International Journal of Applied Ceramic Technology
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2019
·Vol. 17
·期 2
·778-789
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IF 1.074
Weihua Chen,Jiancheng Tang,Xingwang Shi,Nan Ye,Zhihao Yue,Xinghao Lin
High-purity titanium aluminum carbide (Ti 3 AlC 2 ) powders were synthesized by a microwave sintering method using different titanium sources as raw materials. The prepared products were characterized by differential scanning calorimetry (DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The results indicated that the synthesized Ti 3 AlC 2 powders have high purity (97.5%) and even distribution of the grain size when using a 3TiH 2 /1.2Al/2C mixture as raw materials when the microwave sintering temperature and time were 1300°C and 30 minutes, respectively. The formation mechanism of the Ti 3 AlC 2 is described as proceeding via four stages. The solid-phase reaction between titanium and aluminum occurs below the melting point of aluminum and the main product is a Ti 3 Al phase, which is an observed intermediate compound for the formation of Ti 2 AlC and Ti 3 AlC 2 . Thus, this study provides a beneficial approach to low-temperature synthesis of high-purity Ti 3 AlC 2 materials.
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COMPOSITES SCIENCE AND TECHNOLOGY
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2019
·
IF 6.309
Zhongyang Wang,Kai Sun,Peitao Xie,Yao Liu,Qilin Gu,Runhua Fan
The insulator-conductor percolative composites have been mostly constructed to achieve high permittivity and negative permittivity. In this work, permittivity transition from positive to negative is investigated in acrylic polyurethane-aluminum (APu/Al) percolative composites at radio frequency. Both the high permittivity and negative permittivity are accompanied with low loss due to the self-passivated nature of aluminum . The reactance and ac conductivity are studied to explain the dielectric properties , which provides an essential insight into the universal principles of high permittivity and negative permittivity behaviors in percolative composites. Meanwhile, when the conductive filler content exceeds the percolation threshold, a derived formula of permittivity has been put forward on the basis of the existing theoretical framework of percolation theory. Resourceful dielectric properties of APu/Al percolative composites will make them as potential alternatives for capacitors and metamaterials.
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JOURNAL OF AOAC INTERNATIONAL
·
2019
·Vol. 98
·期 1
·225-229
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IF 1.201
Zhang Jing,Yong Xiaojing,Zhao Dongyan,Shi Qiuyi
The content of mononuclear Al (Ala%) changed with its determination time (ta) under different dosages of Ferron (7-iodo-8-hydroxyquinoline-5-sulfonic acid, [Ferron]), and the change of Ala% with [Ferron] at different ta was systematically investigated for the firsttime. Thus, the most appropriate ta was found with the optimal [Ferron]. Also, the judgment of the platform (flat or level portion) of the complete reaction on the absorption-time curve determined in the hydroxyl polyaluminum solution by Ferron timed spectrophotometry (Ferron assay) was first digitized. The time point (tb) of complete reaction between the medium polyaluminum (Alb)and Ferron reagent depended on the reaction extent, and time could not be used only to judge. Thus, the tb was accurately determined and reduced
to half of original, which improved the experiment efficiency significantly. The Ferron assay was completely optimized.
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CHEMICAL ENGINEERING JOURNAL
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2019
·
IF 8.355
Handong Jiao,Shuqiang Jiao,Shijie Li,Wei-Li Song,Haosen Chen,Jiguo Tu,Mingyong Wang,Donghua Tian,Daining Fang
Although rechargeable Al batteries attract interests due to their features of abundant Al source and high safety, the Al negative electrodes suffer from critical problems, including dendrite, corrosion, pulverization, non-recyclable Al wastes, etc. For addressing these challenges, here a novel liquid gallium is demonstrated for negative electrodes of Al batteries. The results show that the liquid gallium negative electrode enables the reversible alloying/dealloying between Al and Ga. Remarkably, the essential problems in the solid Al negative electrodes, including dendrite, corrosion and pulverization, would be well avoided attributed to the liquid state of the Ga electrode during cycling. In addition to the enhanced stable cycling performance, Ga negative electrode is also recyclable, allowing the cycled Ga for further presenting stable cycling in the re-assembled batteries, and which is helpful for its practical application. The results in the present work open a precedent way to develop the advanced negative electrode with dendrite-free, corrosion resistant and recyclable features and advantages for various types of rechargeable batteries.
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Catalysts
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2019
·Vol. 9
·期 11
·944
·
IF 3.444
Jun Zhou,Yue Zhang,Song Li,Jing Chen
Heterogeneous catalysis often involves charge transfer between adsorbed molecules and the surface of catalyst, and thus their activity depends on the surface charge density. The efficiency of charge transfer could be optimized by adjusting the concentration of oxygen vacancies (Ov). In this work, hexagonal Ni(OH)2nanoparticles were initially synthesized by a hydrothermal process using aluminum powder as the sacrificial agent, and were then converted into 2D Ni/NiO nanocomposites through in situ reduction in hydrogen flow. The oxygen vacancy concentration in the NiO nanosheet could be well-controlled by adjusting the reduction temperature. This resulted in strikingly high activities for hydrogenation of nitrophenol. The Ni/NiO nanocomposite could easily be recovered by a magnetic field for reuse. The present finding is beneficial for producing better hydrogenation catalysts and paves the way for the design of highly efficient catalysts.Keywords:metal-oxide interaction;oxygen vacancy;hydrogenation;catalyst
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POWDER METALLURGY
·
2019
·
IF 1.149
Jiaxin Li,Yuhong Chen,Yongquan Li,Zhangjun Bai,Kang Wang
Alloys with composition of Ta-10 wt.% W and Ta-10 wt.% W-6 wt.% Al, respectively, were prepared by the hot-press sintering process. The oxidation behaviour at 900°C and 1000°C was studied. The oxidation weight gain curves of the Ta–10%W alloy followed the linear law and the final oxidation product was Ta2O5 solid solution. Meanwhile, due to the addition of Al, the oxidation weight gain curves of the Ta–10%W–6%Al alloy followed the parabolic law. The final oxidation products at 900°C formed a dense outer layer Al2O3 and an inner layer. However, after being oxidised at 1000°C, the oxidation products included Al2O3, AlTaO4 and Ta22W4O67. Since the dense Al2O3 oxide film was consumed by the generation of AlTaO4, the inward diffusion of oxygen cannot be prevented. The oxidation resistance degraded at 1000°C. The addition of Al significantly improved the oxidation resistance of the Ta-W-based alloy system.
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Materials
·
2019
·Vol. 12
·期 19
·3097
·
IF 2.972
Hailiang Du,Ning Tan,Li Fan,Jiajie Zhuang,Zhichao Qiu,Yanhua Lei
The diffusion coatings were deposited on commercially pure Ti and Ti-6Al-4V alloy at up to 1000 °C for up to 10 h using the pack cementation method. The pack powders consisted of 4 wt% Al (Al reservoir) and 4 wt% NH4Cl (activator) which were balanced with Al2O3(inert filler). The growth kinetics of coatings were gravimetrically measured by a high precision balance. The aluminised specimens were characterised by means of scanning electron microscopy (SEM), energy dispersive spectrometer (EDS) and X-ray diffraction (XRD). At the early stages of deposition, a TiO2(rutile) scale, other than aluminide coating, was developed on both materials at <900 °C. As the experimental temperature arose above 900 °C, the rutile layer became unstable and reduced to the low oxidation state of Ti oxides. When the temperature increased to 1000 °C, the TiO2scale dissociated almost completely and the aluminide coating began to develop. After a triple-layered coating was generated, the coating growth was governed by the outward migration of Ti species from the substrates and obeyed the parabolic law. The coating formed consisted of an outer layer of Al3Ti, a mid-layer of Al2Ti and an inner layer of AlTi. The outer layer of Al3Ti dominated the thickness of the aluminide coating.Keywords:diffusion coating;aluminide;pack cementation;Ti;Ti-6Al-4V;mechanism
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Nature Communications
·
2022
·Vol. 13
·期 1
·1-16
·
IF 17.694
Meng Yun,Chen Lijie,Chen Yang,Shi Jieyun,Zhang Zheng,Wang Yiwen,Wu Fan,Jiang Xingwu,Yang Wei,Zhang Li,Wang Chaochao,Meng Xianfu,Wu Yelin,Bu Wenbo
Bacteria and excessive inflammation are two main factors causing non-healing wounds. However, current studies have mainly focused on the inhibition of bacteria survival for wound healing while ignoring the excessive inflammation induced by dead bacteria-released lipopolysaccharide (LPS) or peptidoglycan (PGN). Herein, a boron-trapping strategy has been proposed to prevent both infection and excessive inflammation by synthesizing a class of reactive metal boride nanoparticles (MB NPs). Our results show that the MB NPs are gradually hydrolyzed to generate boron dihydroxy groups and metal cations while generating a local alkaline microenvironment. This microenvironment greatly enhances boron dihydroxy groups to trap LPS or PGN through an esterification reaction, which not only enhances metal cation-induced bacterial death but also inhibits dead bacteria-induced excessive inflammation both in vitro and in vivo, finally accelerating wound healing. Taken together, this boron-trapping strategy provides an approach to the treatment of bacterial infection and the accompanying inflammation.
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Journal of the American Chemical Society
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2022
·
IF 16.383
Ling Luo,Linan Wang,Jianbang Chen,Jiazheng Zhou,Zhihua Yang,Shilie Pan,Junjie Li
Large second-harmonic generation (SHG) response and broad band gap are two important and competitive parameters. It is difficult to balance them out in one material. In this work, by coupling alkali earth metal (AEM) octahedra with large highest occupied molecular orbital (HOMO)–lowest unoccupied molecular orbital (LUMO) gap and nonlinear optical (NLO)-active tetrahedra units, nine noncentrosymmetric (NCS) compounds, belonging to a new quaternary chalcogenide family AIB3IIC3IIIQ8VI with unique windmill-like [Mg3M3IIIQ24] (MIII = Al, Ga; Q = S, Se) units constructed by alternated [MgQ6] octahedra and [MIIIQ4] tetrahedra, are rationally designed and fabricated. The compounds show a stable structural framework but adjustable optical properties. Among them, NaMg3Ga3Se8 shows a large SHG response (∼1 × AgGaS2 (AGS)), wide band gap (in selenide) (2.77 eV), high laser-induced damage threshold (LIDT) (∼2.3 × AGS), and suitable birefringence (0.079@546 nm). It should be a potential candidate for infrared (IR) nonlinear optical (NLO) materials. The results enrich the chemical diversity of chalcogenides and open an avenue for the development of new IR NLO materials through the octahedra and tetrahedra coupled strategy.
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Small
·
2022
·Vol. 18
·期 50
·2204875
·
IF 15.153
Zhenbang Li,Fei Tian,Yan Li,Danni Lei,Chengxin Wang
The insertion type materials are the most important anode materials for lithium-ion batteries, but their insufficient capacity is the bottleneck of practical application. Here, LiAl 5 O 8 nanowires with high theoretical capacity and Li-ions diffusion coefficient are prepared and studied as an insertion anode material, which exhibits zero-strain properties upon electrochemical cycling. However, the poor electronic conductivity of LiAl 5 O 8 definitely sacrifices the capacity and limits the rate performance. Therefore, compact LiAl 5 O 8 and carbon composite are further synthesized, in which nanosized LiAl 5 O 8 particles are uniformly embedded in an amorphous carbon matrix. It displays a reversible capacity of 490.9 mAh g −1 at 1 A g −1 , and the capacity rises continuously to 996.8 mAh g −1 after 1000 cycles due to the interfacial storage mechanism, that the excess Li + ions can be accommodated in the grain boundaries and C/LiAl 5 O 8 interfaces.
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Journal of Materials Research and Technology-JMR&T
·
2023
·
IF 6.4
Bo Dong,Chengji Deng,Jun Ding,Hongxi Zhu,Qian Wang,Yong Zhang,Chao Yu
In this investigation, we have employed a novel approach to fabricate β–Sialon/Ti(C, N) composites through the nitridation treatment of Ti 3 SiC 2 powder. At temperatures ranging from 1373 to 1773 K, the reaction process was subjected to a comprehensive analysis to explore the transformation of phase and microstructure. The findings unequivocally highlight the influence of α–Al 2 O 3 presence and the high specific surface area of Ti 3 SiC 2 powder, resulting in distinctive phase and structural evolutions post nitridation, distinctly different from those observed in bulk Ti 3 SiC 2 . The β–Sialon/Ti(C, N) composites produced via this innovative method exhibit uniform local chemical composition and meticulous regulation of grain morphology. Moreover, the synthesis mechanism of β–Sialon/Ti(C, N) composites under nitrogen ambiance was thoroughly discussed. This straightforward approach has the potential for extensive–scale synthesis of β–Sialon/Ti(C, N) composites, offering promising avenues for their application in developing high–performance refractories or structural ceramics tailored to withstand severe high–temperature environments.
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JOURNAL OF ALLOYS AND COMPOUNDS
·
2023
·
IF 6.2
Jiaqi Wang,Xin Ding,Tongtong Gao,Huiling Zheng,Xuejiao Wang,Qiushi Wang,Cailong Liu
Due to the characteristics of non-contact, high sensitivity and spatial resolution, nanoscale optical thermometry is necessary in many applications such as micro/nano electronics, integrated optics and biomedicine. Herein, we report the synthesis of Nd 3+ /Yb 3+ co-doped AlN (AlN:Nd 3+ /Yb 3+ ) nanorods using an arc discharge method and investigate their phase, composition and morphology using XRD, Raman, XPS, EDS, ICP, SEM and TEM. The nanorods with rectangular cross-section are highly single crystalline and have a uniform smooth surface. Upon excitation at 980 nm, AlN:Nd 3+ /Yb 3+ nanorods exhibit up-conversion (UC) visible emission bands (around 544, 595 and 667 nm) and near-infrared emission bands (around 755 and 806 nm), which correspond to intra-4f electron transitions of the Nd 3+ ions. Later, the temperature dependence of UC luminescence behavior was systemically studied using luminescence intensity ratio (LIR) technique. It was verified that LIRs with non-thermally coupled levels ( 4 G 7/2 / 4 F 5/2 or 4 G 7/2 / 4 F 7/2 ) are suitable for temperature sensing. The maximum relative sensitivity based on 4 G 7/2 / 4 F 7/2 is 4.63% K −1 at 298 K, which is one of the highest values reported for optical thermometers. This work provides an efficient method for synthesizing wide-band gap semiconductors with doped size-mismatched functional atoms that can be used for high-sensitivity optical thermometry.
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