment, air filtration, and gas sensing.

The aim of this study was to fabricate Si₃N₄–SrTiO₃ nanomaterial-doped polystyrene (PS) to utilize in futuristic photonics and nanoelectronics applications. The structural, electrical, and optical features of PS/Si₃N₄/SrTiO₃ films were investigated. The results indicated a percentage increment of the absorption above that of PS of 90% at λ = 300 nm and 95.8% at λ = 800 nm when increasing the Si₃N₄/SrTiO₃ concentration to 6.6 wt.%. The bandgap of PS decreased from 4.22 to 2.4 eV for the allowed transition but reduced from 4.1 to 1.5 eV for the forbidden transition when increasing the Si₃N₄/SrTiO₃ nanoparticle (NP) ratio to 6.6 wt.%, a behavior that makes such materials favorable for use in many optoelectronics approaches. The optical features of the PS were improved when increasing the Si₃N₄/SrTiO₃ NP concentration, making such PS/Si₃N₄/SrTiO₃ films potential materials for use in optical fields. The dielectric properties show that the dielectric constant of PS at 100 Hz was improved from 3.34 to 4 while the alternating-current (AC) conductivity increased from 7.61 × 10^–12 to 1.78 × 10^–11 S/cm when the Si₃N₄/SrTiO₃ NP content reached 6.6 wt.%. Finally, the results confirm that such PS/Si₃N₄/SrTiO₃ films could be considered as promising materials for use in nanoelectronics and optical applications.

The frequent leakage of crude oil and the illegal discharge of industrial organic pollutants have caused serious damage to the ecological environment and the loss of valuable resources. In this paper, we introduce a sponge with magnetic and photothermal properties. Polydopamine and ferric oxide (Fe₃O₄) were grafted onto the sponge, self-assembled on the three-dimensional (3D) skeleton surface by Zif material, and grafted with cetyltrimethoxysilane to make the modified sponge highly hydrophobic (water contact angle = 155°). Moreover, due to the dual photothermal conversion properties of polydopamine and ferric oxide (Fe₃O₄), the modified sponge can be quickly heated to 110 °C under light (1.25 kw/m²). The modified sponge demonstrated excellent crude oil adsorption capacity (44 g/g) and recyclability. Due to its magnetic properties (saturated magnetization = 4.43 emu/g), derived from the incorporation of Fe₃O₄, the sponge could be remotely controlled for adsorption. Moreover, it demonstrated the ability to continuously adsorb and collect light oil from the water surface with the aid of a peristaltic pump. The sponge also functioned as an efficient filter for separating heavy oil underwater through liquid gravity, achieving a separation efficiency of 97.2%. Therefore, this composite sponge not only presents a promising solution for crude oil spill remediation but also holds significant potential for industrial wastewater treatment, making it highly relevant for practical environmental applications.

The rubber-based cable accessory always serves as the joints component for connecting two power cables due to the length limitation of a single cable, which plays a key role but possesses a high failure rate in high-voltage transmission engineering. Because the large mismatch of electrical parameters between the ethylene-propylene-diene monomer (EPDM) rubber and cross-linked polyethylene of cable main insulation induces the severe electric fields distortion at the stress cone that threatens the safe operation of cable accessory. To develop the rubber materials with excellent nonlinear conductivity property is a favorable technique to relieve the electric field concentration in cable accessory. Different from previous studies, this work utilizes organic conductive polypyrrole (PPy) rather than inorganic conductive or semi-conductive fillers to induce nonlinear conductivity of EPDM. Meanwhile, the 10wt% hexagonal boron nitride (BN) is also incorporated into EPDM for reconciling the breakdown strength of the composites according to our previous studies. The results show that incorporating PPy organic filler can induce nonlinear conductivity characteristics of the PPy/BN/EPDM composites, which become more significant with the increase of PPy doping content. At 30 °C, 50 °C, and 70 °C, the nonlinear coefficient of 5wt%PPy/BN/EPDM is increased by 36.4%, 29.9%, and 47.7% compared to 1wt%PPy/BN/EPDM, and the threshold field strength is reduced by 44.7%, 46.66%, and 37.7%, respectively. The COMSOL Multiphysics field simulation results show that using PPy/BN/EPDM composites as enhanced insulation can relieve the electric field concentration especially at the root of the stress cone, guaranteeing the safe operation of the cable accessories in the electric transmission.

Based on the advantage of large structural inclusiveness, the apatite-like borate RbSr₄(BO₃)₃:Dy³⁺,Eu³⁺ warm-white fluorescent materials have been designed using a heterovalent substitution strategy. In RbSr₄(BO₃)₃:Dy³⁺,Eu³⁺, the trivalent dysprosium and europium cations occupy the crystallization sites of divalent strontium cations. The trivalent dysprosium doped RbSr₄(BO₃)₃ exhibits bluish fluorescence with CIE color coordinates of (0.306, 0.347) and correlated color temperature of 6714 K. This is due to the blue emission originating from the ⁴F_9/2 → ⁶H_15/2 electron transition being more intense than the yellow emission derived from the ⁴F_9/2 → ⁶H_13/2 transition. Accordingly, the trivalent europium cations were incorporated into RbSr₄(BO₃)₃:Dy³⁺ to complement for the insufficient red light. Ultimately, the single-matrix warm-white fluorescent material RbSr₄(BO₃)₃:Dy³⁺,Eu³⁺ was successfully synthesized. RbSr₄(BO₃)₃:0.6%Dy³⁺,0.8%Eu³⁺ shows CIE color coordinates of (0.395, 0.344), a correlated color temperature of 3340 K, and an enhanced photoluminescence quantum yield (PLQY) of up to approximately 95.9%. This work not only provides a design strategy for novel fluorescent materials, but also endows high-performance single-component warm-white phosphors suitable for solid-state lighting applications.

Transient liquid phase (TLP) bonding is a promising electronic packaging technology to satisfy the needs of operating at high temperatures due to the increasing power density of power electronic devices. More and more power chips are finished with Ni/Ag metallization, while the top metal is Cu in direct bonded copper. However, interfacial reactions in Cu/Sn/Ag system were rarely studied. In order to explore the intermetallic reaction kinetics between solder and substrate in Cu/Sn/Ag system, this study investigated the effect of different reflow temperatures (250–350 °C) and time (30–960 s) on the microstructure evolution of the interfaces of three different TLP systems (Cu/Sn, Ag/Sn and Cu/Sn/Ag), and the growth kinetics of two intermetallic compounds (IMCs) Cu₆Sn₅ and Ag₃Sn. The results indicate that the activation energy of Cu₆Sn₅ in Cu/Sn/Ag TLP increases by 42.8% compared to Cu/Sn TLP, and the activation energy of Ag₃Sn increases by 34.1% compared to Ag/Sn TLP. During the solid–liquid process of Ag/Sn/Cu TLP, Ag atoms from the Ag substrate side will cross through the molten Sn layer to form Ag₃Sn on the surface of Cu₆Sn₅ IMCs on the Cu substrate side. Meanwhile, Cu atoms from the Cu substrate side will reach Ag substrate side to form Cu₆Sn₅ on the surface of Ag₃Sn IMCs. Heterogeneous IMCs at the interface hinder the grain boundary/melting channel for the diffusion of substrate atoms, increasing the activation energy and inhibiting their growth.

The electrolyte Li₇La₃Zr₂O₁₂ (LLZO) has emerged as a promising contender for solid-state energy storage applications. The present work uses a solid-state reaction technique to synthesize Ta-doped Li₇La₃Zr₂O₁₂ (LLZO: xTa⁵⁺) powder. The powder used to make the pellets is annealed for varying lengths of time. The impact of this process on the structural and electrical characteristics of LLZO: xTa⁵⁺ is thoroughly examined. High-resolution transmission electron microscopy (HRTEM) and selected area of diffracted light (SAED) are used to analyze the microstructural characteristics of the sintered powder, respectively. HRTEM image of LLZO indicates that after sintering, the xTa⁵⁺ powder has uniformly distributed, well-structured grains across the surface. The X-ray photoelectron spectroscopy (XPS) spectra results provide strong evidence for the existence of Ta, O, Zr, Li, and La in the synthesized electrolyte. The cyclic voltammetry results validate that 0.15 M.W.% Ta⁵⁺-doped LLZO gives a higher anodic current density (± 5 mA cm²) than pure (± 2.5 mA cm²) and 0.25 M.W.% (± 3.5 mA cm²) dopant percentage for the same potential levels. The electrochemical impedance spectroscopy (EIS) shows the lower R (resistance), whereas slanting straight line of the Nyquist plot indicates the Warburg impedance, signifying the high conductivity of the electrode. The dielectric constant and its corresponding loss, with respect to change in frequency and different temperature conditions were investigated for 0.15 M.W.% Ta⁵⁺-doped LLZO pellet.

This research investigates sol–gel auto-combustion synthesized Sr_1-xLa_xFe_12-yBi_yO₁₉ (x = 0–0.25, y = 0–0.5) nanoparticles, focusing on La³⁺ and Bi³⁺ co-substitution effects on structural and dielectric properties. X-ray diffraction confirms a single-phase M-type hexagonal ferrite structure (space group P6₃/mmc) with crystallite sizes decreasing from 20 to 13 nm and lattice parameters increasing from 682.08 to 704.73 Å upon La³⁺ and Bi³⁺ co-substitution. Field-emission scanning electron microscopy analysis reveals that the La/Bi substitution results in changes to the morphology and particle size of the samples. Dielectric properties analyzed using impedance spectroscopy reveal a decreased real part of dielectric permittivity with increasing frequency and co-substitution, attributable to interfacial polarization and microstructural changes. The imaginary parts of the electrical modulus diagram exhibit a relaxation peak shift towards lower frequencies with co-substitution, indicating enhanced charge carrier mobility and Debye dielectric response. Findings offer comprehensive insights for tailoring properties in energy storage devices, electronic components, and related fields.