查看更多>>摘要：? 2022 Elsevier B.V.Lanthanide-doped core-shell upconversion particles with tunable emission bands and intensities in response to external stimuli provide opportunities for multicolor barcoding, optical imaging, and temperature sensing applications. Here, we provide a universal template that can be used as a basic medium for color control and temperature sensing. In a representative nanostructure, i.e., NaYF4:Yb/Er@NaYF4:Yb/Tm, two excitation-emission spectra-orthogonal luminescence groups with naked-eye observable emission colors (cyan or yellow-green) were obtained by switching the excitation wavelength (980 and 1550 nm). Furthermore, the temperature-responsive optical performance of the nanostructure was investigated, and enhanced temperature sensitivities Sa (0.2339 K?1) and Sr (2.5286% K?1) were achieved based on 3F2,3/4S3/2 non-thermally coupled energy levels (NTCLs). The photophysical properties of the nanostructure show great potential for anticounterfeiting and non-contact temperature sensing applications.
查看更多>>摘要：? 2022 Elsevier B.V.Interface modification of indium tin oxide (ITO) is a hot research topic to obtain highly efficient and stable organic light-emitting diodes (OLEDs), and the key point is to improve the hole injection efficiency between the electrode and organic layer. In this study, we demonstrate an optimization strategy based on the use of 3-aminobenzeneboronic acid (3ABBA) for modifying ITO at the anode interface. The protonation reaction of boronic acid groups with oxides and hydroxyl groups forms a self-assembled monolayer (SAM). Since the ionization potential (IP) of 3ABBA-SAM is 5.44 eV, the hole injection barrier at the interface is minimized. Compared with a control device using PEDOT:PSS, the synergistic effects of the optimized 3ABBA-SAM significantly improves the maximum power efficiency (PEmax of 8.52 lm W?1) and maximum current efficiency (CEmax of 10.45 cd A?1) of the device, and the turn-on voltage is reduced by 0.2 V. In addition, effective interface modification reduces the hydrophilicity of the device and provides support for the stability of the OLED in the ambient environment. Therefore, we believe that a simple 3ABBA-SAM interface modification project can promote the development of high-performance and low-cost OLEDs.
查看更多>>摘要：? 2022 Elsevier B.V.In order to improve corrosion resistance of stainless steels, a CoCrNiMoBC coating was prepared by laser cladding. The microstructure, composition, and crystallographic orientation relationships of the coating were discussed. Electrochemical methods were used to evaluate its corrosion behavior. Results showed that the coating had remarkable resistance to chloride ion corrosion under strongly acidic conditions. The critical pitting temperature of the coating was higher than 80 °C in both neutral and acidic chloride ion environments. Immersion tests confirmed that pits did not expand significantly after 10 days immersion in 5 M HCl solution. The excellent corrosion resistance stemmed from a stable passivation film formed due to the synergistic effects of composition and microstructure.
查看更多>>摘要：? 2022 Elsevier B.V.In this study the preparation, characterization, and photoluminescence properties of the Eu3+-doped apatite compounds have been presented. The Eu3+ ion doped silicate-substituted apatite, Ca9.9Eu0.1(PO4)2(SiO4)4(OH)2?xFx where x = 0; 0.8; 1.2; 2.0, was obtained by a microwave-assisted hydrothermal method. A detailed investigation on the heat-treated samples was done by using X-ray diffraction (XRD), scanning electron microscopy energy-dispersive spectrometry (SEM-EDS), transmission electron microscopy (TEM) and Fourier-transform infrared spectroscopy (FT-IR). The luminescence behavior of Eu3+ ion was explored based on excitation and emission spectra as well as luminescence decay profiles. The emission spectra under excitation to the charge-transfer (CT) transition shows the broad band associated with Eu2+ ion emission. The asymmetry parameter (R parameter) and CIE color coordinates were also discussed.
查看更多>>摘要：? 2022 Elsevier B.V.Ceramics with composition of Pr2(Zr1?xTix)3(MoO4)9 (0.02 ≤ x ≤ 0.10) were fabricated by classic solid-phase method. X-ray diffractometer (XRD), Scanning electron microscope (SEM), Raman spectra, FT-IR spectrometer and Agilent vector network analyzer were used to investigate the composition of phase, microscopy, lattice vibration, internal dielectric responding and dielectric properties, respectively. XRD indicates the Pr2(Zr1?xTix)3(MoO4)9 (0.02 ≤ x ≤ 0.10) ceramics own trigonal-type crystal structure and R-3c space group and the SEM patterns confirms the optimal sintering temperature is 800 °C. Simultaneously, the ceramic reached the optimal microwave dielectric properties with εr = 10.8, Q×f = 81,539 GHz and τf = ?14.2 ppm/°C at 800 °C for x = 0.10. By means of the theory of complex crystals chemical bonds (P-V-L theory), the connections with crystal structure and microwave dielectric properties were deeply discussed. Due to the relatively low fired temperature and superior dielectric properties, there is an expect for Pr2(Zr0.90Ti0.10)3(MoO4)9 ceramic to apply in low temperature cofired ceramic (LTCC).
查看更多>>摘要：? 2022 Elsevier B.V.The microstructure evolution, mechanical response and deformation mechanism of the extruded Mg-2.5Nd-0.5Zn-0.5Zr alloy sheet by high-temperature (423–573 K) tensile were investigated. The results showed that the alloy exhibited excellent high-temperature mechanical properties at 523 K (extrusion direction (ED): ultimate tensile strength (UTS)~191.5 MPa, yield strength (YS)~154.5 MPa, elongation (EL)~30.1%; transverse direction (TD): UTS~190.5 MPa, YS~148.2 MPa, EL~35.2%). The YS of ED and TD of the alloy decreased linearly, and the anisotropy of the alloy decreased gradually (from 0.9261 to 1.009) with the increase of tensile temperature, which was beneficial to the subsequent processing of the alloy. Moreover, the decreased anisotropy was the result of grain size, second phase particles size and texture state. The microstructure showed obvious deformed structures at 423 K and it was gradually replaced by dynamic recrystallization with an average grain size of 3.3–4.2 μm and the texture strength weakened greatly (maximum pole density value reduced from 15.8 to 4.0) as the temperature increased to 573 K. Meanwhile, both the deformation models and the contributions of different deformation mechanisms at different tensile temperatures were roughly estimated. It was found that basal slip was always the main deformation mechanism at different tensile temperatures, but its contribution to deformation decreased with increased tensile temperatures (from 93.0% to 66.6%). With the increase of tensile temperature, the degree of prismatic slip (from 4.1% to 23.2%) and pyramidal slip (from 2.9% to 10.2%) in deformation gradually increased.
查看更多>>摘要：? 2022 Elsevier B.V.In this study, Inconel 718 (IN718) alloy was manufactured by selective laser melting (SLM), and the effects of solution and double aging treatments (SDA) on the microstructure and mechanical properties of the IN718 alloy were investigated. Results revealed that the increase of the solution temperature promotes the increase of the number of recrystallized grains of the IN718 alloy. When the solution temperature is 940 ℃, a large amount of needle-like γ″ are formed. With the increase of the solution temperature (980 ℃–1140 ℃), the needle-like γ″ phase in the alloy begins to decrease and gradually disappear, accompanying the precipitation of the nanoscale granular γ'/γ" composite phase. When the solution temperature is 1140 ℃, an enhanced ultimate tensile strength (UTS) of 1451 MPa and a slight sacrifice of fracture elongation (23.7%) are achieved for the IN718 alloy. The formed nanoscale granular γ'/γ" composite phase and annealing twins were responsible for the enhanced mechanical properties of the IN718 alloys.
查看更多>>摘要：? 2022 Elsevier B.V.Ex-situ and quasi in-situ thermal exposure experiments have been conducted to explore the coarsening behavior of γ′ phases in the Ni-Al binary model single crystal superalloy at 1000 °C. It is obtained in ex-situ experiments that the number density and volume fraction of γ′ phases decrease with the exposure time increasing, while the average size increases. The coarsening of γ′ phases in the width direction obeys the cubic law described by the LSW theory, while the average size change in length is much greater than that in width. In quasi in-situ experiments, it is observed that small γ′ phases shrink or dissolute, the large ones tend to grow up. The coalescence of γ′ phases is also observed, which induces a sharp increase in the length direction.
查看更多>>摘要：? 2022 Elsevier B.V.In a catalytic reaction involving nanoparticles, the particle size is an important factor influencing the reactivity. In this research, small PdCu alloy nanoparticles with an average size of 2.7 nm were easily synthesized by the co-reduction of Pd and Cu precursors using potassium bromide (KBr) as a capping agent to achieve size control in an aqueous phase. When the synthesized 2.7 nm-sized PdCu alloy nanoparticles were applied as an electrocatalyst for CO2 reduction reaction (CO2RR), using a gas diffusion electrode system, Faradaic efficiency (FE) of over 80% for CO with a significantly low H2 selectivity (≤2% FE) at 100 mA/cm2 was achieved. The results revealed that the synthesized nanoparticles are highly suitable for CO2-to-CO conversion at high current densities.
查看更多>>摘要：? 2022 Elsevier B.V.Due to the sluggishness of oxygen reduction reaction (ORR), the industrialization of fuel cells (FCs) is hindered by the expensive and scarce platinum metal in the cathode. The exploration of low-cost, stable and efficient Pt-free catalysts becomes particularly urgent. Composite catalysts formed by WS2 which makes it attachment to two carbon substrates were synthesized by hydrothermal method. The results of the morphology and composition characterization for two composite catalysts predict their excellent ORR activity. Electrochemical researches have confirmed this prediction. WS2/activated carbon (AC) and WS2/reduced graphene oxide (rGO) demonstrate excellent electrocatalytic performance with onset potential of 0.96 V and 0.90 V (vs. RHE) and durability with the attenuation of only 3.6% and 4.4% of the initial current after 8 h of continuous operation. ORR occurring on WS2/AC and WS2/rGO demonstrates a typical 4-electron pathway. The present research provides a feasible strategy for expanding novel, low-cost, effective, and stable ORR catalysts as alternative catalysts for Pt/C.
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