Journal of Materials Science: Materials in Electronics最新文献

NIR narrowband imaging is highly desirable for its applications in biological sensing, environmental monitoring and military defense. Unfortunately, it cannot be fulfilled by the most widely used silicon-based photodetectors due to their broadband response. Herein, we present novel silicon-based narrowband photodetectors (Si-NBPDs) with the wavelength response ranging from 800 to 1200 nm, by integrating the perovskite light extinction layer with the Si-based metal–semiconductor-metal photodetectors. The perovskite layer was prepared by a low-cost and scalable methylamine-assisted blading-coating method, and its thickness was comprehensively modulated to achieve the highest visible to NIR rejection ratio up to 120. Impressively, these Si-NBPDs exhibited a high sensitivity with the lowest detectable light intensity down to 200 pW·cm⁻², a fast response speed with rise/fall time of 11/68 µs, and a large liner dynamic range of 120 dB. Furthermore, the proof-of-concept NIR imaging test exhibited that this photodetector was immune to visible background influence, which shows its promising applications in biological fluorescence imaging as the NIR-I&II windows.

An organic complex derived from 2,6-diaminopyridinium hydrogen malonate (DAPMAL) was studied for its crystal growth, structure and properties including its non-linear optical (NLO) behavior. Single-crystal X-ray diffraction (SXRD) confirmed a monoclinic crystalline structure with a C2/c (15) space group. Density functional theory (DFT) calculations using the B3LYP/6311G(d, p) approach revealed significant hyperpolarizability indicative of strong NLO behavior. The natural bond orbital analysis is performed to identify hydrogen bonding and charge transfer interaction. A combined experimental and theoretical quantum chemical calculation has been accomplished to examine the molecule’s geometry, vibrational wavenumber, electronic transition, and NLO activity. Molecular electrostatic potential and are carried out to identify chemical reactivity and charge transfer interaction. The HOMO–LUMO energy gap for DAPMAL was calculated to be 5.926 eV at the B3LYP/6-311G(d,p) level of theory. The hole–electron analysis was performed to determine the type of excitation. Reduced density gradient is performed to identify the hydrogen bonding, steric, and van der Waals interactions. Thermal analysis (TG–DTA) shows thermal stability at 185 ℃ and decomposition patterns, while SEM–EDX is used to find the material’s purity and crystalline nature. UV–visible spectroscopy demonstrated transparency with a lower cutoff wavelength of 210 nm and fluorescence spectroscopy revealed 628 nm shows red emission. The Z-scan technique further validated 3.49E-06 the compound’s NLO potential for DAPMAL.

In this work, the lithium iron phosphate (LiFePO₄) /multi-walled carbon nanotubes (MWCNTs)/ketjen black (KB)/regenerated cellulose (RC) freestanding composite electrodes were prepared by using 1-ethyl-3-methylimidazolium diethyl phosphate ([Emim]DEP) /dimethyl sulfoxide (DMSO) as the solvent system for the application of lithium-ion battery cathode. The electrodes were characterized and analyzed by Fourier transform infrared spectra (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), cyclic voltammetry (CV), electrochemical impedance spectroscope (EIS), and constant-current charge/discharge. The results indicate that the electrodes possess a three-dimensional layered network structure comprising RC and MWCNTs intertwined and lapped. The LiFePO₄ and KB particles can be inlaid and distributed on the surface of the network structure or among the pores, which enhances the multi-directionality and conduction rate of electron conduction, as well as the utilization efficiency of LiFePO₄. The electrode comprising a 3:1 ratio of MWCNTs to KB and a LiFePO₄ loading of 40 wt% performed best overall, with initial discharge specific capacities of 177.12, 143.02, and 127.12 mAh·g⁻¹ at rates of 0.1, 2, and 5 C, respectively. Moreover, the capacity retention was 99.82% after 50 cycles at 0.1 C and 94.58% after 200 cycles at 2 C. The Coulombic efficiency remained above 97% during 50 cycles at 0.1 C and above 98% during 200 cycles at 2 C. The electrodes exhibit favorable electrochemical performance and flexibility, which hopefully match the evolution of electrochemical energy storage devices toward lightweight and flexibility.

Resistive Random Access Memories (RRAMs) traditionally utilize a metal/insulator/metal architecture. This study introduces an innovative configuration employing metal/oxide-diluted magnetic semiconductors (O-DMS)/metal on flexible substrate, leveraging the enhanced performance of magnetic control in resistive switching. We investigated the structural, morphological, magnetic, and electrical properties of cobalt-doped ZnO and TiO₂ thin films, synthesized via DC magnetron sputtering. XRD measurements stablish the presence of Co₃O₄ phases in the samples of Co-doped ZnO thin films with substrate temperature (Ts) of 423 K, while Raman spectra of Co-doped TiO₂ thin film not evidencing the formation of the Co–O binary phases associated to the low substrate temperature (Ts = 293 K). High-resolution SEM and AFM analyses revealed the formation of small grains on the film surfaces, indicative of the growth mechanisms. When Co target power was increased between 20 and 40 W, the grain size increased from 158.89 ± 4.76 nm to 460.97 ± 13.82 nm. Electrical and magnetic characterizations demonstrated contributions from lattice free electrons, generated by oxygen vacancies, and randomly distributed Co ions within the oxide semiconductor matrix, influencing the SET and RESET states. Comparative analysis of ZnO and TiO₂ matrices indicated reduced energy consumption and increased storage capacity, attributed to the modulation of high and low resistive states by magnetic ions within the semiconductor matrix, associated to change between low resistive state (LRS) and HRS occurs (~ 1–3 V).

The construction of heterostructures for precise electron-transfer paths at the interface is crucial to widespread photocatalytic applications. In this context, we have implemented a simple one-step strategy to precisely transfer electrons from the conduction band of N-doped ZnO (N–ZnO) to the valence band of g-C₃N₄ by an S-scheme structure. The diverse structures and properties of the fabricated photocatalysts were synergistically verified using a series of characterization techniques. Notably, the direction of electron migration within this system was confirmed through X-ray photoelectron spectroscopy (XPS). The electrochemical impedance spectroscopy (EIS) demonstrated low charge transfer resistance, and photocurrent along with photoluminescence analyses showed enhanced spatial charge carriers separation capability of the heterostructures. Furthermore, the composite presented the cellular geometry and the long-term durability. These brought about the boosted photocatalytic performance for CO₂ reduction and norfloxacin (NOR) degradation. Specifically, the optimized composite containing 10 wt% N–ZnO (NZG-10) achieved a NOR degradation efficiency of 98.8% within 50 min, with a remarkable rate constant of 22.28 and 7.58 times that of N–ZnO and g-C₃N₄, respectively. Simultaneously, the NZG-10 was 2.98 times the CO yield of g-C₃N₄. This work offers valuable insights into developing methodologies to address the low light-harvesting capability of g-C₃N₄ and designing other novel structural materials with desirable photocatalytic performance for widespread applications in clean energy and eco-environment management.

A nickel diselenide and bimetallic nickel iron diselenide were prepared in the presence of hydrazine hydrate as a reductant by a simple hydrothermal method. The prepared composites were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), High-resolution scanning electron microscopy (HRSEM), High-resolution Tunneling electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), Vibrating sample magnetometer, and Cyclic voltammetry. The XRD confirmed the presence of cubic and orthorhombic phases of NiSe₂ and NiFeSe₂, respectively. HRSEM and HRTEM images showed the spherical morphology of both materials. This specific morphology allowed for efficient electron transfer, shortened ion diffusion pathways, and greater ion penetration into the electrode materials, which collectively contributed to enhanced electrochemical performance. The optimized NiFeSe₂ composite recorded a notable specific capacitance of 1016 Fg⁻¹ at a scan rate of 2 mV⁻¹ and its magnetic properties are indicative of antiferromagnetism.

Functional properties of oxide films largely depend upon its thickness. In conventional one-by-one thin film deposition approach, uniform deposition with single thickness is fabricated. Here, we have employed the concepts of combinatorial chemistry in pulsed laser deposition (C-PLD) system for the deposition of LaCoO₃ compound. The combinatorial PLD allows one to obtain large variations of thickness onto one substrate in a single experiment. LaCoO₃ is chosen to demonstrate the thickness dependent optical properties. Across 9 mm of substrate, more than 30 nm systematic thickness variations were achieved on a 10 mm quartz plate. Controlled mask motion with synchronised laser pulses were introduced to fabricate continuously varying film thickness across the substrate. Structural and surface properties were examined by X-ray diffraction, Raman spectroscopy and AFM respectively. Systematic variations in the electrical resistance and optical band gap were observed with film thickness. Using this unique approach, large number of samples with controlled variation in thickness can be fabricated in single experiment and can be optimized quickly for semiconductors which can be used for tuning the physical properties in RRAMs and solar cells.

Dielectric ceramic capacitors have received a great deal of attention. In this work, (1-x)[0.92Bi_0.5Na_0.5TiO₃-0.08(0.5Ca_0.3Ba_0.7TiO₃-0.5BaTi_0.8Zr_0.2O₃)]-xNaNbO₃ ceramics were prepared. The breakdown electric field of the ceramics is significantly enhanced, thanks to the rational two-phase (P4bm and R3c) coexistence structure and introduction of NaNbO₃. As a result, a recoverable energy storage density (W_r) of 3.7 J/cm³ and an efficiency (η) of 84.8% are achieved in 0.88[0.92Bi_0.5Na_0.5TiO₃-0.08(0.5Ca_0.3Ba_0.7TiO₃-0.5BaTi_0.8Zr_0.2O₃)]-0.12NaNbO₃ sample. In addition, at 160 °C, the sample has 2.8 J/cm³ of W_r and 92.1% of η at 240 kV/cm. Besides, the sample has excellent power density and rapid charge/discharge capability.

Anion doping offers a promising approach to enhance the ionic conductivity of solid electrolytes at intermediate temperatures, a key factor hindering the widespread commercialization process of solid oxide fuel cells (SOFCs). This study, for the first time, explores the influence of fluorine doping at the concentrations of 0, 5, and 10 mol% in La_0.9Sr_0.1Ga_0.8Mg_0.2O_3-δ (LSGM) perovskite structure, synthesized using the glycine-nitrate combustion method. X-ray diffraction (XRD) analysis revealed a transition from orthorhombic to monoclinic phase upon increasing the fluorine incorporation, while maintaining the tolerance factor near unity, indicating a minimal structural distortion within the GaO₆ octahedra. X-ray photoelectron spectroscopy (XPS) confirmed the successful incorporation of fluorine ions, with an associated enhancement in oxygen vacancy that contributed to improved ionic conductivity. Field-emission scanning electron microscopy (FE-SEM) studies revealed that the 10 mol% fluorine-doped LSGM (LSGMF10) exhibited the largest grain size which facilitated faster oxygen vacancy mobility. The optical measurements indicated a reduced bandgap for LSGMF10 due to the increase in oxygen vacancy concentration. Electrochemical impedance spectroscopy (EIS) demonstrated a remarkable conductivity of 3.8 mS/cm at 600 °C for LSGMF10 (0.24 mS/cm for LSGM) that can be attributed to the synergistic effects of minimal lattice distortion, reduced bandgap energy, and improved grain growth induced by fluorine doping. These findings establish fluorine doping as a promising approach for developing high-performance SOFC electrolytes at intermediate temperatures.

Two series of spinel ferrite nanoparticles Mn_0.5Zn_0.5−xCu_xFe_2−yO₄Gd_y (where x = 0, 0.05, 0.1, 0.15, 0.2, 0.25, y = 0, 0.1) synthesized using the co-precipitation method. The techniques of XRD, FTIR, SEM–EDS, TEM-SAED, and VSM were employed to investigate the microstructural, optical, morphological and magnetic properties of the nanoparticles. The XRD findings validated the establishment of a cubic spinel ferrite structure (Fd-3m space group). Crystallite size for Gd³⁺ substituted NPs was in the range of 15–24 nm and for without Gd³⁺ NPs 15–22 nm with varying Copper concentration. The characteristic absorption bands within the range of 400–4000 cm⁻¹ associated with spinel ferrite were detected using the FTIR technique. SEM examination confirmed that the ferrite particle grains are agglomerated. EDS spectra verified the presence of all included components in the composition. Morphology & size analysis was made by TEM-SAED technique where particles shown nearly spherical shape. The measured mean particle size obtained from TEM corresponds with the crystallite size calculated from XRD data. The M–H hysteresis curve was utilized to compute and evaluate the magnetic properties of nanoparticles. The saturation magnetization (M_s), coercivity (H_c), remanence (M_r), and magnetic moment, in connection to structural and microstructural characteristics. Saturation magnetization varied when the concentration of Cu²⁺ increased, from 7.1 to 43.9 emu/g for Gd³⁺ substituted samples and 4.1 to 31.32 emu/g for Gd³⁺ unsubstituted samples. The measured value of H_c is rather low, suggesting that it can be quickly demagnetized and is suitable for electromagnetic applications.