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Precipitation behavior of selective laser melted FeCoCrNiC0.05 high entropy alloy
摘要： Interstitial elements are e?ective to strengthen high entropy alloys (HEAs). In this work, FeCoCrNiC0.05 was prepared by selective laser melting (SLM) followed by annealing. The e?ects of annealing on the microstructures and mechanical properties of the SLMed FeCoCrNiC0.05 were investigated. Results show that, nano-scale Cr23C6-type carbides can precipitate under annealing conditions, leading to higher yielding strength. The SLMed FeCoCrNiC0.05 annealed at 1073 K for 0.5 h has a yielding strength of 787 MPa and an elongation of 10.3%. Precipitation kinetics in SLMed FeCoCrNiC0.05 has been established according to Avrami formula. The high strength can be attributed to solid solution hardening, precipitation hardening and cell-like structures.
关键词： Precipitation kinetics,Hardening mechanism,Selective laser melting,Mechanical properties,High entropy alloy
更新于2025-11-14 17:04:02
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Double-layered hierarchical titanate and its attaching and splitting mechanism
摘要： Double-layered hierarchical titania materials exhibit outstanding properties. However, most hydrothermal synthesis methods of bilayer hierarchical titania materials are time-consuming and high alkali-consuming. In this study, a less alkali-consuming one-pot method was developed to synthesize bilayer hierarchical titanate, specifically, 1D nanoarray layer and 3D hierarchical layer. Morphologies of the composites can be manipulated by varying hydrothermal conditions and introducing titanate nuclei based on the attachment rule and splitting mechanism. More importantly, splitting phenomena were observed and confirmed in both nanosheet-to-nanowire transformation process and nanowire-to-nanotube transformation process. It was firstly confirmed that the driving force of the splitting process is the transformation from amorphous state titanate to crystalline state titanate.
关键词： 1D nanostructures,Splitting mechanism,Hierarchical titanate,Attaching mechanism
更新于2025-11-14 17:03:37
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Cu/Sb Codoping for Tuning Carrier Concentration and Thermoelectric Performance of GeTe-Based Alloys with Ultralow Lattice Thermal Conductivity
摘要： Pristine GeTe shows promising thermoelectric performance but is limited by the high carrier concentration (nH) from Ge vacancies and thermal conductivity. Herein, Cu/Sb was chosen as codopants to suppress the high nH and to decrease thermal conductivity. In this condition, a promising zT of ～1.62 under 773 K was acquired in the Ge0.85Te(CuSb)0.075 system proposed in this paper/work. Results show that as the dopant concentration increases, the power factor rises due to the reduction of the nH to ～1 × 1020 cm?3. Apart from this, the total thermal conductivity also declines from ～7.4 W m?1 K?1 to ～1.59 W m?1 K?1 originating from an ultralow lattice thermal conductivity, in which the multiscatter mechanism from grain boundaries and point defect disperses the frequency phonons di?erently. The ?ndings in this paper combine thermal and electronic strategies and lay the foundation to develop Pb-free thermoelectric materials.
关键词： multiscatter mechanism,Cu/Sb codoped GeTe,thermoelectric materials,ultralow lattice thermal conductivity,zT value,carrier concentration,Seebeck coefficient
更新于2025-11-14 17:03:37
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Visible-light-driven g-C3N4/Cu2O heterostructures with efficient photocatalytic activities for tetracycline degradation and microbial inactivation
摘要： g-C3N4/Cu2O composites were successfully synthesized by a facile chemical precipitation method. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscope (FESEM), transmission electron microscopy (TEM) and UV diffuse reflectance spectroscopy (UV-DRS) techniques were employed to characterize the as-synthesized photocatalysts. The photocatalytic experiments indicated that the g-C3N4/Cu2O composites displayed higher photodegradation activity of tetracycline (TC) and inactivation efficiencies of Escherichia coli (E. coli) as well as Fusarium graminearum (F. graminearum) in comparsion with bare g-C3N4 and Cu2O under visible light irradiation. Photoluminescence (PL) spectra implied that the heterojunction between g-C3N4 and Cu2O could efficiently promote the separation efficiency of photo-induced charge carriers. Active species trapping experiment and electron spin resonance (ESR) analysis revealed that ?O2-, ?OH and h+ played important roles in the photocatalytic process. This study could provide new insights into the design of multifunctional g-C3N4-based photocatalysts for environmental purification.
关键词： inactivation mechanism,tetracycline,heterostructures,photocatalysis,g-C3N4/Cu2O
更新于2025-11-14 15:29:11
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Preparation of ellipsoidal rod-shaped silica nanocomposite abrasives by Chromium ion/PEG200 induced method for sapphire substrates chemical mechanical polishing
摘要： Abrasive is vital to sapphire substrates chemical mechanical polishing and provides the most critical support for ?attening of sapphire. This work proposed a method to prepare ellipsoidal rod-shaped silica nanocomposite abrasives in order to increase the material removal rate and improve the surface roughness, which were applied to chemical mechanical polishing on sapphire substrates. Ellipsoidal rod-shaped silica nanocomposite abrasives were prepared by Chromium ion/PEG200 induced method. In this work, the synthesis process of ellipsoidal rod-shaped silica nanocomposite abrasives was discussed. As an inducing agent, Chromium compounds were bonded with two SiO2 particles via chemical bonds. And ellipsoidal rod-shaped silica nanocomposite abrasives were coated by PEG200 via hydrogen bonds. Results from X-ray photoelectron spectroscopy and time-of-?ight secondary ion mass spectroscopy revealed the occurrence of solid-state chemical reactions. The contact angle tests indicated the polishing liquid containing ellipsoidal rod-shaped silica nanocomposite abrasives had a good wettability. Ellipsoidal rod-shaped silica nanocomposite abrasives showed an excellent chemical mechanical polishing performance with a higher material removal and a lower surface roughness due to an excellent combination of chemical effect and mechanical effect occurred between ellipsoidal rod-shaped silica nanocomposite abrasives and sapphire substrates. A material removal model was built to describe the polishing behavior of ellipsoidal rod-shaped silica nanocomposite abrasives.
关键词： Polishing mechanism,Sapphire substrates,Ellipsoidal rod-shaped silica nanocomposite abrasives,Chemical mechanical polishing
更新于2025-11-14 15:27:09
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MAPbI3/agarose photoactive composite for highly stable unencapsulated perovskite solar cells in humid environment
摘要： Perovskite solar cells, bearing the merits of facile preparaion and remarkable efficiency, has great potential for bringing the photovoltaic industry to a new generation. The photovoltaic market demands high-efficiency, high stability and low-cost fabrication of perovksite solar cells, especially stability to the humid environment for operation. Here, MAPbI3/agarose photoactive material for humid stable unencapsulated devices has been proposed. These solar cells have been operated in ambient humid environment without glove box, exhibiting efficiency up to 14.66% and retain 90% of its PCE after 1392 h and 60% of initial PCE after 1972 h in ambient humid environment (RH>70%) without encapsulation. FTIR and XPS measurements reveal two critical factors for the improved stability. The molecular level interactions between agarose and MAPbI3 passivates the grain boundaries of perovskite thus preventing its degradation. Moreover, the formation of Li+-agarose complex at the interface between perovskite layer and hole conductive layer, effectively prevents the water uptake of MAPbI3 layer. Both effects of passivation and minimization of hygroscopicity of LiTFSI by agarose lower the decomposition speed of perovskite, which obviously increases the power efficiency and stability of device.
关键词： humid stability mechanism,perovskite solar cells,MAPbI3/agarose photoactive composite
更新于2025-11-14 15:24:45
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Facile synthesis of yellow emissive carbon dots with high quantum yield and their application in construction of fluorescence-labeled shape memory nanocomposite
摘要： Synthesizing carbon dots (CDs) with efficient long-wavelength emissions (i.e., yellow- to red light) generally suffer from sophisticated approaches, time-consuming process, harsh conditions, and requirement of organic solvent; also, a further limitation of the resulting CDs is relatively low quantum yield (QY) in aqueous solution. Herein, novel yellow emitting CDs (Y-CDs) with a considerable QY of 62.8% were synthesized from a precursor comprising resorcinol and o-phenylenediamine via a facile microwave method. To probe the fluorescence mechanism, another typical resorcinol-derived CDs using ethylenediamine as dopant were fabricated as well, showing strong green emission with an absolute QY of 60.6%. Spectroscopic and structural characterizations indicated that the distinct redshift of green to yellow emission depended on the dimension of conjugated sp2-domain and the content of graphitic N heavily, while the excellent QY was highly related to the low proportion of defective sp2 carbon cluster and high nitrogen content within CDs. Moreover, the Y-CDs were confirmed to be capable of introducing additional crosslinking points in poly(vinyl alcohol) (PVA) polymer, which resulted in the Y-CDs-contained nanocomposite behaving superior and tunable water-induced shape recovery performances. Importantly, since being labeled with long-wavelength emission, the responsiveness of PVA/Y-CDs composite will contribute to its versatile utilization in biology-relevant fields.
关键词： shape recovery,fluorescence mechanism,yellow emission,carbon dots,nanocomposite
更新于2025-11-14 15:23:50
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A new disordered langbeinite-type compound, K <sub/>2</sub> Tb <sub/>1.5</sub> Ta <sub/>0.5</sub> P <sub/>3</sub> O <sub/>12</sub> , and Eu <sup>3+</sup> -doped multicolour light-emitting properties
摘要： For the first time, a new langbeinite-type phosphate, namely potassium terbium tantalum tris(phosphate), K2Tb1.5Ta0.5(PO4)3, has been prepared successfully using a high-temperature flux method and has been structurally characterized by single-crystal X-ray diffraction. The results show that its structure can be described as a three-dimensional open framework of [Tb1.5Ta0.5(PO4)3] interconnected by K+ ions. The TbIII and TaV cations in the structure are disordered and occupy the same crystallographic sites. The IR spectrum, the UV–Vis spectrum, the morphology and the Eu3+-activated photoluminescence spectroscopic properties were studied. A series of Eu3+-doped phosphors, i.e. K2Tb1.5–xTa0.5(PO4)3:xEu3+ (x = 0.01, 0.03, 0.05, 0.07, 0.10), were prepared via a solid-state reaction and the photoluminescence properties were studied. The results show that under near-UV excitation, the luminescence colour can be tuned from green through yellow to red by simply adjusting the Eu3+ concentration from 0 to 0.1, because of the efficient Tb3+→Eu3+ energy-transfer mechanism.
关键词： photoluminescence,Langbeinite-type phosphate,crystal structure,energy-transfer mechanism,multicolour light
更新于2025-11-14 15:23:50
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Selective H2S-sensing performance of Si nanowires through the formation of ZnO shells with Au functionalization
摘要： A novel gas sensor fabricated from ZnO-shelled Si nanowires (SiNWs) is presented. After coating a thin layer of Au on the surfaces of Si NWs, ZnO layers were formed on the surfaces of p-SiNWs by thermal evaporation of Zn powders and a subsequent oxidation process. Microscopic analysis confirmed the successful formation of ZnO-Si core-shell NWs with Au nanoparticles present on the shell surface. The gas sensing performance of the gas sensor fabricated using the p-Si/n-ZnO core-shell NWs was evaluated for various gases. The sensor exhibited outstanding response and selectivity to H2S gas. The gas sensing mechanism was evaluated in detail and attributed to various factors, including the formation of ZnO/Si and Au/ZnO heterojunctions and the chemical attraction between ZnO and Au. The results demonstrate a new sensing material for H2S detection in various fields that can be easily incorporated into Si-based devices.
关键词： Gas Sensor,Si Nanowires,ZnO,Sensing Mechanism,Shell,Au
更新于2025-11-14 15:15:56
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A reaction-based turn-on fluorescent sensor for the detection of Cu (II) with excellent sensitivity and selectivity: Synthesis, DFT calculations, kinetics and application in real water samples
摘要： A reaction-based turn-on fluorescent chemosensor RhB-Cu, starting from rhodamine B (RhB), for Cu2+ was easily synthesized in two steps. The sensor could selectively detect Cu2+ with a 100-fold fluorescence enhancement among the common metal ions, exhibiting an extremely low detection limit of 4.7 nM. To the best of our knowledge, this was the best record for the detection of Cu2+ with organic fluorescent sensors. There was a 1:1 binding stoichiometry between RhB-Cu and Cu2+ with an association constant of 6.42 × 104 M-1. Noteworthy, it could distinguish Cu2+ from Cu+, which was hard to realize in the previous studies. In addition, the detection mechanism was proposed based on mass spectrometric analysis and density functional theory (DFT) calculations. Kinetic studies were conducted to obtain the activation energy, enthalpy and entropy, so as to elucidate the solvent effect. Interestingly, the kinetic compensation effect (KCE) was uncovered in this work. Finally, RhB-Cu was proved to have the capability to work in real water samples. It would highly contribute to the even better design of fluorescent sensor for Cu2+ in future.
关键词： fluorescent sensor,solvent effect,kinetic compensation effect (KCE),copper,density functional theory (DFT),PET mechanism
更新于2025-10-22 19:38:57