查看更多>>摘要：Traditional inorganic ceramic materials usually exhibit macroscopic rigidity due to the incompatibility to the flexibility mechanism of traditional flexible materials such as sliding of polymer chains or atoms. Recently, new form of nanotechnology has been proposed to be capable of preparing inorganic flexible materials. In this paper, inorganic luminescent material (Ba,Ca)TiO3:Pr3+ was prepared into the flexible form by electrospinning technology, and the macroscopic flexibility of pure inorganic (Ba,Ca)TiO3:Pr3+ was systematic investigated. The crystal grain size was found to grow after higher temperature calcination, which benefits luminescence. However, lowering the calcination temperature will further optimize the flexibility of the membrane. This study shows that fibrous membrane fabrication is an applicable flexible fabrication strategy for inorganic oxides, which provides an important reference for the design of flexible materials. (C)& nbsp;2022 Published by Elsevier B.V.
查看更多>>摘要：In this study, trivalent dysprosium (Dy3+) activators were doped into barium tellurooxyphosphate Ba2TeP2O9 (BTP) by a solid-state sintering procedure, where alkali metal (A = Li, Na, and K) ions co-doped as charge compensator were aimed at improving the luminescent performance. To investigate optical absorption behavior, the electronic structure of the BTP host was realized via the density functional theory (DFT) method. The BTP:Dy3+ phosphor excited by 349 nm shows bright yellow emission. When the concentration of the Dy3+ activator is greater than 0.03 mol, concentration quenching occurs owing to dipole-dipole interaction. After doping 0.03 mol A+ ions into the BTP:0.03Dy3+ phosphor, the emission intensity of BTP:0.03Dy3(+)enhances by 1.18 (Li+), 1.43 (Na+), and 2.32 times (K+). Additionally, the BTP:0.03Dy3+,0.03 K+ phosphor exhibits satisfactory thermal stability. A white light-emitting diode (w-LED) was successfully fabricated from the BTP:0.03Dy3+,0.03 K+ and commercial blue phosphors with a 365 nm LED chip. The study reveals that the BTP:0.03Dy3+,0.03 K+ phosphor is a prospective yellow-emitting candidate for w-LED.(C) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：Glass containing magnetic nanocrystals are attractive to provide high optical linear and nonlinearity properties. In this study, we reported the synthesis of perovskite La0.8Sr0.2FeO3 nanocrystals in heavy metal oxide glass under the AlO3 tailoring. The influence of AlO3 amount to the formation of La(0.8)Sr(0.2)FeO(3 & nbsp;)nanocrystals and the influence of nanocrystals to glass structure, optical linear & nonlinear properties were thoroughly investigated. The 10 nm-nanocrystals of orthogonal La0.8Sr0.2FeO3 were synthesized by melting quenching followed with subsequent crystallization process at 400 ? for 30 min under the tuning of AlO3. The formed La0.8Sr0.2FeO3 were well distributed in matrix without aggregation. Structure and chemical valence study revealed the aluminum abnormality effect and the Sr2+ induced multi-valence states of Fe ions and oxygen vacancies in La0.8Sr0.2FeO3 lattice. Such modification clearly influenced the optical ab-sorption, refractive index, polarizability, energy band gap shrinkage and nonlinearity. Physical parameters such as oxygen packing density, free volume etc. were calculated to confirm the influence of AlO3 tailored La0.8Sr0.2FeO3 crystallization to glass. The glass with 10%AlO3 amount exhibited a large thermal stability (132 ?), low thermal expansion coefficient (10.2 x10(-6)/K) and high BO4/AlO4 units, providing suitable environment for La0.8Sr0.2FeO3 crystallization. About 20 nm nanocrystals were formed and well distributed in glass which contributed to large nonlinearity absorption coefficient (5.19 x10(-10) m/W) and FOM (13.6 x10(3 )esu cm) which much superior than from relative literatures. The obtained glass with extremely good optical linear and nonlinearity performances can be promising candidate for photonics device applications. (C) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：In this work, a gas atomized feedstock was used to fabricate an AlCoCrFeNi HEA coating using the high-velocity oxygen fuel (HVOF) process. The coating's resistance to room temperature surface degradation was evaluated using dry sliding wear and seawater corrosion testing. The coating retained the feedstock phase structure with negligible in-flight oxidation and was composed of a majority BCC phase with a minor B2 phase, resulting in a high micro-and nano-hardness of ~7 GPa. These observed phase compositions were consistent with thermodynamically calculated phase predictions using a CALPHAD model. Microstructure-mechanical property mapping revealed uniform microstructural characteristics. However, the multiscale wear resistance of the coating was critically affected by the presence of the hard BCC/B2 phase composition, which led to severe brittleness. Combinatorial assessment of the worn surface, wear debris and counter body indicated that wear was dictated by a combination of abrasive, surface fatigue, tribo-oxidation and adhesive wear. In addition, the coating exhibited superior general corrosion resistance compared with conventional SS316L, but the selective dissolution of the B2 phase preceded poor localized corrosion re-sistance, ultimately leading to pitting corrosion.(c) 2022 Published by Elsevier B.V.
查看更多>>摘要：Nickel and cobalt phosphates as a kind of low-cost inorganic materials are promising electroactive mate-rials. The structure stability and good dispersibility of micro-spherical materials make them popular in the energy storage field. Therefore, the fabrications of Ni-Co phosphate microspheres with some facile and cost-effective methods have attracted lots of attentions. In this work, we present one-step growth of Ni2Co (PO4)(2 )microspheres using urea as pH regulator. Urea decomposes into NH3 and CO2 during the hydro-thermal reaction process, resulting in the precipitation of Ni-Co phosphates. The as-prepared Ni2Co (PO4)(2) microspheres exhibit uniform and well-dispersed spherical morphology. Compared with traditional Ni2Co (PO4)(2 & nbsp;) particles, Ni2Co (PO4)(2) microspheres exhibit larger electrochemical specific surface area and smaller resistance of electrons/ions transfer. The specific capacity of Ni2Co (PO4)(2 & nbsp;) microspheres reaches as high as 153 mAh g(-1 )at a current density of 1 A g(-1), which is 1.59 times higher than that of traditional Ni2Co (PO4)(2) particles. In addition, this facile one-step synthetic method can be applied to fabricate series of Ni-Co phosphates with different Ni/Co atomic ratios. This work provides a facile synthetic method of fabricating Ni-Co phosphate materials, which has potential applications in large-scale manufacture. (C)& nbsp;& nbsp;2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：The effect of temperature on the tensile behavior and deformation mechanisms in a single crystal super alloys CMSX-4 is addressed and deduced by transmission electron microscopy in the temperature range from room temperature to 1100 degrees C. It is found that the tensile yield strength reaches a peak at 800 degrees C. And then, the yield strength decreases with increasing temperature. At room temperature, anti-phase boundary shearing dominates the plastic deformation. From 800 degrees C to 850 degrees C, the plastic deformation mechanism is mainly controlled by stacking fault shearing. The Kear-Wilsdorf locks have also appeared. When the temperature reaches at 950 degrees C, dislocation loops with anti-phase boundary shearing of the xfffc; precipitates are presented. Above 950 degrees C, the plastic deformation mechanism is processed by the rafted structure of the precipitates by-passing, i.e., Orowan by-passing and dislocation climb. Finally, according to the experimental results, the variety of stacking faults with temperatures and the relationship between the yield strength and plastic deformation mechanism are discussed. (c) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：Wurtzite Zn1-xMgxO epilayers (x = 0, 0.26, 0.44, 0.49, 0.66) grown by the plasma-assisted molecular beam epitaxy on ScAlMgO4 substrate were characterized using the methods of optical spectroscopy: spectroscopic ellipsometry (SE), optical absorption (OA), and photoluminescence (PL). The complex dielectric function in the spectral range of 210-1690 nm, band gap width, exciton absorption and emission parameters, and film quality were studied and discussed. Individual characterization of samples was provided by combining SE and OA measurement results. The observed increase of the band gap up to 4.35 eV with the rise of the MgO content allowed the recommendation of the wurtzite Zn1-xMgxO epilayers as material for UV sensors. The origin of defects hampering the practical application of the materials was discussed.(C) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：In this work, Zn-1.5Cu-1.0Ag-xZr (x = 0, 0.1, 0.5, 1.0) alloys were used as raw materials to research the effects of Zr content and hot rolling on the microstructure and mechanical properties of the alloys. The results revealed that as-cast Zn-1.5Cu-1.0Ag alloy was composed of eta-Zn phase and (Ag, Cu) Zn4 phase. After Zr addition, Zn22Zr was precipitated in both as-cast and as-rolled Zn-1.5Cu-1.0Ag-xZr alloys, and a new phase of CuZn5 was observed in as-rolled Zn-1.5Cu-1.0Ag-xZr alloys, resulting in the second phase strengthening. It was demonstrated that the grain sizes of the as-rolled alloys were much smaller than those of as-cast alloys, while Zr had slight effects on the grain sizes. In addition, Zn-1.5Cu-1.0Ag-0.1Zr alloy has the best as cast and as-rolled mechanical properties, and the yield strength, ultimate tensile strength and elongation of above two alloys are 84.18 +/- 0.71 MPa, 117.79 +/- 0.52 MPa, 3.73 +/- 0.40% and 218.14 +/- 0.04 MPa, 244.83 +/- 0.57 MPa, 64.50 +/- 4.60%, respectively. Moreover, the strength and elongation of both as-cast and as-rolled Zn-1.5Cu-1.0Ag-xZr alloys increase initially and then decline with the increase of Zr content. (C)& nbsp;2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：3 vol% TiB2 nanoparticles were added to an Mg-4Al-1.5Si alloy through semi-solid stirring followed by ultrasonic vibration to refine coarse Mg2Si phases. The effect of the added TiB2 nanoparticles on the size and morphology of the Mg2Si phases as well as the mechanical properties of the magnesium alloy was investigated. The experimental results showed that under the synergistic action of ultrasonic vibration and heterogeneous nucleation of TiB2 nanoparticles, the primary Mg2Si phases were not only refined from coarse dendritic to fine blocky shape but also uniformly dispersed. The morphology of the eutectic Mg2Si phases was transformed from coarse Chinese scripts to fine short strips. The Vickers-hardness, ultimate tensile strength, and yield strength of the obtained composites were increased by 101.8%, 69.8%, and 10.6%, respectively, compared with the matrix alloy, and the elongation was enhanced from 3.2% to 9.2% especially. The fracture mode was transformed from brittle fracture of the untreated Mg alloy to ductile fracture of the composites, indicating that the TiB2 nanoparticles play an effective role in strengthening and toughening Mg-Al-Si alloys. (C) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：Spark plasma sintering (SPS) is a promising method for producing high performance Cu-W composite with high copper and low tungsten content, which has wide application space in some occasions. Cu-20 wt%W composite with uniformly distributed ultrafine tungsten particles has been successfully fabricated under different spark plasma sintering temperatures. This paper deals with the impact of spark plasma sintering temperature on structure and performance characteristics of the composite. The intrinsic relationship between sintering temperature, microstructure and properties was studied. The results showed that the optimum SPS sintering temperature of Cu-20 wt%W composite powders produced by spray drying method is 950 degrees C. When the sintering temperature was increased, the content of copper-liquid would be increased, which could not only accelerate the rearrangement of tungsten particles but fill the holes to improve the performance of Cu-20 wt%W composite. However, a much higher temperature may lead to the sintering between tungsten particles, coarse copper net and the existence of copper vapor, ultimately resulting in the inhomogeneous distribution of tungsten and copper phases and the downward trajectory of the performance of the composite. The sintering mechanism was investigated and concluded with a detailed discussion. (c) 2022 Published by Elsevier B.V.
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