Journal of Materials Science: Materials in Electronics最新文献

Flexible strain sensors are widely applied in medical diagnosis, electronic skin, health detection, and human movement. It is urgent to develop a flexible sensor with simple structure, ultra-low detection limit, excellent sensitivity, and broad detection range. Herein, a flexible strain sensor possessing a double-layered conductive network involving a porous polydimethylsiloxane (PDMS)/multiwalled carbon nanotubes (MWCNTs) and a silver nanowire (AgNW) is obtained. The porous PDMS/MWCNTs films are prepared by curing the PDMS/MWCNTs/NaCl mixture and dissolving the NaCl powder. By depositing different amount of AgNWs on the surface of PDMS/MWCNTs layer to prepare the high conductivity AgNWs, generating the low initial resistance. Due to the synergistic effects of the double-layered conductive network, the flexible strain sensor possessing a very high sensitivity (up to 221.2) and a very wide working range (up to 100%) is obtained. In addition, this sensor has a fast response (110 ms) and excellent dynamic stability (6000 cycles). In practical applications, the as-obtained sensor can accurately monitor the human motions and physiological signals, proving great potential application value in human motion detection. This work provides a new approach for developing high-performance flexible strain sensors.

Magnetic nanoparticles have attracted significant attention in medical applications because of their enhanced biocompatibility and multifunctional properties. They support advanced drug delivery, nanotheranostics, and in vivo imaging. This study examines how different capping agents, including ascorbic acid (AA), tartaric acid (TA), lauric acid (LA), and malic acid (MA), influence the structure and magnetic performance of zinc-doped (Zn_0.75Fe_2.25O₄) nanoparticles, aiming to identify effective tracers for Magnetic Particle Imaging (MPI). All samples exhibited superparamagnetism with M_s = 40–52 emu/g (300 K) and high colloidal stability (zeta potential − 26.9 to − 52.8 mV). The MA-coated sample delivered the strongest MPS response with the highest 5th/3rd harmonic ratio (0.49) and the narrowest PSF FWHM (8.16 mT), compared to AA- (0.31; 10.89 mT), TA- (0.40; 9.57 mT), and LA-(0.29; 8.38 mT) coated samples. This study demonstrates that controlled Zn²⁺ doping combined with tailored surface chemistry via specific organic coatings can effectively tune the structural and magnetic properties of ferrite nanoparticles toward high-resolution MPI performance, indicating that appropriately capped Zn-ferrite nanoparticles are promising candidate tracers. However, in vivo and in vitro validation and benchmarking against established agents are still required.

In this study, the 2-PHMBD Schiff base, synthesized through the condensation of 2,4-dihydroxybenzaldehyde (2,4-DHBA) with phenylhydrazine (PH), was subjected to oxidative polymerization in a basic medium using hydrogen peroxide (H₂O₂), sodium hypochlorite (NaOCl), and molecular oxygen (O₂) as oxidizing agents. Three oligomers, designated as o-(2-PHMBD)-P, o-(2-PHMBD)-H, and o-(2-PHMBD)-O, were successfully obtained and comprehensively characterized by FT-IR, ¹H-¹³C-NMR, UV–Vis, CV, GPC, SEM, TGA, and DSC analyses. Spectroscopic results confirmed the successful polymerization, while morphological and thermal analyses revealed the distinct physical characteristics of the oligomers. According to GPC data, o-(2-PHMBD)-H exhibited the highest average molecular weight of 4700 Da, and TGA analysis demonstrated that o-(2-PHMBD)-O had the highest thermal stability with a residue of 46% at 1000 °C. The DSC results showed the highest glass transition temperature of 132 °C for o-(2-PHMBD)-H. UV–Vis and CV measurements indicated reduced optical and electrochemical band gaps compared with the monomer, with the lowest optical band gap determined as 2.74 eV. Dielectric measurements revealed that o-(2-PHMBD)-H displayed the highest dielectric constant of 2.57 and conductivity of 2.49 × 10⁻⁷ S cm⁻¹. These results demonstrate that phenylhydrazine-based Schiff base oligomers possess high thermal stability and favorable dielectric properties, making them promising materials for optoelectronic and dielectric device applications.

The issue of electromagnetic interference caused by low-frequency communication devices is becoming increasingly severe. To address this challenge, we prepared fumed silica-loaded nickel-zinc ferrite composites. The composites were synthesized via a sol–gel method. The structure, morphology, and electromagnetic wave absorption properties of samples with varying ratios of fumed silica (FS) to nickel-zinc ferrite (Ni_0.5Zn_0.5Fe₂O₄) were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and a vector network analyzer (VNA). The results indicate that the incorporation of fumed silica broadens the absorption bandwidth in the low-frequency range (2–6 GHz). The reflection loss of pure nickel-zinc ferrite reached –20.55 dB at 7.56 GHz, while the FS/Ni_0.5Zn_0.5Fe₂O₄ composite achieved a superior reflection loss of –22.46 dB at the same frequency, demonstrating the beneficial effect of fumed silica addition.

The effect of post-bond annealing on the quantitative interfacial adhesion energy of low-temperature Cu–Cu bonding interfaces was systematically investigated using a double cantilever beam test. A two-step Ar/N₂ plasma treatment was applied to achieve low-temperature bonding. This treatment protected the Cu surface from oxidation by forming Cu nitrides such as Cu₃N and Cu₄N, which were confirmed via electron backscatter diffraction and X-ray photoelectron spectroscopy analyses. Cu₃N and Cu₄N completely decomposed at 200 °C, enabling pure Cu–Cu low-temperature bonding. The interfacial adhesion energy at post-bond annealing temperatures of 250 °C, 300 °C, and 350 °C was 0.65 ± 0.05 J/m², 3.81 ± 0.61 J/m², and 4.12 ± 1.12 J/m², respectively. As the post-bond annealing temperature increased, Cu atomic diffusion was enhanced, leading to the elimination of voids and seams, grain growth, and the disappearance of grain boundaries. Consequently, the improved Cu‒Cu bonding quality resulted in an increase in interfacial adhesion energy.

With the rapid advancement of electronic communication technologies, electromagnetic pollution and interference from various electronic devices pose risks to both the environment and human health. As a result, research on electromagnetic shielding materials is intensifying. New electromagnetic shielding materials can be produced cost-effectively using biomass carbon materials. This study prepared corn cob-based carbon materials at 700 °C using four methods: direct carbonization, KOH-activated carbonization, Fe^3⁺/Fe^2⁺ impregnation carbonization, and a combined KOH activation Fe^3⁺/Fe^2⁺ impregnation method. The combined-method material exhibited the best overall electromagnetic shielding performance among all the carbon materials. The carbon powder, with a thickness of 1.1 mm, showed the lowest reflection loss of − 26.63 dB at 3.09 GHz, with a − 15 dB bandwidth of 1.85 GHz. Regarding shielding effectiveness, the material maintained a value below − 15 dB across the 1–6 GHz range, with a − 20 dB bandwidth of 2.14 GHz. The minimum value of − 34.17 dB occurred at 2.64 GHz. Compared to the directly carbonized sample, the sample carbonized using the combined method effectively combined the pore-forming capability of KOH activation with the magnetic loss from Fe₃O₄ nanoparticles. The electromagnetic shielding and absorption performance of the combined-method material was well explained by its electromagnetic parameters, particularly the total electromagnetic loss tangent.

In response to the increasing demand for high‐performance supercapacitor and hydrogen production electrode materials, this article focuses on synthesis and electrochemical testing of WS₂ nanosheets, Mo₂C (MXene), and WS₂/MXene nanocomposites as hybrids. Carbon nanotubes (CNTs) are being of great interest in the energy storage application area as a result of their outstanding capacity for storage, sensitivity, and conductivity. 3 wt.% of CNT was added to the composite, resulting in the CNT@WS₂/MXene hybrid structure. The aim is to design next-generation materials with enhanced energy storage properties. Toward this end, a comparative study was done on the nanocomposite and its individual building blocks. The synthesis of MXene, WS₂ nanosheets, and their nanocomposites was completed using a combination of chemical etching and hydrothermal techniques. In this work, abundant active sites were combined with high conductivity to rationally design a CNT@WS₂/Mo₂C hybrid architecture for enhanced energy storage and hydrogen evolution. Furthermore, through the combination of CNT@WS₂/Mo₂C and activated carbon, a hybrid supercapacitor is designed as CNT@WS₂/Mo₂C//AC. At 2 Ag⁻¹, the hybrid device exhibited a Qs value of 410 C/g. In addition, the hybrid supercapacitor demonstrated a significantly higher energy density (75.9 Wh/kg) and power density (1000 W/kg) than the values that had been previously reported. The device’s stability is evaluated by measuring it for up to 12,000 charging/discharging cycles. The real device maintained 86.8% of its capacity retention and coulombic efficiency of 95.1%. In addition, the CNT@WS₂/Mo₂C material demonstrates a low overpotential of 98.7 mV at − 10 mA/cm², along with Tafel slope values of 77.62 mV/dec for the HER, and it exhibits excellent cyclic stability. Our research establishes a novel foundation for the development of energy storage devices that are of the supercapacitor type and exhibit exceptional performance. The modification of CNT@WS₂/Mo₂C electrode presents novel opportunities for the development of high-performance energy storage devices and electrochemical water splitting.

The practical application of Ga₂O₃ photodetectors is constrained by low responsivity, long decay time, and external power reliance, whereas Nb₂CT_x MXene demonstrates a high work function and intrinsic solar-blind UV selectivity. Integrating Nb₂CT_x with Ga₂O₃ to form a suitable heterostructure offers a promising solution for significantly enhanced photodetection performance. Herein, a new type of self-powered photoelectrochemical (PEC) solar-blind UV photodetector has been constructed based on the heterostructure composed of β-Ga₂O₃ nanoarray rods and few-layered Nb₂CT_x via hydrothermal growth, post-annealing, spin-coating, and thermal processing. The photoelectric properties of the devices have been evaluated systematically. The results show that the β-Ga₂O₃/Nb₂CT_x heterojunction photodetector exhibits stable self-powering ability and typical solar-blind UV response characteristics. Under 254 nm UV light illumination at 0 V bias, the device achieves a photo-to-dark current ratio of 36.6 ± 4.85, responsivity of 2.4 ± 0.18 mA/W, and specific defectivity of (3.12 ± 0.16) × 10¹⁰ Jones, showing 3.2, 2.3, and 4.1 times higher than those of pristine β-Ga₂O₃ device. Moreover, the β-Ga₂O₃/Nb₂CT_x heterojunction photodetector has a faster response speed, with a rise/decay time of 2.1 s/0.6 s. The improved photoresponse properties of the device are attributed to the built-in electric field established by the β-Ga₂O₃/Nb₂CT_x heterojunction, which can facilitate the transportation of photogenerated carriers and suppress electron–hole recombination. The present work not only extends the application of Nb₂CT_x MXene, but also provides a new tactic to improve the performance of Ga₂O₃-based photodetector.

The nanoscale spinel structure of n-type lead aluminate (PAS) provides synergistic effects from its composite components, resulting in a tunable band gap for carrier excitation and charge transport upon interaction with black-light irradiation. In the present paper, the PAS was prepared using a Co-precipitation synthesis method. The organized specimen was primarily characterized using different efficient analysis methods. Then, for the first time, an ultraviolet light photodetector based on PAS (UPA) has been developed to detect and annotate various power densities of 365nm-UV light (P_Ds). I-V characteristics of the UPA showed that the net current is affected by the changes in temperature, bias voltage, and UV light P_D. The UPA offered low-dark current, acceptable ideality factor, and a modified Richardson constant of 48.47 A.cm⁻².K⁻². Furthermore, it exhibited nonlinear asymmetric rectification behavior, high contrast ratio near zero volts, and meaningful short-circuit current at 0 V, indicating its self-powered nature. The study of the I_Ph-t characteristics of the device revealed repetitive stability, acceptable R_Ph (2.182 A/W), good D^* (4.06 × 10¹¹ Jones), high EQE (740.68%), NG (24.24 W⁻¹), and LDR of 54.54 dB at the P_D of 2.2 mW/cm². In addition, the UPA exposed a t_R of 4 s, I_MPh of 17 µA, and NEP of 24.39 W.Hz^−0.5 at P_D of 79.6 mW/cm². The stability of the R_Ph and D^* over three months indicates that the dark current in the UPA is controlled and minimized. In conclusion, the possible mechanism in the device operation was debated in detail by employing a standard thermionic emission–diffusion model and energy band diagrams.

The development of high-performance microwave absorbers requires a deep understanding of the synergistic effects between cation doping in ferrites and carbon nanotubes (CNTs). To this end, a series of trivalent metal ions (Al³⁺, Cr³⁺, Fe³⁺, Ga³⁺, In³⁺)-doped Ni_0.6Zn_0.4M_0.2Fe_1.75O₄ ferrites and their composites with 7 wt% CNTs were systematically synthesized. Among the pure ferrites, the Ga³⁺-doped sample showed the best performance (RL_min = − 31.58 dB at 4.3 mm). Critically, the introduction of CNTs substantially enhanced the absorption performance, as evidenced by a broadened effective bandwidth and reduced reflection loss, which ultimately led to a distinct shift in the optimal system. The In³⁺-doped ferrite/CNT composite emerged as the superior absorber, achieving an RL_min of − 46.83 dB at a thinner thickness of 2.98 mm, markedly outperforming all other composites and the premier single-phase ferrite. This work reveals the distinct roles of various dopants in tuning intrinsic electromagnetic properties and demonstrates that the enhancement via CNTs stems from a balanced dielectric/magnetic loss and optimized impedance matching. The most effective synergy was uniquely realized in the In³⁺-doped system, highlighting its significant potential as a high-performance microwave-absorbing material.