Journal of Materials Research最新文献

Magnetic properties of mixed spinel ferrites are determined, in great extent, by the magnetic cation distribution among tetrahedral and octahedral positions in a crystal. In the case of CoZn-ferrites, most researchers reported a predominant localization of the divalent cobalt ions in octahedral positions. Using the citrate precursor auto-combustion method, we successfully synthesized Co_xZn_1-xFe₂O₄ nanoparticles (x changed from 0.0 to 0.5) with an approximately evenly distribution of Co²⁺ ions between these interstitial positions. Fe³⁺ ions are localized preferably in octahedral positions. This type of 3d-ion distribution predetermined the combination of the large saturation magnetization and very low coercive field of the nanoparticles, which may be of importance for applications. MCD spectra of Co_xZn_1-xFe₂O₄ nanoparticles are studied here for the first time. Revealed intense MCD peak at 1.75 eV corresponds to the emission wavelength (710 nm) of some lasers, e.g., ALP-710 nm (NKT Photonics, Denmark) which may be of interest for photonic devices.

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Nowadays, there is significant interest in hydrogels that have injectable, self-healing, and antibacterial properties. These features make them highly desirable for use in wound dressings. In this study, a class of biocompatible nanocomposite hydrogels was designed based on oxidized tragacanth gum (OTG), N-succinyl chitosan (NSC), and silver nanoparticles (AgNPs) for biomedical applications. To obtain the nanocomposite hydrogels containing different AgNP content, we utilized silver nanoparticles at concentrations of 4, 6, and 8 mg/mL. The OTG/NSC/Ag hydrogel demonstrated superior mechanical properties compared with the OTG/NSC hydrogel without AgNP. The hydrogels also exhibited rapid gelation ( < 60 s), sufficient swelling capacity, and outstanding injectability. The hemolysis and antibacterial tests demonstrated that the produced hydrogels possess non-hemolytic and antibacterial properties. In addition, the hydrogels loaded with AgNPs exhibited low toxicity to fibroblast cells (L929), thus demonstrating acceptable biocompatibility. These findings indicated that the prepared hydrogels could be utilized as novel wound dressing materials.

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In this study, AuM (M = Pt, Pd) bimetallic hexagonals (AuM BHGs) were successfully combined with graphene quantum dots (GQDs) by a simple method at ambient temperature (~ 30 °C) to form AuM BHGs/GQDs nanocomposites with enhanced properties and electro-activities. The synthesized AuM BHGs/GQDs were also characterized by UV–Vis, XRD, FTIR, XPS, AFM, TEM, and EDS. The novel AuM BHGs/GQDs were successfully synthesized, possessed an average particle size of AuM BHGs (~ 50–60 nm) and GQDs (~ 6–16 nm), and were homogeneously distributed in the dispersion. Furthermore, AuM BHGs/GQDs nanocomposites were also investigated as a sensitive sensor in the H₂O₂ detection by cyclic voltammetry method, with a low H₂O₂ limit of detection (LOD) of 0.865 nM, high sensitivity of 1.27 μAnM⁻¹cm⁻² and a wide detection range from 10^–12 to 10^–3 M. Therefore, AuM BHG/GQDs nanocomposites could be used to detect H₂O₂ with high sensitivity and fast response.

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The present study aims to develop a systematic processing route using direct ink writing (DIW) and pressureless sintering for fabricating hierarchically porous (text{ Cu }) (HP-(text{ Cu })) electrodes. A 3D printable high particle loading (text{ Cu }) ink (> 95 {text{wt}}%) with polylactic acid as a binder was prepared. Green ({text{Cu}}) samples using optimum value of (text{ Cu }) loading, nozzle diameter, layer height, and printing speed as 97 ({text{wt}}%), 0.2 (text{mm}), 70% and 10 (text{mm}/text{s}) respectively were fabricated and subsequently sintered. A proper inter-particle bonding with 91% relative density and 215 (text{Mpa}) ultimate compressive strength was achieved. Finally, a proof-of-concept study targeting the fabrication of thin HP-(text{ Cu }) current collector was performed and the pore size of 154 ± 10 µm with a thickness of 200 µm was achieved successfully. Moreover, the prepared sample exhibited the highest coulombic efficiency of 95.86% for more than 400 h at 1 ({text{mAcm}}^{-2}) making it a potential candidate for energy storage applications.

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In the paper, a high-performance electrode was reported for the determination of uric acid (UA) and dopamine (DA) by loading nanocomposites Fe₂O₃/poly-neutral red (PNR)/partially reduced graphene oxide (rGO) on glassy carbon electrode (GCE). The nanocomposites Fe₂O₃/PNR/rGO were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectrometer (FTIR), and electrochemical impedance spectroscopy (EIS). Under the optimized condition, the peak currents of UA and DA showed good linear relationships with their concentrations in the range of 1 × 10^–6 to 1 × 10^–3 mol L⁻¹ and 3 × 10^–7 to 9 × 10^–5 mol L⁻¹, respectively. The recovery rates were 93.0–102.0% and 99.2–104.6% for detecting DA from medical injections and human specimens, including urine and serum, respectively, 95.5–105.0% for UA from urine and serum samples. Obviously, this Fe₂O₃/PNR/rGO/GCE is expected to be used in production quality control and clinical test.

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Implementing sensitive and fast formaldehyde (HCHO) sensing at room temperature is still in extreme demand for practical indoor air quality monitoring. Herein, we synthesized P25/ZnO sensing materials for detecting low-concentration HCHO at room temperature. The sensing mechanism based on the P25/ZnO heterojunction was analyzed by the surface photovoltage (SPV), transient photovoltage (TPV), and X-ray photoelectron spectroscopy (XPS) results. Based on the P25/ZnO heterojunction, the obtained 1% P25/ZnO has the highest response among the synthesized sensing materials. The response of 1% P25/ZnO sensor materials to 0.9ppm and 19.1ppm HCHO reaches 44.85% and 255.42%, respectively, which is 21 and 20 times that of ZnO sensor materials (0.9ppm ~ 2.16%, 19.1ppm ~ 12.64%). Furthermore, the detection limit can be as low as 82 ppb under 360 nm light at room temperature. The selectivity, long-term stability, and repeatability of the obtained sensors at room temperature were also revealed.

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In this work, the characteristics of MoS₂ and its nanocomposite with SnO₂ for photocatalytic degradation of methylene blue have been investigated. The MoS₂ and MoS₂/SnO₂ nanocomposites were synthesized by the hydrothermal method. SEM analysis shows the flower-like structure of MoS₂ while MoS₂/SnO₂ nanocomposites shows grain-like structure. The EDX analysis of the MoS₂ and MoS₂/SnO₂ nanocomposites confirm the samples were mainly composed of Mo, S, Sn, and O atoms and the XRD patterns confirm hexagonal and rhombohedral phases, respectively. The FTIR spectra indicate the presence of both hydroxyl and carboxyl functional groups at the sample's surface. The UV–Visible spectroscopy findings witness both samples are being active in the visible range. Further, the band gap estimation through Tauc plot supports the assertion that these materials could be an efficient catalyst for photodegradation. Furthermore, the photodegradation of methylene blue (used as a dye) findings declare the maximum efficiency of 93% by using MoS₂/SnO₂ nanocomposite as a catalyst.

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The current study focused to synthesize magnesium (Mg²⁺) and bismuth (Bi³⁺) co-doped bioactive glass (BG) nanoparticles (NPs) at ambient conditions. XPS studies confirmed the existence of Mg²⁺ as MgO and Bi³⁺ as Bi₂O₃ in co-doped BG NPs. XRD reported an increase in mean crystallite size from 0.1 ± 0.01 nm to 0.25 ± 0.04 nm with 0.5 to 1.5 mol% increase in Bi₂O₃ content. TGA revealed co-doping of Mg²⁺ and Bi³⁺ to BG NPs increased their thermal stability by 20 to 30 w/w% in comparison to the control. FTIR and NMR studies depicted open SiO₂ network in co-doped BG NPs. HR-TEM evidenced co-doped BG NPs were of ~ 50 nm. The optical transmittance showed strong emission peak at 480 nm for co-doped BG NPs with decreased intensity with increasing Bi³⁺ ion concentration. In-vitro bioactivity, hemolysis and MTT assay revealed excellent bone binding ability, least toxicity and excellent biocompatibility.

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Cu reflow behavior was studied on various metal liners, including Co, Ru, Ta, Ti, and W. These investigations provide insight into the differences in surface diffusion characteristics of Cu along these metal liner interfaces, as revealed by structural characterization using various electron microscopy imaging techniques. In addition, the electrical properties of these metal liner/Cu stacks were investigated as a function of annealing time by evaluating changes in sheet resistance, to understand the extent to which Cu films remain continuous. Atomic force microscopy, transmission electron microscopy, and scanning electron microscopy observations provided insight into the dimensions of Cu islands formed during thermal annealing. On Ta and Ru liners, Cu surface diffusion was found to be most prominent. Compared to Ta and Ru, more Cu islands were formed per area for Co liner, exhibiting a reduced average Cu island size. Only minimal Cu island formation was observed for Ti and W liners.

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In the controlled atmosphere of a dedicated glove box, nanoindentation performed with a diamond Berkovich indenter tip has been used to examine the mechanical behavior of three (oxy)sulfide solid-state electrolytes (SSEs), 70Li₂S·(30−x)P₂S₅·xP₂O₅ (x = 0, 2, and 5). At a drive frequency of 120 Hz, the elastic modulus is found to be predominantly depth independent over the range of 100 nm to 1 μm and generally insensitive to the varying mol fraction of oxygen (0, 2, and 5%) as well as the imposed strain rates of 0.025, 0.05, and 0.1 1/s. All three SSEs exhibit significant room-temperature creep. Strain burst activity observed during loading (potentially representative of pore collapse or cracking) is attenuated with the addition of oxygen. The hardness is found to be insensitive to the imposed strain rates but varying with depth and oxygen content. The highest oxygen concentration yields the lowest hardness and strongest depth dependence.

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Nanoindentation of monolithic (oxy)sulfide glass solid-state electrolytes in an inert environment yields rate and depth dependent behavior.