Journal of Materials Research最新文献

This study evaluated the chemical, mechanical, and biocompatibility of Portland cement (PC) with different proportions of niobium oxide (Nb₂O₅). Five male Wistar rats were used. Four polyethylene tubes were placed on the dorsal subcutaneous tissue: one tube empty (NC), one tube MTA (Angelus®), one tube contained F6 (PC, Nb₂O₅ and CaSO₄), and one tube F7 (PC, Bi₂O₃, Nb₂O₅ and CaSO₄). After 60 days, animals were euthanized, and tubes were removed with the surrounding tissues. Inflammatory infiltrates were stained with hematoxylin–eosin. Mineralization was analyzed using Von Kossa staining and polarized light. The F6 showed small vessels and dispersed mononuclear inflammatory cells, score of 1 (1–2), p˃0.05 vs. NC 0.5 (0–1), and the absence of cell giants. Positive Von Kossa staining and birefringent structures under polarized light were observed with MTA, F6, and F7. The niobium oxide (Nb₂O₅), in association with Portland cement, exhibits calcium crystals and biocompatibility in rat subcutaneous tissue.

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A worm-like oxide Ca₃Co₂O₆ was prepared by electrostatic spinning as a cathode material for solid-oxide fuel cells. Compared to the plain granular structure, the worm-like Ca₃Co₂O₆ exhibits a desirable morphological organization and an enhanced electrochemical performance. At 1073 K, polarization resistance with the worm-like cathode is favorably reduced to 0.151 Ω cm², and the power peak of the corresponding single cell reaches to 512 mW cm⁻², showing a fast cathodic kinetics. By contrast, the polarization resistance with the plain cathode is 0.275 Ω cm², and the power peak of the corresponding single cell is 406 mW cm⁻². Under a constant voltage load of applied 0.6 V at 1023 K, cell power with the worm-like cathode maintains steadily from 420 to 400 mW cm⁻² after 14 h of running time, showing a less fading rate, a more stable performance, and a better application prospect than the plain cathode.

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Electrostatic spinning of Ca₃Co₂O₆ as the cathode material of solid-oxide fuel cells.

Zinc (Zn) and its alloys exhibit great potential for utilization in biodegradable bone implants. Zn-1Cu biodegradable alloy was produced and were cold rolled at two different deformation rates of 47 and 61%. The samples have been bioceramic coated with the sol–gel method and microstructure-mechanical property changes, corrosion behavior and biocompatibility of the samples were investigated. They were characterized by Optical, SEM, XRD and wettability analysis. The rolled samples showed a significant increase in hardness when compared to the non-rolled samples. The unrolled and 47% rolled samples showed better corrosion resistance compared to 61% rolled samples. Antibacterial effects of the base and sol–gel-coated groups showed higher cell viability ratios than the uncoated groups. Cell viability increased significantly in 47% of the rolled samples after 24, 48, and 72 h, however decreased by up to 70% in 61% of the rolled samples.

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Neuromorphic hardware promises to revolutionize information technology with brain-inspired parallel processing, in-memory computing, and energy-efficient implementation of artificial intelligence and machine learning. In particular, two-dimensional (2D) memtransistors enable gate-tunable non-volatile memory, bio-realistic synaptic phenomena, and atomically thin scaling. However, previously reported 2D memtransistors have not achieved low operating voltages without compromising gate-tunability. Here, we overcome this limitation by demonstrating MoS₂ memtransistors with short channel lengths < 400 nm, low operating voltages < 1 V, and high field-effect switching ratios > 10⁴ while concurrently achieving strong memristive responses. This functionality is realized by fabricating back-gated memtransistors using highly polycrystalline monolayer MoS₂ channels on high-κ Al₂O₃ dielectric layers. Finite-element simulations confirm enhanced electrostatic modulation near the channel contacts, which reduces operating voltages without compromising memristive or field-effect switching. Overall, this work demonstrates a pathway for reducing the size and power consumption of 2D memtransistors as is required for ultrahigh-density integration.

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Magnesiothermic reduction was applied to porous silica glass grains with a characteristically interconnected pore structure. The prepared porous silicon maintained the morphology with pore size of approximately 30–40 nm, which was derived from the nanostructure of the starting silica glass. Medium-sized grains of the silica glass produced the largest silicon yield. This result could be explained based on the diffusion-controlled reaction mechanism, involving the reaction of SiO₂ with Mg₂Si to produce silicon. The electrochemical behavior was investigated using a coin-type cell composed of the prepared porous silicon–carbon mixtures and lithium foil electrodes. The initial charge and discharge capacities reached 1382 and 1187 mAh g⁻¹, respectively, which were close to the theoretical value (1329 mAh g⁻¹). After 50 charge/discharge cycles, 80% of the initial capacity is maintained. These results indicate that porous silicon derived from porous silica glass can be employed as an anode material for lithium-ion batteries.

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Mg−3.18Al−1.00Zn−0.06Mn(wt.%) (AZ31) alloy was fabricated through a combination of hot die forging at 300℃ and extrusion processes (HFE). Results demonstrate that the HFE process can accelerate dynamic recrystallization (DRX) and refine grains effectively while weakening the basal texture intensity. The highly uniform fine grain structure of the HFE sample was attributed to hot die forging treatment prior to extrusion, which facilitates the nucleation of recrystallization and improves the microstructure. After 60 s of hot die forging, the HFE sample exhibited promising mechanical properties. In particular, yield asymmetry ratio (σCYS/σTYS) improved significantly by 30%. This work provides a new research strategy for obtaining Mg alloys with high economic benefit and satisfactory comprehensive performance.

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The structural, electronic, and thermoelectric properties of Nb-based metal oxides XNb₂O₆ (X = Mg, Ca, and Ba) have been investigated using DFT and experimental methods for energy harvesting applications. The XRD confirmed the orthorhombic structure of the synthesized oxides. SEM observed the formation of well-shaped particles, and the presence of Mg, Ca, Ba, Nb, and O with the proper compositions was confirmed by EDS. TEM proved the polycrystalline nature of sample BaNb₂O₆. The metal oxides MgNb₂O₆, CaNb₂O₆, and BaNb₂O₆ showed band gaps of 2.19 eV, 2.13 eV, and 0.90 eV, respectively. The calculations of the total and partial density of states were carried out to examine the effects of atomic orbitals on the formation of bands. The BoltzTraP algorithm within the Wien2k code was used to study the novel transport properties. The productive values of the figure of merit suggest that the studied materials are suitable for thermoelectric applications.

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In this study, glass transition and crystallization of Ce₆₈Al₁₀Cu₂₀Co₂ bulk metallic glass at heating rates ranging from 0.083 to 14,000 K/s, covering six orders of magnitude, are investigated. For the glass transition, two linear regions with different apparent activation energies (E_a,g) are distinguished by a critical heating rate of 2000 K/s: E_a,g decreases from 208.7 to 67.3 kJ/mol with the increase of heating rate. During the crystallization, the nucleation rate and crystal growth rate between T_g and T_m are calculated. According to their dependence on temperature, the contact angle for the nucleation of Ce crystals is estimated at 11–14 degrees. For the crystal growth, a maximum crystal growth rate of 0.03 m/s is found at 0.97 T_m. Moreover, the breakdown of the Stokes–Einstein equation in the deeply undercooled melt is observed, where the diffusivity is related to viscosity by D ∝ η^−0.865.

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Expanded polystyrene spheres (EPS) were coated by SiO₂–TiO₂ or TiO₂ for application as a fluidized bed in the photocatalytic reactor. Silica coating was realized by the sol–gel process carried out in a vacuum evaporator at 60–70 °C. The most uniform and thin layer of silica coating was obtained by the Stöber method based on the hydrolysis of tetraethyl orthosilicate (TEOS) catalysed by an ammonia solution. Effective TiO₂ coating was obtained by the immersion of EPS in the titania aqueous suspension and evaporation of water in a vacuum evaporator. Heating of EPS spheres coated by SiO₂, TiO₂ or SiO₂–TiO₂ at the temperatures of 120–140 °C resulted in a shrinkage of their volume. For the thick layer coating, a strong corrugation of EPS surface was observed. The photocatalytic tests showed, that highly corrugated surface of coated EPS slowed down ethylene decomposition, whereas a thin layer coating of both, SiO₂ and TiO₂ was advantageous.

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The present study investigated drug-loaded, titanium alloy (Ti6Al4V) graded porous structure with desired mechanical properties for implant-based local drug delivery application. The fabricated graded porous metallic structures displayed compressive yield strength in a range of 110.8–283.8 MPa, open porosity 30.2–69.4% and Young’s modulus 2.2–12.1 GPa. These characteristics resemble the range for human bone tissue. The electrochemical corrosion behaviour of the fabricated structures was found satisfactory even though comparatively higher corrosion rate was observed in porous samples. The analysis showed the formation of protective passive layer on the exposed surface of the porous samples. The micrographs confirmed the presence of well-distributed interconnected pores in the peripheral region of the samples which were used to load drug (simvastatin) using different dispersion media. It was found that by varying the later, the in vitro release of loaded drug can be prolonged to as long as 14 days.

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