Search

For HEO@PPy composites, there are mainly eddy current loss and hysteresis loss in the high-entropy oxides. For the effect on the magnetic loss performance, it is weakening for Fe, Ni, and Co successively. The composite of HEO(1)-FeNi@PPy has the largest reflection loss with a minimum RL value of −32.04 dB and an effective absorption bandwidth of 5.8 GHz, and the corresponding thicknesses are almost the same, which enables the optimization of both parameters simultaneously. The sample also has the optimal waveband-thickness absorption characteristics. A reciprocal relationship was found between magnetic loss and dielectric loss. By incorporating the HEO(1)-FeNi@PPy powder into paraffin, it was found that the greater the amount of powder material, the higher the electric conduction loss and polarization loss, and the magnetic loss would decrease. The microwave frequency f was found to be the main variable affecting the magnetic permeability and dielectric constant. • The effect on the magnetic loss of HEOs is weakening for Fe, Ni, Co successively. • There is a reciprocal relationship between magnetic loss and dielectric loss. • Increasing HEO@PPy content can enhance the electric conduction loss and polarization loss, and decrease the magnetic loss. • Microwave frequency f is the main variable affecting the magnetic permeability and dielectric constant. [ABSTRACT FROM AUTHOR]

Graphitic carbon nitride (g-C 3 N 4) is a promising photocatalyst for photocatalytic field, but how to construct an efficient g-C 3 N 4 nanosheet-based heterostructure is still a challenge by one-step method. In this study, we prepared WO 3-x /2D g-C 3 N 4 heterostructure by one-step calcination approach, which simultaneously produced g-C 3 N 4 nanosheet, heterostructure and oxygen vacancy. The photoactivity of WO 3-x /2D g-C 3 N 4 heterostructure was tested by removing Rhodamine B (RhB), tetracycline (TC) and S. aureus under LED light illumination. The enhanced photoactivity is attributed to the promoted transfer of charge carriers, the broadened light absorption and the increased surface area of composite, which arose from heterostructure, oxygen vacancy and g-C 3 N 4 nanosheet, respectively. This study offers insights into one-step preparation for new photocatalysts in environmental field. • WO 3-x /2D g-C 3 N 4 heterostructure was prepared by one-step calcination. • WO 3-x /2D g-C 3 N 4 can remove RhB, TC and S. aureus under a LED light. • Oxygen vacancy, 2D g-C 3 N 4 and heterostructure are beneficial for the photoactivity. • Oxygen vacancy assisted Z-scheme mechanism was presented. [ABSTRACT FROM AUTHOR]

In this work, the NdFeB ribbons (Nd 13.5 Fe 73 Co 7·5 B 6 ) were first subjected to the hydrogenation disproportionation (HD) to prepare disproportionation Nd Fe B precursor and subsequently cryomilled for different times. The submicron NdFeB particles with ultrafine nanocrystalline were finally obtained after desorption recombination (DR) process. The results indicated that with the increase of the cryomilling time, Nd 2 Fe 14 B grains were refined to nanoscale, but the coercivity decreased due to the strong exchange coupling between the nano-grains. The optimized nanocrystalline NdFeB particles have a size of 40 nm or less and present a coercivity of 6.63 kOe after cryomilling for 10 h followed by DR treatment at 800 °C for 10 min. To further improve the magnetic properties, Ca was added into HD powders in the course of cryomilling process to protect the powders from oxidation and a noticeable coercivity of 9.49 kOe was obtained. Finally, the mechanism of magnetic interactions and coercivity enhancement were discussed. [ABSTRACT FROM AUTHOR]

Abstract: The temperature dependence of electrical resistivity (ρ–T) of a Sn–0.7Cu (wt.%) melt was measured and an abnormal change was found on the ρ–T curve within the range of 825–1066°C. The result suggests that the melt has experienced a temperature-induced liquid–liquid structural transition (TI-LLST), and the transition is reversible after the first cycle heating. Based on the result of TI-LLST, solidification experiments and spreadability tests were carried out on the Sn–0.7Cu alloy to investigate the effect of liquid structure transition on solidification microstructure and wettability. The results show that the microstructure was refined and the wettability was improved when the samples solidified from the melt experienced TI-LLST. [ABSTRACT FROM AUTHOR]

The grain orientation-dependent lattice strain evolution of a (TiZrHfNb) 98 N 2 refractory high-entropy alloy (HEA) during tensile loading has been investigated using in situ neutron diffraction. The equivalent strain-hardening rate of each of the primary < hkl >-oriented grain families was found to be relatively low, manifesting the macroscopically weak work-hardening ability of such a body-centered cubic (BCC)-structured HEA. This finding, along with the post-mortem transmission electron microscopy (TEM) characterization, is indicative of a dislocation planar slip mode that is confined in a few single-slip planes and leads to in-plane softening by high pile-up stresses. In particular, during plastic deformation, the <110>-oriented grains yield preferentially, followed by lattice relaxation, while the load transfers to the <200>-oriented grains as a result of plastic anisotropy. Our work provides a new perspective for understanding the strain-hardening behavior and the role of planar slip in the plastic deformation of BCC-structured HEAs. • The deformation behavior of a HEA was studied by in situ neutron diffraction. • The micro- and macro-scopic strain hardening rate relationship was articulated. • The HEA exhibits a planar slip mode and leads to in-plane strain softening. [ABSTRACT FROM AUTHOR]

A much simplified buffer structure, including a three-layer stack of LaMnO 3 /MgO/composite Y 2 O 3 –Al 2 O 3 , was proposed for high performance YBa 2 Cu 3 O 7-δ (YBCO) coated conductors. In this structure, biaxially textured MgO films were prepared on solution deposition planarized amorphous substrate through ion-beam-assisted deposition (IBAD) technology. By the use of in situ reflection high-energy electron diffraction monitor, X-ray diffraction and atomic force microscope, the influence of deposition parameters, such as film deposition rate, ion penetrate energy and ion beam flux, on crystalline orientation, texture, lattice parameter and surface morphology was systematically investigated. Moreover, stopping and range of ion in mater simulation was performed to study the effects of ion bombardment on MgO films. By optimizing IBAD process parameters, the best biaxial texture showed ω -scan of (002) MgO and Φ -scan of (220) MgO yield full width at half maximum values of 2.4° and 3.7°, indicating excellent biaxial texture. Subsequently, LaMnO 3 films were directly deposited on the IBAD-MgO template to improve the lattice mismatch between MgO and YBCO. Finally, YBCO films grown on this simplified buffer template exhibited a critical current density of 2.4 MA/cm 2 at 77 K and self-field, demonstrating the feasibility of this buffer structure. [ABSTRACT FROM AUTHOR]

• The long-term natural aging characteristics of the VO X films were studied in details. • Aging was found to cause a dramatic change in surface composition rather than optical properties. • An aging mechanism involving interface aging and diffusion aging was proposed. • The results provided valuable information for improving the atmospheric durability of VO X films. We experimentally investigate the long-term atmospheric durability of thermochromic vanadium oxide (VO X) films. The VO X films were deposited on glass substrates by reactive direct current magnetron sputtering and were then in-situ annealed at the preparation temperature ≤350 °C. The X-ray photoelectron spectroscopy (XPS) was applied to investigate the surface compositions of the natural aged films, while the optical properties of the films were characterized by the spectrophotometer and spectroscopic ellipsometry. The XPS results reveal that the oxygen-deficient VO X (X < 2.5) components possessing remarkable chemical changes is preferred to react with the O 2 and H 2 O in the air and become high oxidation state compounds. However, it is worth to note that the optical properties of the films shows extra-low variation performance (e.g. linear increasing rate of transmittance ~0.00448% per day @ λ = 600 nm). The aging mechanism of the VO X films in air was interpreted in terms of the interface aging and the diffusion-reaction aging on basis of the above experimental results. This study would provide valuable experience of the natural aging of VO X films. [ABSTRACT FROM AUTHOR]

Metallic bismuth as a promising anode for alkali metal-ion batteries has attracted great attentions because of superb volumetric capacity (3800 mA h cm−3) and suitable working voltage plateaus (∼0.5 V). However, Bi anode suffers from large volume change during repeated cycling, resulting in poor cycle performance. In this contribution, Bi nanoparticles embedded in N-doped carbon materials (Bi@N-C) are designed and fabricated by one-step pyrolysis method. Thanks to the synergistic effects of Bi nanoparticles and the N-doped carbon framework, the elaborately designed Bi@N-C can not only reduces the ion/electron diffusion pathways and enhances the reaction kinetics, but can also availably inhibits the agglomeration of Bi particles, and effectively alleviates the volume fluctuation. As an anode material, the Bi@N-C exhibits advanced rate capability (219 mA h g−1 at 5 A g−1) and excellent stable cycle ability (307 mA h g−1 at 1 A g−1, after 400 cycles) in sodium-ion batteries. Furthermore, the Bi@N-C anode also exhibit good stable cycle ability (240 mA h g−1 at 1 A g−1, after 70 cycles) in potassium-ion batteries. This study provides a facile and environmentally friendly way for fabricating high performance Bi anodes towards SIBs and PIBs. • The material preparation process is facile and large-scalable. • N-doped carbon accelerates the reaction kinetics and relieves the swelling of bismuth nanoparticles during the cycle process. • Bi@N-C shows excellent rate performance for SIBs and good cycle stability for PIBs. [ABSTRACT FROM AUTHOR]

Metallic bismuth as a promising anode for alkali metal-ion batteries has attracted great attentions because of superb volumetric capacity (3800 mA h cm−3) and suitable working voltage plateaus (∼0.5 V). However, Bi anode suffers from large volume change during repeated cycling, resulting in poor cycle performance. In this contribution, Bi nanoparticles embedded in N-doped carbon materials (Bi@N-C) are designed and fabricated by one-step pyrolysis method. Thanks to the synergistic effects of Bi nanoparticles and the N-doped carbon framework, the elaborately designed Bi@N-C can not only reduces the ion/electron diffusion pathways and enhances the reaction kinetics, but can also availably inhibits the agglomeration of Bi particles, and effectively alleviates the volume fluctuation. As an anode material, the Bi@N-C exhibits advanced rate capability (219 mA h g−1 at 5 A g−1) and excellent stable cycle ability (307 mA h g−1 at 1 A g−1, after 400 cycles) in sodium-ion batteries. Furthermore, the Bi@N-C anode also exhibit good stable cycle ability (240 mA h g−1 at 1 A g−1, after 70 cycles) in potassium-ion batteries. This study provides a facile and environmentally friendly way for fabricating high performance Bi anodes towards SIBs and PIBs. • The material preparation process is facile and large-scalable. • N-doped carbon accelerates the reaction kinetics and relieves the swelling of bismuth nanoparticles during the cycle process. • Bi@N-C shows excellent rate performance for SIBs and good cycle stability for PIBs. [ABSTRACT FROM AUTHOR]

Water electrolysis for hydrogen production requires highly active and inexpensive catalysts. Herein, we combine ultrasonic impact nanocrystallization (UIN) technology with nital etching method to rapidly prepare highly efficient self-supporting Cu electrode with abundant low-angle grain boundaries. When used as a catalyst for hydrogen evolution reaction (HER), the as-prepared electrode exhibits an overpotential of 353 mV at a current density of 10 mA cm−2, which is about 200 mV lower than that of the blank Cu plate. Moreover, the overpotential decreased to 246 mV after the stability test of 100 h, indicating a self-optimizing property. This work paves a new way for the preparation of self-supporting electrode with high performance. • Ultrasonic impact nanocrystalline could be used in catalysis. • Cu self-supporting electrode with high density surface dislocation is prepared. • The dislocation density could be precisely adjusted by controlling the etching time. • Electrode exhibits high HER activity and stability, shows self-optimized performance. • Dislocations have lower hydrogen adsorption free energies than perfect crystals. [ABSTRACT FROM AUTHOR]

We prepare undoped Mn 1.5 Co 1 Ni 0.5 O 4 and Cu and Sc co-doped Mn 1.5 Co 1 Ni 0.25 Cu x Sc 0.25−x O 4 (x = 0.05, 0.1, 0.15) films on Al 2 O 3 substrate by chemical solution deposition method. The crystallinity, surface morphologies, electrical transport property, optical property, and 1/ f noise property of these films are characterized. It shows that the Mn 1.5 Co 1 Ni 0.25 Cu 0.15 Sc 0.1 O 4 film possesses excellent electrical transport, optical and 1/ f noise properties compared with the other films. The absolute temperature coefficient of resistance and characteristic temperature of the Mn 1.5 Co 1 Ni 0.25 Cu 0.15 Sc 0.1 O 4 film are higher than that of Mn 1.5 Co 1 Ni 0.5 O 4 film, while its resistivity of 250 Ω·cm at 295 K is half of that Mn 1.5 Co 1 Ni 0.5 O 4 film. The transmittance and reflectance spectra of the films are measured and analyzed in the range of 0.55–2.0 µm, all the films show similar absorption structures in the measured spectrum. The 1/ f noise of the co-doped Mn 1.5 Co 1 Ni 0.5 O 4 films decreases significantly. The (γ/n)0.5/| TCR | value of the Mn 1.5 Co 1 Ni 0.25 Cu 0.15 Sc 0.1 O 4 reaches 2.3 × 10−12 cm1.5 K/% at 295 K, which is two orders lower than that of Mn 1.5 Co 1 Ni 0.5 O 4 film. Our results discover a thermosensitive material with excellent performance, which is expected to be applied to high performance uncooled infrared detectors. • We did a complete and systematic study for the Cu and Sc co-dopants effects on the electrical transport, optical, and low-frequency noise properties of Mn 1.5 Co 1 Ni 0.5 O 4 (MCN) thin films. • Mn 1.5 Co 1 Ni 0.25 Cu 0.15 Sc 0.1 O 4 thin film was found to be excellent electrical transport, optical and low-frequency noise performance, and we investigated and discussed the mechanisms of enhanced performance of the Cu and Sc co-doped MCN films. • The optical and low-frequency noise properties of Cu and Sc Co-doped MCN films were studied for the first time. • This study provides an insight to understand the effects of Cu and Sc co-dopants on Mn 1.5 Co 1 Ni 0.5 O 4 thin films, which has great significance for preparing high-performance uncooled infrared detectors based on MCN films. [ABSTRACT FROM AUTHOR]

• Single nickel atom is in-situ oxidized and embedded into Ru matrix. • NiRu-0.2 SAC exhibits a low overpotential of 17 mV @ 10 mA cm−2 which is much superior to that of commercial Pt/C (42 mV @ 10 mA cm−2) in alkaline media. • The introduction of oxidized single nickel atom creates a unique atomical interface which boosts water dissociation and H evolution during HER progress. [Display omitted] It is desirable but challenging to fine adjust the electronic structure of single atom to enhance the activity of single atom catalysts (SACs). Herein, we embedded an oxidized single nickel atom into pure ruthenium (Ru) metal (NiRu SAC), thereby constructing an atomic-level interface with high catalytic activity. NiRu SAC exhibits a long-term durability and an extremely low overpotential for hydrogen evolution reaction (optimal value reaches 17 mV) at 10 mA cm−2 which is superior to that of the commercial Pt/C catalyst and most reported Ru-based catalysts. NiRu-0.2 SAC also shows a remarkable oxygen evolution reaction (OER) performance of 210 mV at 10 mA cm−2, and a resulted excellent water splitting property (1.5 V vs. RHE @ 10 mA cm−2). Density functional theory (DFT) calculations demonstrate the fabricated oxidized single-nickel-atomic interface (between single nickel atom and neighboring Ru/O atom) not only lowers the energy barrier for water dissociation but also optimizes the H adsorption through the interaction between the interfacial Ru and O atoms. The single-atomic tailoring provides a new idea to further enhance the performance of single atom catalysts to satisfy the industrial applications. [ABSTRACT FROM AUTHOR]

Novel carbon quantum dots/1D MoO 3-x hybrid junction (noted as CQDs/MoO 3-x) was obtained by a facile hydrothermal route. The CQDs/MoO 3-x photocatalyst was estimated as an effective photocatalyst for inactivating E. coli and S. aureus under LED light. Compared with pure MoO 3 and MoO 3-x , CQDs/MoO 3-x photocatalyst displayed better performance in inactivating E. coli and S. aureus. The results of UV–visible diffuse reflectance spectrum (UV–vis DRS), transmission electron microscopy (TEM) and electrochemical impedance spectrum (EIS) indicated the enhanced photoactivity is ascribed to: (1) MoO 3-x has good absorption property of visible light; (2) the 1D structure of MoO 3-x prolongs the lifetime of photo-excited charge carriers; (3) CQDs modifying 1D MoO 3-x is not only favorable for absorption of visible light, but also for the fast transport and surface separation of the charge carriers. The capture experiment showed that holes (h+) are main active species in the photocatalytic process. This work presents an efficient photocatalyst for water antibacterial treatment. • Novel carbon quantum dots/1D MoO 3-x photocatalyst was successfully prepared. • The hybrid catalyst can inactivate E.coli and S. aureus under LED light. • Holes are main active species in the photocatalytic processing. • CQDs and 1D MoO 3-x are both favorable for the improved photocatalytic activity. [ABSTRACT FROM AUTHOR]

A novel β-Bi 2 O 3 @BiOBr core/shell photocatalyst was successfully designed by a facile ultrasonication method. The β-Bi 2 O 3 @BiOBr photocatalyst showed better photocatalytic antibacterial activity than pure β-Bi 2 O 3 and BiOBr under LED light. β-Bi 2 O 3 @BiOBr photocatalyst can completely inactivate Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) within 50 min. The enhanced photoactivity is due to a hybrid structure of BiOBr and β-Bi 2 O 3 , which led to an efficient separation of electron (e−) and hole (h+) pairs between the semiconductors. Moreover, the trapping experiment confirmed that h+ played an important role in the photocatalytic process. The present work provided a novel LED light-activated photocatalyst that was promising for water treatment. • Novel β-Bi 2 O 3 @BiOBr core/shell composite was prepared by a facile ultrasonic route. • β-Bi 2 O 3 @BiOBr can effectively inactivate E.coli and S. aureus under LED light. • Holes are main active species in the photocatalytic processing. • Dual charge transfer mechanism was proposed for photocatalytic process. [ABSTRACT FROM AUTHOR]