Journal of Materials Science: Materials in Electronics最新文献

This work was conducted to examine the electrical conductivity and permittivity of epoxy/CVD grown carbon nanofiber composites, focusing on how these properties vary with frequency and the volume fraction of the filler used. Nested cone structure carbon nanofibers (CNFs) synthesized over Ni/Al₂O₃ catalyst in a vibrofluidized bed reactor served as filler. Electrical properties of epoxy/CNF composites were investigated with the wide volume fraction range (ϕ= 0–0.224) and across a frequency spectrum ranging from 0.05 Hz to 10⁶ Hz at 25°C. The objective was to relate the experimental findings and compare them to theoretical models for assessing the electrical properties (e.g., two-exponent phenomenological percolation equation; general rule of mixtures; model based on Fermi-Dirac distribution, and others), both AC and DC, of “conductor-insulator” composites. The R² coefficient of the experimental DC conductivity of the epoxy/CNF composites ranged from 0.789 to 0.984, depending on the theoretical model used for fitting. To describe the AC conductivity and permittivity of epoxy/carbon nanofiber composites concerning filler volume fraction and frequency, both the general rule of mixtures and two-exponential phenomenological percolation equations were evaluated. It was observed that the electrical characteristics are strongly influenced by factors such as the shape of the filler, as well as its aggregation and distribution within the polymer matrix. A newly modified general rule of mixtures was proposed to effectively represent the experimental data on conductivity and permittivity in relation to frequency and the volume fraction of CNFs, based on the morphology of CNF aggregates.

2-Bromo-6-chloro-4-nitroaniline (C₆H₄BrClN₂O₂) crystals have been successfully synthesised by solution evaporation technique. Single crystal XRD is used to verify its structure like monoclinic system and P2₁/c space group. Functional groups were identified by Fourier Transform Infrared (FT‑IR) spectroscopy. Optical transmittance was examined using Ultraviolet–Visible (UV–Vis) spectroscopy, giving a band‑gap energy of 4.14 eV for calculated 4.1 eV for Tauc’s plot. Thermal stability was evaluated by Thermogravimetric Analysis (TGA), showing the material remains stable up to 137 °C. Mechanical testing indicated that BCN is a relatively soft organic crystal. Electrical properties and Laser Damage Threshold (LDT) were also assessed. Quantum‑chemical calculations, including Highest Occupied Molecular Orbital–Lowest Unoccupied Molecular Orbital (HOMO–LUMO) and Molecular Electrostatic Potential (MEP) analyses, complemented the experimental findings, and theoretical Nonlinear Optical (NLO) parameters were computed. Z‑scan (Z‑scan) measurements confirmed third‑order NLO activity with reverse‑saturation absorption and a positive nonlinear refractive index. These results position BCN as a promising candidate for optoelectronic and NLO device applications.

In this study, ZnO_x thin films were deposited by RF magnetron sputtering under varying oxygen partial pressures, with O₂/(O₂ + Ar) ratios ranging from 10 to 40%. X-ray diffraction (XRD) confirmed the formation of a hexagonal wurtzite ZnO phase, with the O₂/(O₂ + Ar) ratio significantly influencing crystallinity and growth orientation. Optimal structural quality was achieved at a ratio of approximately 20%. Energy-dispersive X-ray spectroscopy (EDS) and scanning electron microscopy (SEM) revealed improved stoichiometry and the development of a columnar microstructure with increasing O₂/(O₂ + Ar) ratio. Atomic force microscopy (AFM) showed a pronounced reduction in surface roughness, reaching a minimum at 20–25%. Optical transmittance peaked at 84.25% for films deposited at a 25% O₂/(O₂ + Ar) ratio, accompanied by a direct optical band gap of ~ 3.14 eV. Photoluminescence (PL) spectra showed enhanced near-band-edge UV emission and diminished defect-related visible emissions under optimal oxygen conditions. Electrical measurements indicated increasing resistivity and decreasing carrier concentration with higher O₂/(O₂ + Ar) ratios. Maximum Hall mobility and figure of merit were observed at a 25% O₂/(O₂ + Ar) ratio. These findings highlight the crucial role of oxygen content in the plasma gas mixture for tailoring ZnO_x thin films toward advanced optoelectronic applications.

Aluminum (Al)-doped zinc oxide (AZO) films were prepared via atomic layer deposition at 250 °C to explore the impact of Al content on their optical, structural, and electrical characteristics. X-ray diffraction patterns indicated that the films crystallized in a hexagonal wurtzite phase exhibiting prominent diffraction peaks corresponding to the (100), (002), and (101) planes. Among these, the (002) plane was the preferred orientation, suggesting that the AZO films possessed a strong c-axis alignment perpendicular to the substrate. With increasing Al dopant concentration, all diffraction peaks exhibited a systematic shift toward higher angles, accompanied by a reduction in crystallinity. This adverse effect, however, was effectively mitigated by extending the purge duration during deposition. Following parameter optimization, the resulting AZO film demonstrated an impressively low resistivity (~ 1.90 × 10⁻⁴ Ω cm), together with significant enhancements of approximately 13% in carrier concentration and 11% in carrier mobility.

Present work deals to investigate the effect of finite-size particles pertaining to structural, morphological, magnetic, and magneto-optical behaviour. The structural, morphological, and magnetic investigation were done using XRD, Transmission electron microscopy (TEM) and vibration sample magnetometer (VSM) techniques, respectively. The particle size varies in the range of 7 to 15 nm. The dislocation density of atoms and strain varies with the particle size. A focused study on the magneto-optical tunability with intensity-induced refractive index was examined using novel in-house magneto-optical experimental technique at 25°C. The nonlinear refractive index coefficient is found to be of the order of 10⁻³. Also, size and concentration-dependent variation of nonlinear refractive index coefficient is observed. Significant optical multiple diffraction rings of the fluid under green laser illumination with different size and concentrations were observed. The sample with 1% concentration has the best limiting effect among the other two concentrations. Field-induced anisotropy and modulating magneto-optical response profiles in nanomagnetic fluid shows the potential application in magnetic sensors, magneto-optical switches, optical limiters, etc.

As a typical superconducting material, PbMo₆S₈ (PMS) exhibits many advantages, such as high critical field, low fabrication cost, etc. Therefore, it has attracted the attention of researchers. With in its lattice, sulfide plays a pivotal role in the phase composition, microstructure, as well as superconducting properties. In this study, PbMo₆S_x bulks with different S content have been successfully synthesized using the solid-state sintering method. It reveals that single phase PMS can be achieved within the S content of 7.8–8.0. And Pb, Mo and MoS₂, Pb appear respectively, when the S content was deficient or excessive. Furthermore, variations in S content influence the superconducting transition temperature (T_c) and the flux pinning force density (F_p) of PbMo₆S_x samples, which consequently results in alterations to the critical current density (J_c). With the S content of 7.8, the maximum T_c value of 12.5 K and the highest critical current density (J_c) of over 30 kA/cm² were obtained. This work proves that with the optimization of fabrication process, PMS with high superconducting properties can be achieved as promising practical superconductors.

In this study, we synthesized Ni-Zn bimetallic metal–organic frameworks (Bi-MOFs) and first investigated their performance as saturable absorbers (SAs) in passively Q-switched erbium-doped fiber lasers (EDFLs). Two samples of Ni-Zn Bi-MOF-SAs were synthesized using two distinct organic linkers: methyl-imidazole (MIM) and benzene-1,3,5-tricarboxylic acid (BTC). The prepared materials were characterized using X-ray diffraction (XRD) to determine their structural properties and Fourier-transform infrared spectroscopy (FTIR) to identify the functional groups. Field-emission scanning electron microscopy (FE-SEM) revealed well-defined microcrystalline morphologies, while EDX spectra and elemental mapping confirmed the uniform elemental composition and homogeneous distribution within the prepared Ni–Zn Bi-MOF samples. The prepared MIM and BTC linker-based Ni-Zn Bi-MOFs yielded a modulation depth of 11.28% and 6.65%, respectively. Once prepared, SAs integrated within the laser cavity, the measured experimental results showed that the EDFL with the MIM-based Ni-Zn Bi-MOF-SA achieved an emission wavelength of 1559.88 nm, a repetition rate of 121 kHz, a pulse width of 3.98 μs, and an average output power of 2.55 mW at a maximum pump power of 312.5 mW. In contrast, the EDFL with the BTC-based Ni-Zn Bi-MOF-SA generated an emission wavelength of 1560.12 nm, a repetition rate of 75.3 kHz, a pulse width of 6 μs, and an average output power of 4.55 mW at the same pump power. Furthermore, the stability of both MIM- and BTC-based Ni-Zn Bi-MOF-SAs was evaluated for one hour at a fixed pump power of 104.6 mW. Measurements of average power, repetition rate, and pulse width during stability testing confirmed the reliability and robustness of the Ni-Zn Bi-MOF-SAs. This study demonstrates that the Ni-Zn Bi-MOFs are well-suited SAs for pulsed laser sources, highlighting their potential in telecommunications and material processing.

Ferroelectric materials are widely regarded as promising candidates for sustainable energy technologies, particularly in solid-state cooling and energy storage applications. In this work, the microstructural, dielectric, electrocaloric, and energy storage properties of Na_0.5Bi_0.5Hf_0.4Ti_0.6O₃ (NBHT) ceramics were systematically investigated. X-ray diffraction (XRD) analysis confirmed the coexistence of monoclinic and tetragonal phases, with an enhanced tetragonal contribution observed at higher sintering temperatures. Increasing the sintering temperature facilitated grain growth, improved densification, and significantly enhanced the dielectric and ferroelectric responses. The NBHT ceramic sintered at 1100 °C exhibited a maximum electrocaloric temperature change (ΔT) of 0.35 K and a recoverable energy density (W_rec) of 1.32 J cm⁻³ with an energy efficiency of approximately 80% at 120 °C. In contrast, the sample sintered at 1200 °C demonstrated a W_rec of 1.56 J cm⁻³ and high efficiency of 80% under an applied electric field of 40 kV cm⁻¹. These findings reveal that the NBHT ceramics exhibit a strong electrocaloric effect coupled with excellent energy storage performance, underscoring their potential as lead-free ferroelectric materials for next-generation solid-state cooling and energy storage devices.

SnO₂ thin films were prepared using a dip-coating sol–gel process on the glass substrates with different precursor molar concentrations (0.3, 0.6, 0.8 and 1 M). X-ray diffraction (XRD) analysis showed that all samples are polycrystalline and crystallize in a tetragonal rutile structure. With the increase of the molarity, the crystallite size increased. The molarity strongly dictates the film texture, with clear changes in the preferred growth orientation (quantified by ({text{TC}}_{text{hkl}})).UV–visible optical measurements indicated that all films are highly transparent (∼ 84–87% in the visible region) upon annealing at 500 °C. The optical band gap exhibited an apparent blue shift up to a concentration of 0.6 M, reaching a value of 3.82 eV, followed by a slight decrease at higher concentrations. It is noteworthy that a minimum refractive index of 2.133 was also observed at the same concentration. AFM analysis shows that the 0.6 M film presents the lowest surface roughness, a condition that correlates with the maximum band gap and reduced light scattering at low molarities transmittance. Room temperature photoluminescence studies showed broad UV emission with intensity being dependent on the molarity of the precursors. Hall Effect measurement revealed an n-type conduction for all samples. Among them, the 0.6 M-prepared film showed the lowest resistivity (0.186 Ω·cm), the highest conductivity (5.56 (Ω·cm) ⁻¹) and the best figure of merit (4.9 × 10⁻⁵Ω⁻¹). Finally, The 0.6 M film has been identified as a sweet spot that compromises on nanostructures, wide bandgap, high transparency, and excellent optoelectronic performances, rendering it a promising candidate for transparent electronics and optoelectronics.

The advancement of effective and eco-friendly cooling technology is essential for tackling global energy sustainability and climate change issues. This work presents a thorough analysis of the magnetic phase transition and magnetocaloric effect in the as-cast and annealed LaFe_11.2Si_1.8 ribbons made via melt spinning, revealing the significant influence of annealing on their magnetic and magnetocaloric characteristics. Annealing dramatically modifies the structure by a rapid peritectic reaction, enhancing the volume fraction of the 1:13 phase and reducing the secondary phase, α-Fe phase. This leads to significant improvements in the Curie transition temperature, working temperature, and relative cooling power. The Curie transition temperature rises from 244 to 254 K, with the working temperature and relative cooling power enhancing by 236% and 592%, respectively. The findings emphasise the essential function of annealing in enhancing the magnetic characteristics of La(Fe,Si)₁₃ compounds and highlight their promise for sustainable and efficient magnetic refrigeration.