查看更多>>摘要：? 2022 Elsevier B.V.Carbon/Aluminum (C/Al) composites are receiving great attentions because they can present both good mechanical and electrical performance while keeping lightweight. However, the non-wettability of carbon and aluminum as well as the avoidable formation of the brittle phase Al4C3 can lead to a weak adhesion interface, limiting the performance improvement of the composites. In this work, an interlayer of silicon carbide and aluminum-silicon alloy the silicon was constructed at the interfaces of carbon matrix and aluminum, in order to resolve the bottleneck problem of composites performance improvement. Results indicated that the wettability of carbon matrix and aluminum melt was significantly improved by the constructed interlayer, and the contact angle decreased from 91° to 41°. Optimized parameters for the formation of moderate interlayer were also systematically examined. The interface of C/Al composites was changed from C/Al4C3/Al to C/SiC/Al-Si, resulting in the improvement of compressive strength, flexural strength and electrical conductivity from 212.75 MPa, 94.95 MPa, 2.25 × 105 S/m to 362.24 MPa, 144.42 MPa, 4.03 × 105 S/m, respectively, far better than the requirement of industrial standard. Mechanisms for the performance enhancement are also discussed.
查看更多>>摘要：? 2022 Elsevier B.V.Absorption spectra of Tb3Ga5O12 and Tb2(MoO4)3 are measured in temperature range from 4.2 to 300 K. Two low-energy lines appear above 20 K. This lines are ascribed to the vibronic-assisted optical absorption. Energy of the zero-point vibrations should be taken into account when optical data are used in calculation of the crystal electric field parameters.
查看更多>>摘要：? 2022 Elsevier B.V.Since the inception of white light-emitting diodes (white LEDs), phosphor-coated LEDs have been in focus owing to the tremendous advantageous that they offer in assorted applications ranging from biomedical to automotive applications, including plant growth. While, plant growth LEDs have been bustling the commercial market, there is ample scope to commercialize the promising far-red (FR) emitting LEDs for potential growth of plants in indoor farming. Herein, a facile and efficient strategy was used to develop Mn4+ (Nb site)- and Sm3+ (La site)- ions-doped Ca2LaNbO6 (CLNO:Mn4+/Sm3+) phosphors with outstanding photoluminescence (PL) properties. The PL properties of CLNO:Mn4+ and CLNO:Sm3+ phosphors showed FR emissions at 650 and 697 nm, respectively. When Mn4+/Sm3+ ions were co-doped in a CLNO host lattice, Rietveld refinement revealed alterations in bond lengths of the CLNO crystal structure, which enhanced the phosphor's thermal stability and photostability and caused the creation of effective pathways for efficient energy transfer from Sm3+ to Mn4+ ions. Furthermore, the reverse strategy, where the sensitizer (Sm3+) concentration was changed instead of activator (Mn4+) concentration, was used to achieve brilliant FR emission from the CLNO:Mn4+/Sm3+ phosphors and the dominant emission was perceived for the CLNO:0.2Mn4+/1.5Sm3+ phosphor. The internal quantum efficiency of the CLNO:0.2Mn4+/1.5Sm3+ phosphor was increased from 28% (CLNO:0.2Mn4+) to 56%. An LED fabricated by coating a CLNO:Mn4+/Sm3+ phosphor layer on a near-ultraviolet LED chip exhibited excellent FR emission with high color purity and with chromaticity coordinates of (0.733, 0.267). The results obtained for the CLNO:0.2Mn4+/1.5Sm3+ phosphor along with the characteristics of fabricated LED showed the high potential of the phosphor for use in promoting indoor plant growth.
查看更多>>摘要：? 2022 Elsevier B.V.A new type of low-melting-point heterogeneous alloy (LMH), based on Sn58Bi alloy (SBE), was prepared using Cu, Zn, Ag, and Sb microalloying and rapid solidification. The addition of Cu and Zn elements in equal mass ratios resulted in the Cu5Zn8 phase being dispersed in the Sn55Bi3Cu3Zn (LMH3) alloy. Subsequently, the additional Cu reacted with Sn to form a nano-sized η′-Cu6Sn5 phase at the interface of the Sn-Bi eutectic phase. Sn53Bi3Cu3Zn2Ag2Sb (LMH32) was prepared by adding appropriate amounts of Ag and Sb based on LMH3, leading to the precipitation of Ag3Sn and SbSn phases in the SBE matrix. The different precipitated phases in turn produced different types of fiber textures that existed in the matrix phase of SBE, LMH3, and LMH32. In addition, compared to LMH3, the presence of Ag3Sn and SbSn phases in LMH32 caused the formation of Bi twins identified via electron backscattered diffraction. The twin planes (101?1) and (11?02) had corresponding rotation axes and rotation angles of 93.8°[7?431] and 90.2°[5?415?], respectively. Nanoindentation results indicated that LMH32 exhibited higher creep resistance than Sn55Bi3Cu3Zn (LMH3) and SBE. The precipitated phase significantly refines the grain size and eutectic lath structure of the matrix phase (Sn and Bi). During the deformation process, the fine lath structure and the interfacial η′-Cu6Sn5 nanophase can hinder the slippage of the eutectic interface. Moreover, the presence of the precipitated phase forms a large strain gradient in the alloy matrix, which produces a significant back-stress hardening effect and induces substantial dislocation nucleation. The formation of more dislocations made the creep mechanism of LMHs depend on dislocation climbing.
查看更多>>摘要：? 2022 Elsevier B.V.High entropy alloy has attracted extensive attention due to the increased requirement for future high temperature structural superalloys. Quaternary Al-Cr-Fe-Ni alloys have been developed in recent years and have the potential to be employed as superalloy materials. How to improve the mechanical properties with strength and ductility balancing at room temperature and further improve the high temperature performance is an urgent problem to be solved. Thus, phase regulations were achieved by designing quaternary Al-Cr-Fe-Ni high-entropy alloys with different Al content to achieve excellent room temperature and high temperature mechanical properties to lay the foundation for its application. Here, a Co-free FeCrNiAl0.77 alloy (Al0.77 alloy) with low density and low cost was proposed and successfully manufactured by arc-melting. With the variation of Al element, the alloys were identified to be eutectic-like spinodal decomposition microstructures with dual BCC phase, consisting of the ordered B2 dendritic regions (enriched in Ni and Al), and disordered BCC inter-dendritic regions (enriched in Fe and Cr elements). The addition of Al can effectively decrease the density and slightly reduce the hardness. The Al0.77 alloy has a minimum density with 6.89 g/cm3 and a high hardness above 470 kgf/mm2. The light-weight alloys exhibit promising comprehensive mechanical properties by virtue to balance the strength and ductility, and have a compressive strength of above 3000 MPa and a compressive strain more than 44%. Furthermore, the Al0.77 alloy still remains high yield strength of 219 MPa at 900 ℃ with the volume fraction of B2 phase of 50.92% via the modulation of B2 phase. The quantitative strengthening mechanisms of Al0.77 alloy were presented, and the competitive strength increments of about 1148 MPa could be mainly attributed to the ordered and coherent microstructures and the nanosized precipitates embedded in the B2 phase regions. The proposed Al0.77 alloy with well balancing of specific strength and strain shows a great potential in the application in aerospace fields.
查看更多>>摘要：? 2022 Elsevier B.V.Praseodymium doped lutecia (Lu1?xPrx)2O3 (x = 0.003, 0.006 and 0.01) single crystals have been prepared by optical floating zone (OFZ) method. The concentration and temperature dependence of photoluminescence and scintillation properties, including photoluminescence excitation (PLE) and photoluminescence (PL), PL decay, X-ray excited luminescence (XEL) and afterglow curves were systematically investigated. Both onward (Pr(S6)→Pr(C2)) and inverse (Pr(C2)→Pr(S6)) energy transfers are observed in Lu2O3:Pr. It is found that with the increasing of Pr3+ concentration, the Pr(S6)→Pr(C2) energy transfers efficiency increases. And the PL decay time becomes faster due to the increasing cross relaxation transition. Meanwhile, as the temperature increases (78–500 K), the onward and inverse energy transfer efficiencies between the two kinds of Pr3+ are enhanced simultaneously. The highest scintillation efficiency is Lu2O3:0.6%Pr and afterglow levels of obtained single crystals were comparable.
查看更多>>摘要：? 2022 Elsevier B.V.The corrosion resistance of Al-Co-Cr-Fe-Ni high entropy alloys (HEAs) is probably affected by B2 phases. In this paper, the effect of B2 phases on the corrosion behavior of Al0.3CoCrFeNi HEAs in 3.5 wt% NaCl solution is clarified in this paper by purposely controlling the formation of B2 phases using annealing treatment. The microstructure characterization reveals that the content of (Al, Ni)-rich and Cr-poor B2 phases increases and the electrochemical measurements show that the pitting corrosion resistance is deteriorated as the annealing temperature decreases. Accordingly, the B2 phase is confirmed to be detrimental to the corrosion resistance of Al0.3CoCrFeNi HEAs. It can be attributed to the preferential dissolution of B2 phases causing easier pit initiation, which is evidenced by the corrosion morphology observation and scanning Kelvin probe force microscopy measurements, and to the slower repassivation rate leading to easier pit propagation, as demonstrated by the quantitative analysis of potentiostatic polarization curves.
查看更多>>摘要：? 2022 Elsevier B.V.Producing dielectric ceramics with favorable energy storage density, efficiency, and thermal stability has become an urgent task for developing energy storage devices. In this work, the innovative Pb-free (1-x)Bi0.85Sm0.15FeO3-xCa0.5Sr0.5Ti0.9Zr0.1O3 [(1-x)BSF-xCSTZ, x = 0.0, 0.1, 0.2, 0.3 and 0.4] ceramics were fabricated via traditional solid phase sintering approach. Their structures, electrical characteristics, and energy storage properties were researched comprehensively. The results verified that all the samples form solid solutions with pseudo-cubic perovskites structure. The density of ceramic samples is improved accompanied by gradually refined grain size upon increasing the CSTZ doping content. Interestingly, an excellent recoverable density of ～3.3 J/cm3 with high efficiency of ～78% is received at x = 0.3 under the average breakdown electric field of 350 kV/cm. The energy storage performances remained stable in a broad temperature range of 20 – 110 ℃, a large frequency range of 1 Hz – 1 kHz, and beyond 105 repeated charging-discharging cycles. The enhanced energy storage performances of BSF ceramics by introducing CSTZ result from the improved relaxor behavior and the increased electric breakdown strength. Our strategy for relaxor modulation with a sealed sintering method to achieve high energy storage performance can be valuable in BiFeO3-based ceramic capacitors.
查看更多>>摘要：? 2022 Elsevier B.V.Heterogeneous photo-Fenton technology combines photocatalytic and Fenton reactions to utilize solar energy and H2O2 efficiently, which is currently one of the most effective technologies for removing organic pollutants. In this work, FeWO4/BiOCl composite with different BiOCl contents was successfully produced by a two-step hydrothermal method. The photo-Fenton efficiency of the synthesized materials was assessed by the degradation of tetracycline hydrochloride (TCH) under simulated solar irradiation. The as-synthesized FeWO4/BiOCl composite exhibited significantly higher photocatalytic performances than individual semiconductors in the presence of H2O2 under simulated solar irradiation, and the apparent reaction rate constant reached as high as 0.0531 min?1, which was 4 times and 1.5 times higher than that of BiOCl and FeWO4, respectively. The effects of pH, TCH concentration, H2O2 concentration, and catalyst dosage on TCH degradation were investigated to identify the optimized reaction conditions. The excellent recyclability of FeWO4/BiOCl composite towards TCH photo-Fenton degradation was also shown. Photoelectrochemical analysis was performed to check the effective charge separation. The remarkably enhanced photo-Fenton catalytic performance of FeWO4/BiOCl composite was ascribed to effective charge separation and the production of more ·OH radicals. The FeWO4/BiOCl composite has proven to be a highly efficient and promising catalyst for Fenton-like processes to deal with practical environmental issues.
查看更多>>摘要：? 2022 Elsevier B.V.Although the power conversion efficiency of organo-halide perovskite solar cells (PSCs) has reached up to 25.5%, they face challenges to their commercialization due to the lack of stability against moisture, light, and heat. In this work, the durability of the PSC is improved using an efficient interfacial layer that simultaneously protects the perovskite layer against moisture and UV light/heat. The interfacial layer consists of hydrophobic two-dimensional perovskite (2D-PEA2PbI4) and azobenzene phase change material (PCM). The PCM acts as the UV light protector that can efficiently absorb UV light through its isomerization from cis to trans isomer. Remarkably, adding this dual-function interfacial layer prolongs the lifetime of the devices, particularly under one sun illumination and humid atmosphere (65–80% relative humidity). Also, the solid-solid PCM enhances the PCE of devices with 2D-perovskite by the specific orientation of 2D-perovskite between the 3D-perovskite grains. The stability of the modified device has been enhanced almost ten times as compared with the reference device.
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