Journal of Materials Science: Materials in Electronics最新文献

MoS₂ thin films were successfully formulated using the spray pyrolysis technique and investigated for their structural, optical, electrical and gas sensing characteristics. The precursor-based formulation produced uniform nanocrystalline MoS₂ layers, as confirmed by XRD, FESEM and EDX analyses, revealing a well-defined hexagonal phase, nanoscale grain morphology and near-stoichiometric Mo:S ratio. Optical studies indicated strong UV–visible absorption and a direct band gap of 2.11 eV, consistent with semiconducting behavior. Electrical measurements demonstrated stable temperature-dependent conductivity and suitable activation energies for gas sensing applications. The MoS₂ thin films exhibited excellent sensing performance, with LPG showing the highest sensitivity among all tested gases. A maximum sensitivity of 91.96% was achieved at 60 °C for 200 ppm LPG, supported by fast response (6 s) and recovery (51 s) times, along with good reusability and long-term stability over six weeks. The enhanced LPG selectivity is attributed to the strong interaction between sulfur-containing LPG components and sulfur-rich active sites on MoS₂. These results highlight the potential of spray-pyrolyzed MoS₂ thin films as efficient, low-temperature, and highly selective gas sensing materials for practical LPG detection applications.

Detecting nitrogen dioxide (NO₂) at low concentrations and under ambient conditions remains a significant challenge in environmental sensing. In this work, we report a highly responsive TiO₂/PEDOT nanocomposite sensor engineered through a facile in situ polymerization approach. The composite integrates the high surface reactivity of n-type TiO₂ nanoparticles that provide superior conductivity and ambient operability of p-type PEDOT, forming a synergistic p–n heterojunction that enables efficient charge separation and signal amplification at room temperature, without the need for thermal activation or extrinsic dopants, thereby distinguishing this system from previously reported TiO₂–polymer composites. Comprehensive material characterization confirmed successful nanocomposite formation and favorable structural properties. The sensor demonstrated a high response of 119.9% at 400 ppm when exposed to NO₂ gas, with recovery and response times of 137 s and 117 s, respectively, all at room temperature. Furthermore, the device showed excellent repeatability, reproducibility across sensor batches, and operational stability over 30 days. These results show that the TiO₂/PEDOT nanocomposite, which combines sensitivity, selectivity, and practicality, is a potential option for NO₂ sensing systems.

With the rapid development of 5G/6G mobile communication technology, microwave dielectric materials are facing increasingly strict performance requirements. As core fundamental materials for modern communication systems, performance optimization of microwave dielectric ceramics has become a research hotspot. Addressing the limitations of single-phase ceramic materials, dense microwave dielectric ceramics of (Nd_1-xLa_x)₂[Zr_0.89(Bi_0.5Ta_0.5)_0.11]₃(MoO₄)₉ (x = 0.01, 0.03, 0.05, 0.07) were prepared by the conventional solid-state reaction method. The experimental process involved 550 °C pre-sintering followed by gradient sintering at 600–725 °C (4 h holding time). X-ray diffraction (XRD) analysis confirmed that all samples exhibited trigonal crystal structure with (Roverline{3} c) space group. The lattice parameters were obtained by Rietveld refinement method. Scanning electron microscopy (SEM) characterization indicates that compactness has a significant impact on the dielectric constant (ε_r) and the quality factor (Q × f). Raman spectroscopy analysis indicated strong associations of ε_r and Q × f values with characteristic peak shifts and full width at half maximum (FWHM), respectively. When sintered at 675 °C, the NLZBTM (x = 0.03) ceramics exhibited exceptional comprehensive performance: ε_r = 11.24 ± 0.02, Q × f = 116,914 ± 5738 GHz, and τ_f = − 37 ± 1.5 ppm/℃. The bond property analysis based on the P–V–L theory shows that the ionicity of the Nd/La–O bond makes the greatest contribution to εᵣ, while the covalency of the Mo–O bond significantly affects the Q × f value and τ_f parameter. It is noteworthy that this material achieves low-temperature sintering at 675 °C while maintaining excellent microwave dielectric properties, demonstrating significant potential as a candidate material for low-temperature co-fired ceramics (LTCC).

Two new π-conjugated systems, an aza[4]helicene derivative (HL1) and a thiophene-based olefin (HL2), were synthesized in high yields (60–80%) under mild and cost-effective conditions. Their structures were confirmed by ¹H and ¹³C NMR, FT–IR, and HRMS analyses. Both compounds display strong UV–Vis absorption (λ_max = 378–405 nm) and intense blue-to-green fluorescence with large Stokes shifts (3779–4448 cm^–1), reflecting extended π-conjugation. The materials were subsequently applied to screen-printed carbon electrodes (SPCEs) to develop electrochemical sensors for dopamine (DA) and D–tyrosine (Tyr). The modified electrodes were characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Both HL1- and HL2-based SPCEs enabled simultaneous detection of DA and Tyr in the presence of uric acid (UA) as an interferent. Notably, HL2/SPCE exhibited superior analytical performance, offering a wide linear response range (0–500 µM), low detection limits (0.7022 µM for DA and 0.6274 µM for Tyr), and high sensitivities of 0.645 µA µM^–1 cm^–2 and 0.256 µA µM^–1 cm^–2, respectively. These findings highlight its potential for preliminary biosensing applications and provide a promising platform for further optimization toward real biological sample analysis.

The single crystal of SnBi₄Te₄—a member of n(Bi₂)∙m(SnBi₂Te₄) homological series and potential candidate material with nontrivial topology was grown by the modified Bridgman method and characterized by X-ray diffraction (XRD), scanning electron microscopy with an energy dispersive X-ray spectrometer (SEM–EDX), and X-ray photoelectron spectroscopy (XPS). High single-crystalline quality of the grown crystal without any signs of surface contaminants detectable by SEM–EDX and XPS was confirmed by XRD. According to the results of Rietveld analysis of the XRD data, a trigonal structure with the P-3m1 space group symmetry and a stacking sequence of atomic layers similar to that of the 9P polytype crystal structure of GeSb₄Te₄ is inherent to SnBi₄Te₄. The crystal structure is built up from 7-layer rocksalt-type slabs, alternated with bismuth bilayers, with van der Waals (vdW) bonding between the two. Raman spectroscopy and spectroscopic ellipsometry (SE), complemented and supported by ab-initio calculations, provided the core information regarding the lattice dynamics and dielectric function of SnBi₄Te₄, as well as preliminary insight into possible functionalities of the grown material.

This article deliberates the analysis of some optical, electrical, and structural parameters of Ag_x(As_0.33Se_0.335Te_0.335)_100−x glasses synthesized from cascade heating method. Optical measurements have been performed to determine optical band gap using Tauc’s plots and to discuss the obtained values in the context of Ag doping influence. AC conductivity measurements were made over the frequency domain of 30 Hz to 20 kHz with the temperature interval from 293 to 353 K. The optical band gap decreases from ~ 0.65 eV (for x = 0) to ~ 0.55 eV at 7 at.% Ag, confirming band-gap narrowing due to Ag-induced defect states. However, at higher Ag contents (9–13%), the band-gap trend deviates, with E_g saturating around ~ 0.5 eV. This indicates significant structural modifications at high doping, while AC conductivity follows the correlated barrier hopping model. Frequency response of AC conductivity was investigated to identify the credible conductivity mechanism and to explore the potential of different roles of Ag dopant in amorphous matrix depending on various concentrations. Activation energy exhibits a non-monotonic dependence on Ag concentration, decreasing for highly doped samples (x ≥ 7 at.%) and suggesting a transition in the dominant conduction mechanism. Impedance spectra were recorded aiming to provide more details about the conduction mechanism and to highlight the role of silver doping. The obtained results revealed single depressed semicircular Nyquist arcs for 0–5% Ag glasses, consistent with one predominant relaxation process, whereas glasses with ≥ 7% Ag exhibited an additional low-frequency tail and second arc. The EIS spectrum analysis showed requirement of a second R||CPE element branch for the Ag-rich compositions, reflecting the emergence of Ag⁺ ion diffusion pathways at high doping. The use of more complex equivalent circuits in description of impedance response of the samples with x ≥ 7 at.% corresponds with assumption of Ag-rich microdomains formation. The EDS analysis was conducted to explore the spatial distribution of silver across the sample surfaces and confirmed a transition from heterogeneous to uniform Ag distribution with increase in silver content (x ≥ 7 at.%).

Hard magnetic magnetoplumbite-type SrFe₁₂O₁₉ ferrite is widely used due to its fine chemical stability, high cost-effectiveness and good magnetic properties. Figuring out the phase-morphology evolution and magnetic properties during annealing at high temperatures is essential for establishing structure–property relationships for SrFe₁₂O₁₉ ferrites. In this study, a traditional ceramic method was used to prepare SrFe₁₂O₁₉ ferrites using cubic α-Fe₂O₃ nanoparticles obtained via a hydrothermal method as Fe sources, and the phase-morphology evolution and magnetic properties at different annealing stages were studied. With the increase of annealing temperature, the morphology changes of cubic α-Fe₂O₃ accompanied with the phase evolution were found to critically determine the magnetic properties. A morphology model was built to elaborate the relationship between phase-morphology and magnetic properties for SrFe₁₂O₁₉ ferrites. It was found that the specimen annealed at 1100℃ exhibited the best comprehensive magnetic properties in this study, whose saturation magnetization and coercivity are 68.89 emu/g and 256.34 kA/m, respectively.

Piezo-photocatalysis is regarded as a promising strategy to suppress the rapid recombination of photogenerated charges. Herein, a novel (Ba_0.95,Ca_0.05)(Ti_0.90,Sn_0.10)O₃-xAg₂O (BCTS-xAg₂O) heterojunction was fabricated via a facile chemical method to harness the piezoelectric effect under ultrasonic vibration for a remarkable enhancement of catalytic performance. The BCTS-0.01Ag₂O composite achieves a remarkable 99.5% degradation of RhB within 120 min under concurrent light and ultrasonic excitation. This corresponds to a reaction rate constant (k) of 0.04407 min⁻¹, which surpasses those of individual BCTS and Ag₂O by factors of 5.54 and 8.64, respectively. The enhanced catalytic performance is primarily attributed to the effective separation of photogenerated electron–hole pairs in the BCTS-Ag₂O heterojunction by the built-in piezoelectric field of BCTS. This study not only delivers a high-performance BCTS-Ag₂O catalyst but also sheds light on the precise design of efficient piezo-photocatalysts.

The intense growth of modern information and communication technologies including 5G and 6G systems strengthens the demand for substrate materials whose dielectric properties ensure very high signal transmission speed and are simultaneously feasible as low- or ultra-low-temperature cofired ceramics (LTCC/ULTCC) to attain progress in miniaturization and the reduction of fabrication costs. In this study, lithium tungstate Li₂WO₄ and lithium metaborate LiBO₂ were investigated as multifunctional materials capable of performing a dual role, both as ULTCC single-phase substrates and as sintering aids for the LTCC substrates based on the CuB₂O₄ ceramic. The materials were characterized using a heating microscope and differential thermal analysis to examine sintering behavior, THz time-domain spectroscopy to explore dielectric properties, and XRD and SEM methods to reveal the phase composition and microstructure. Both Li₂WO₄ and LiBO₂ exhibited ultra-low sintering temperatures of 590–650 °C and advantageous dielectric properties, a low relative permittivity of 4.5–5.5 and a low loss tangent of 0.008–0.01 at 1 THz. As additives, both compounds significantly reduced the sintering temperature of the CuB₂O₄ ceramic by 80–90 °C, simultaneously showing a small impact on its good dielectric properties at THz frequencies.

Bismuth selenide (Bi₂Se₃), a layered chalcogenide, is a promising thermoelectric material whose performance is strongly influenced by the densification method. In this study, nanostructured Bi₂Se₃ was synthesized and consolidated using cold pressing, hot pressing, and spark plasma sintering methods. The structural, electrical, and thermal transport properties of the samples were systematically evaluated. Temperature-dependent Hall measurements provided insight into carrier concentration and mobility. The hot-pressed sample exhibited the highest mobility of 576 cm²/V s, which is ~ 41 and 51% higher than that of the cold-pressed and spark plasma sintered samples, attributed to an increased mean free path. The temperature-dependent electrical conductivity and Seebeck coefficient were analyzed, revealing a maximum power factor of 552.7 μW/mK² at 550 K for the hot-pressed sample. A low total thermal conductivity of 0.51 W/mK at 403 K was observed for the cold-pressed Bi₂Se₃ sample. Acoustic phonon scattering was indicated by weighted mobility fitting, which yielded temperature dependencies of T^−1.31 and T⁻¹ for the cold-pressed and hot-pressed samples. Our findings suggest that the hot-pressed Bi₂Se₃ sample exhibited an improved thermoelectric figure of merit (zT) of 0.18 at 510 K.