A multifunctional composite was strategically designed to simultaneously address thermal management and electromagnetic interference (EMI) shielding challenges in next-generation high-performance electronics. The composite was fabricated by filling a three-dimensional nickel foam with a waterborne polyurethane (WPU) matrix containing BN nanosheets and core–shell (FeCoNiMgMn)3O4@Ag fillers. Microstructural characterization confirmed uniform dispersion of BN nanosheets and successful Ag immobilization onto the high-entropy oxide surface. The optimized Ni/WPU-BN composite achieved a thermal conductivity of 0.91 W/m · K, nearly threefold enhancement over pristine WPU. It was found that the high-entropy oxide could improve impedance matching, facilitating greater electromagnetic wave penetration into the material for dissipative absorption. Concurrently, the Ni/WPU-BN-(FeCoNiMgMn)3O4@Ag composite exhibited an excellent EMI shielding effectiveness of 67.2 dB with absorption as the dominant mechanism. And finite element simulations further validated the experimental shielding trends. This work presents a promising dual-network strategy for advanced electronic packaging materials with integrated thermal and electromagnetic functionalities.
Energy storage nanotechnology is an emerging area of research and unlocking challenges for the sustainable development of robust materials. Spinel ZnMn2O4 architectonics have been synthesized via a one-pot ultrafast autoflame method at room temperature. The as-prepared material was characterized by various spectroscopic techniques, i.e., XRD, Raman, XPS, SEM, and so on. XRD spectra revealed that average crystallite size of 18.40 nm was calculated with intense peak (200). The particle size was found to be around 50–70 nm, as confirmed by HRTEM analysis. Furthermore, agglomerated irregular polyhedron morphology and the presence of Zn, Mn, and O elements were also validated through FESEM and elemental mapping with an Mn-to-Zn ratio of 2:1. Electrochemical CV, GCD, and EIS spectra were conducted with three-electrode system in 1M Na2SO4 electrolyte. The cyclic stability of the as-prepared electrode was evaluated over 5000 galvanostatic charge–discharge (GCD) cycles result in specific capacitance of 1475 F g-1 at a current rate of 1 A g-1 and reached to 178 F g-1 with a capacity retention of 86
Ba1-xSnxTiO3 (x = 0.01, 0.025, 0.05, 0.075) piezoelectric ceramics were synthesized by the conventional solid-state reaction method to study how A-site Sn substitution affects phase transitions, microstructure, dielectric behavior, and electrical transport in BaTiO3. X-ray diffraction confirmed a single-phase perovskite structure with no detectable secondary phases, indicating successful incorporation of Sn into the Ba site. FESEM micrographs showed dense polycrystalline microstructures with well-defined grains, and grain homogeneity improved at intermediate Sn concentrations. Temperature- and frequency-dependent measurements of dielectric constant, impedance, and dielectric loss (RT: 400 °C) showed a broad ferroelectric-to-paraelectric transition with pronounced frequency dispersion. Increasing Sn-content converted the sharp dielectric anomaly typical of BaTiO3 into a diffuse transition and improved dielectric stability over a wide temperature range. Dielectric loss stayed low at higher frequencies but rose at elevated temperatures, consistent with thermally activated charge carriers and interfacial polarization. Impedance analysis presented a negative temperature coefficient of resistance (NTCR) behavior, confirming thermally activated conduction and a drop in grain-boundary resistance with increasing temperature. These results show that A-site Sn substitution changes the phase-transition behavior and dielectric response of BaTiO3 in ways relevant to high-temperature capacitor and energy-storage applications.
Boron-rich EuB6+δ thin films were grown on Al2O3 (0001) single-crystal substrates via magnetron sputtering. X-ray diffraction and energy-dispersive X-ray spectroscopy analyses confirmed that the EuB6+δ films comprise amorphous boron and polycrystalline EuB6 with preferred orientation along the [100] crystallographic direction. The presence of excessive amorphous boron significantly modifies the magnetotransport and magnetic properties. Notably, temperature-dependent resistance measurements demonstrated semiconductor-like electronic transport characteristics, with a pronounced resistance increase during cooling from 25 to 1.8 K. Furthermore, the films exhibited negative magnetoresistance whose magnitude progressively enhanced with decreasing temperature in the same temperature range (25–1.8 K). These transport phenomena present a striking contrast to those observed in bulk EuB6 single crystals and are primarily attributed to the presence of semiconducting amorphous boron that spatially separates ferromagnetic conducting EuB6 grains and thus contribute to additional resistance and tunneling magnetoresistance effect at grain boundaries. Magnetic characterization revealed unsaturated ferromagnetic hysteresis loops at low temperatures (≤ 10 K), which are attributed to the superposition of paramagnetic contributions from amorphous boron and intrinsic ferromagnetic ordering within the polycrystalline EuB6 phase.
The sustainable utilization of industrial waste for advanced energy-storage materials has attracted increasing attention in recent years. In this study, we valorized SiO2-rich nickel slag (NS) as an electrochemically active component and combined it with reduced graphene oxide (rGO) to fabricate low-cost composite electrodes for supercapacitor applications. We synthesized the rGO/NS composites via a simple ultrasonication-assisted route at different rGO-to-NS mass ratios (0.50:0.50, 0.70:0.30, and 0.85:0.15). Structural characterization confirmed the successful incorporation of silica-rich NS into the rGO framework while preserving the graphitic structure and forming interconnected porous architectures. Increasing the rGO content increased the specific surface area from 3.63 to 7.02 m2 g−1 and the pore volume from 0.014 to 0.025 cm3 g−1, improving electrolyte accessibility. As a preliminary evaluation, we investigated the composite electrodes’ electrochemical performance in a three-electrode configuration using 1 M H2SO4 via cyclic voltammetry (CV), galvanostatic charge–discharge (GCD), and electrochemical impedance spectroscopy (EIS). Among the electrodes investigated, rGO/NS0.70 exhibited the most favorable electrochemical performance, achieving a specific capacitance of 403.64 F g−1 at a scan rate of 5 mV s−1 determined by CV and 493.60 F g−1 at a current density of 0.1 A g−1 determined by GCD, along with the lowest polarization resistance (Rp) of 20.87 kΩ and the most ideal capacitive behavior among the investigated electrodes. These preliminary findings show that SiO2-rich NS is a promising, sustainable precursor for rGO-based composite electrodes and provide a scientific basis for further validation in practical two-electrode supercapacitor devices.
