查看更多>>摘要：Visible light photodetector is one of the rapidly growing fields in optoelectronics. We report investigation of photoelectrical properties of visible lateral photodetectors based on pure CdS, Mg or Al doped CdS and Mg+Al co-doped CdS thin ?lms prepared by the spray technique. The CdS phase purity was confirmed by X-ray diffraction and Raman studies. The morphological analysis shows spherical shaped grains in the pure CdS film. The nature of grains slightly changes from spherical to rod-like shape for the doped films, confirming the incorporation of doped ions into the host lattice. The prepared films exhibit bandgaps around 2.3 eV. The photodetector structures were illuminated by laser light with energy of 2.33 eV (532 nm). Under such an above-bandgap excitation, electron-hole pairs are created by the band-to-band absorption of photons, resulting in the enhancement of photocurrent. The fabricated photodetector is able to work at room temperature under very low excitation power density ranging 1–5 mW/cm2. The Al doped CdS photodetector at 5 V bias exhibits the highest photocurrent of 1.06 × 10?5 A, responsivity (R) of 2.13 A/W, detectivity (D*) of 5.23 × 1011 Jones and external quantum e?ciency (EQE) of 497.3% under 532 nm illumination.
查看更多>>摘要：Ni(OH)2 has been acknowledged as a promising oxygen evolution reaction (OER) electrocatalyst owing to its good electrochemical activity and low cost. However, application of the pristine Ni(OH)2 is limited by the poor conductivity and low exposure of the active sites. Herein, a hemin@Ni(OH)2 composite is prepared through a hydrothermal reaction. Heat treatment temperature proves to have a great influence on the electrocatalytic activity. In 0.1 M KOH electrolyte, the composite treated at 175 °C shows an overpotential of only 287 mV to reach the current density of 10 mA·cm?2. Besides, the low Tafel slope (42 mV·dec?1) and superior stability (15 h at 10 mA·cm?2) also confirm the composite as an excellent OER electrocatalyst. The brilliant activity and stability toward OER can be attributed to the promoted coupling between Ni and Fe centers and the improved conductivity due to the 2D 18 p-electrons ring conjugate structure of hemin. Besides, effective hydrogen bonds between Ni(OH)2 and hemin hinder the aggregation of Ni(OH)2, which ensures the catalyst enormous accessible active sites. This work offers a new method for the modification of Ni(OH)2 as OER electrocatalysts. And the application of hemin also serves as a successful case for the use of biomass materials in OER electrocatalysis.
查看更多>>摘要：Ti-6Al-4V (TC4) has been widely used in dentistry as an implant biomaterial but is faced with difficulties in forming parts by traditional processing methods. Directed energy deposition (DED), a promising additive manufacturing technology, is very suitable for developing TC4/ZrO2 composite with different proportions of nano-ceramic additions (0, 5 or 10 wt%). As the content of alloying element Zr increased, the grains were refined, and the lattice distortion was more severe due to solid solution, both of which caused Vickers hardness of the composite to increase from 308 to 485. The electrochemical tests and corrosion morphology analysis indicated that the corrosion was intensified with the decrease of pH and the increase of F? ion concentration. The corrosion product detection showed that ZrO2 oxide might reduce the compactness of the TC4 passive film containing TiO2 and Al2O3, which resulted in a slight decrease in corrosion resistance but still satisfied the clinical requirements. Cytotoxicity and cytoskeleton staining results demonstrated that the composite was beneficial to biological safety and biocompatibility.
查看更多>>摘要：High-power, high-brightness laser lighting technology put forward new requirements for the service stability of color conversion materials. Phosphor-in-glass materials (PiGs) have emerged with their unique advantages of withstanding high power excitation density. High luminous efficiency (LE) and high internal quantum efficiency (IQE) LuAG:Ce PiG is still an urgent demand for high power laser lighting conversion materials. In this paper, LuAG:Ce PiGs was successfully prepared by careful design of glass matrix composition. The maximum internal quantum efficiency of LuAG:Ce PiG is 93.8%. The conversion efficiency (CE) of LuAG:Ce PiG from blue to green light is increased to 56.3%. The luminous efficiency (LE) even reaches 225 lm W?1, which is the best performance of LuAG:Ce in LD lighting so far. These results show that this work has taken a big step in improving the performance of LuAG:Ce Green converter and will greatly promote the development of LD lighting.
查看更多>>摘要：In this work, the effect of the addition of Zirconium on the microstructure, hardness, wear behavior and magnetic properties of NiCoCrFe High Entropy Alloy (HEA) was investigated. The crystal structures and phase evolution of the alloys were characterized using X-Ray Diffraction (XRD). XRD patterns showed the FCC and BCC solid solutions in both alloy powders. To investigate the effect of Zr element on the wear behavior of NiCoCrFe HEA, the alloys, in the form of powder, were compressed using Spark Plasma Sintering (SPS) process, and then, the pin on disk wear test was applied. The results showed that after SPS, BCC/FCC phases of the NiCoCrFeZrx (x = 0) alloy had converted to single-phase FCC (NiCoCrFeZr0.4); however, the mechanical properties and wear behavior of the alloy improved compared to the NiCoCrFe alloy. The micro-hardness and nano-hardness of NiCoCrFe alloy increased from 682 ± 7 and 672 ± 7 Vickers to 828 ± 10 and 845 ± 10 Vickers, respectively. Moreover, the addition of Zr led to significant increasing in wear resistance and decreasing the coefficient of friction. Results of the scanning electron microscope (SEM) equipped with an XRD energy spectrometer (EDS) illustrated that the presence of Zr led to the conversion of the dominant abrasive mechanism to adhesive mechanism. Eventually, the results of the Vibrating Sample Magnetometer (VSM) indicated that the addition of Zr element led to the tendency of NiCoCrFe alloy to be paramagnetic. In this way, the magnetic saturation is reduced by 15%, and the coercive force is increased by 133%.
查看更多>>摘要：High Nb-TiAl alloys are important materials to realize critical, light-weight parts of high-temperature applications. It has been challenging, however, to realize their laser-based additive manufacturing (AM) due to the materials’ high crack sensitivity. To mitigate the cracking problem particularly relating to oxygen, this study is designed to investigate the impact of introduced rare earth element (Y) on the microstructure, surface chemistry, and laser absorptivity of gas-atomized Ti-45Al-8Nb powder, and consequently on the printability of the alloy regarding its selective laser melting (SLM). It is observed that the Y addition significantly improves the SLM printability of the alloy and realizes samples that are free of macrocracks. The change in the surface structure of the powder is regarded as a critical factor contributing to improved printability. The corresponding chemical state and layer thickness of the oxide film covering the powder are determined by X-ray photoelectron spectroscopy (XPS) depth profile and transmission electron microscopy (TEM). It is further found that the surface structure of the powder leads to a higher laser absorption. As suggested by the study, modification of powder chemistry and powder surface structure by rare earth elements can be an effective means to improve the SLM formability of crack-sensitive materials.
查看更多>>摘要：The temperature and amplitude dependences of internal friction Q?1 and shear modulus G for the Na0.875Li0.125NbO3 solid solution were studied in the temperature range of 300–700 K. It was found that the material undergoes two structural phase transitions near temperatures T1 ≈ 620 K and T2 ≈ 559 K. Both low-temperature phases are ferroelectric one, whereas the phase above the temperature T1 is paraelectric one. It is shown that the main contribution to mechanical losses below T1 is related to the motion of domain walls. The Q?1 maxima observed near temperatures T1 and T2 are satisfactory described within the framework of the low-frequency fluctuation mechanism of internal friction. The amplitude dependences of Q?1 are in agreement with the Friedel dislocation model.
查看更多>>摘要：The constricted visible light harvesting and undesirable rapid recombination of photogenerated e- and h+ set enormously hinder the activity of the photocatalysts. In this work, we design and develop two-dimensional/one-dimensional (2D/1D) S-g-C3N4/Co-NiS heterojunction with intimate heterointerface contact by self-assembly technique. The fast electron transportation of 2D S-g-C3N4 nanosheets (NSs) and the well-matched energy levels of bare S-g-C3N4 and 5% Co-NiS nanorods (NRs) cooperative support the transportation and separation of photo-carriers at the heterointerface of S-g-C3N4/Co-NiS. The as-fabricated samples were evaluated EDX, SEM, UV–vis, XRD, TEM, FTIR, XPS, BET, PL and transient photocurrent. Moreover, this well-defined construction boosts sunlight harvesting and exhibits a large surface area. Benefiting from the intimate coupling and structural features, the 20% S-g-C3N4/Co-NiS heterojunction attains a noteworthy photocatalytic methylene blue (MB) degradation rate of 100%, considerably improved than that of bare NiS (34%), 5% Co-NiS (57%) and pristine S-g-C3N4 (31%). Concurrently, the photocorrosion of bare S-g-C3N4 was suppressed by simultaneous integrating with NiS and engineering with cobalt, which was demonstrated through a chemical stability test with 6 consecutive experimental tests. Such outstanding enrichment in photocatalytic activity and chemical stability was primarily attributed to boosting spatial charge separation and synergistic effects of the 20% 2D/1D S-g-C3N4/Co-NiS nanocomposites (NCs). Antibacterial performance of 20% 2D/1D S-g-C3N4/Co-NiSNCs against 4 infectious species was evaluated in visible light radiance. Our results emphasize the great importance of the efficacious heterointerface blend of 2D/1D S-g-C3N4/Co-NiS NCs as a promising photocatalyst scheme for enhanced photocatalytic degradation of dye and disinfection of pathogens.
查看更多>>摘要：In this study, MoS2/TiO2 nanohybrids, formed through hydrothermal synthesis technique, was considered as a superior heterojunction for the removal of tetracycline (TC) and Pb (II) reduction under visible light irradiation. The Z-scheme MoS2/TiO2 nanohybrids was easily synthesized with much narrower nanoparticles, ~10 times the outstanding charge separation, and greater specific surface area than bulk MoS2 or TiO2. The MoS2/TiO2 nanohybrids achieved a stronger photocatalytic activity, which could degrade 94% TC within 60 min. The optimized nanohybrids catalysts demonstrated outstanding efficiency with the apparent reaction rate constants of 0.05 min?1 for TC removal, about 3–4 times as bigger as the removal rate of bulk components. Superoxide radical (˙O2?) was presumed as the conduct active species in the potential improvement mechanism of organized MoS2/TiO2 nanohybrids for photocatalytic activities was introduced. These can admit to prefer photodegradation pathways and mechanism of tetracycline by nanohybrids with visible light activity. The novel nanohybrids photocatalysts have great structural stability, greater light absorption, and superior cycle performance, which could be utilized as an efficient process of antibiotics degradation and Pb (II) removal.
查看更多>>摘要：A polycrystalline sample of the uranium ternary germanide UFe0.39Ge2 was examined by means of X-ray powder diffraction, DC magnetization and AC magnetic susceptibility, heat capacity and electrical resistivity measurements performed in wide ranges of temperature and magnetic fields. The experiments confirmed that the compound crystallizes with orthorhombic crystal structure of the CeNiSi2-type that is closely related to that of the ferromagnetic superconductor UGe2 and orders ferromagnetically at 37 K. Moreover, it exhibits some features characteristic of ferromagnetic cluster glasses. The electrical transport in UFe0.39Ge2 is strongly influenced by structural disorder arising from the partly occupied Fe-sites in its crystallographic unit cell.
NSTL
Elsevier