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High-entropy Sm_(2)B_(2)O_(7)(B=Ti,Zr,Sn,Hf,Y,Yb,Nb,and ta) oxides with highly disordered B-site cations for ultralow thermal conductivity

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Journal of Materials Science & Technology 2022年第24期119卷 182-189页

作者： Liang Xu lei Su Hongjie Wang Hongfei gao Pengfei guo Min Niu Kang Peng lei Zhuang Zhiwei Dai State Key Laboratory for Mechanical Behavior of Materials Xi’an Jiaotong UniversityXi’an 710049China

Materials with ultralow thermal conductivity and good thermal stability are of great interest in numerous applications such as energy storage and conversion devices,and thermal insulation *** this work,a family of high-entropy Sm_(2)B_(2)O_(7)(B=Ti,Zr,Sn,Hf,Y,Yb,Nb,and ta) oxides with highly disordered cations on the B-site has been synthesized by introducing large atomic-size mismatch,mass and charge *** tuning the composition,the high-entropy Sm_(2)B_(2)O_(7) oxides can be engineered from pyrochlore to fluorite structure,accompanied with an order-disorder *** pyrochlore Sm_(2)(Nb_(0.2)Sn_(0.2)Ti_(0.2)Y_(0.2)Zr_(0.2))_(2)O_(7) and fluorite Sm_(2)(Nb_(0.2)ta_(0.2)Y_(0.2)Yb_(0.2)Zr_(0.2))_(2)O_(7) exhibit low thermal conductivities of 1.35 W·m^(-1)·K^(-1) and 1.23 W·m^(-1)·K^(-1),respectively,indicating their good thermal *** addition,the high-entropy fluorite Sm_(2)(Nb_(0.2)ta_(0.2)Y_(0.2)Yb_(0.2)Zr_(0.2))_(2)O_(7) also shows average thermal expansion coefficient of 10.2 × 10^(-6)℃^(-1) and high-temperature stability even after thermal exposure at 1600 °C in air for 30 *** results indicate that the high-entropy Sm_(2)B_(2)O_(7)(B=Ti,Zr,Sn,Hf,Y,Yb,Nb,and ta) can be promising candidates for thermal barrier coatings and thermally insulators.

关键词： High-entropy oxides Atomic sizes mismatch Mass and charge disorder Thermal conductivity Thermal barrier coatings materials

2D/2D covalent organic framework/CdS Z-scheme heterojunction for enhanced photocatalytic H_(2) evolution:Insights into interfacial charge transfer mechanism

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Journal of Materials Science & Technology 2023年第6期137卷 223-231页

作者： Ruiqi gao Junxian Bai Rongchen Shen lei Hao Can Huang lei Wang guijie Liang Peng Zhang Xin Li Institute of Biomass Engineering Key Laboratory of Energy Plants Resource and UtilizationMinistry of Agriculture and Rural AffairsSouth China Agricultural UniversityGuangzhou 510642China Hubei Key Laboratory of Low Dimensional Optoelectronic Materials and Devices Hubei University of Arts and ScienceXiangyang 441053China State Centre for International Cooperation on Designer Low-Carbon and Environmental Materials(CDLCEM) School of Materials Science and EngineeringZhengzhou UniversityZhengzhou 450001China

Covalent organic frameworks(COFs)with high crystallinity and flexible designability have been consid-ered as promising candidates for photocatalytic hydrogen ***,the existence of unpropi-tious exciton effects in COFs leads to poor charge separation,and thus results in low photocatalytic ***,to improve the photoelectron migration efficiency,we designed a 2D/2D organic/inorganic direct Z-scheme COF-based heterojunction(TptaP/CdS),by the in-situ growing of CdS nanosheets on the COF copolymerized via 2,4,6-tris(4-aminophenyl)-1,3,5-triazine(taP)and 1,3,5-triformylphloroglucinol(Tp).The femtosecond transient absorption(fs-ta)decay kinetics of TptaP-COF and TptaP/CdS further reveal the processes of shallow electron trapping and the recombination of the free photogenerated electron-hole *** particular,the transient absorption traces for TptaP-COF and TptaP/CdS normal-ized to the photoinduced absorption peak can effectively verify the Z-scheme charge transfer between TptaP-COF and CdS,which could enhance the charge mobility and separation,thus reducing the pho-tocorrosion of ***,ultraviolet photoelectron spectroscopy(UPS),in-situ X-ray photoelec-tron spectroscopy(XPS),transient photovoltage measurements,and electron spin resonance(ESR)spec-troscopy further confirm the establishment of the internal electric field(IEF).This work demonstrates the important role of COFs in the construction of 2D/2D organic/inorganic direct Z-scheme heterojunctions and offers a new avenue to explain the criticality of dynamics of the photogenerated carriers for the construction of Z-scheme heterojunctions.

关键词： Femtosecond transient absorption Photocatalytic hydrogen evolution Covalent organic frameworks(COFs) Direct Z-scheme heterojunction CdS

Kinetics and thermal stability of the Ni_(62)Nb_(38–x)ta_x(x=5, 10, 15,20 and 25) bulk metallic glasses

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Science China(Physics,Mechanics & Astronomy) 2017年第7期60卷 70-75页

作者： MengKe He Yi Zhang lei Xia Peng Yu College of Physics and Electronic Engineering Chongqing Normal University School of Communication & Information Engineering University of Electronic Science and Technology of China

We studied thermal stability and its relationship to the glass-forming ability （gFA） of the Ni62Nb38-xtax （x=5, 10, 15, 20, 25） bulk metallic glasses （BMg） fi＇om a kinetic point of view. By fitting the heating-rate dependence of glass transition temperature （Tgonsct） and crystallization temperatures （Txonset and Txpcak） of the Ni62Nb38_xtax BMg using the Vogel-Fulcher-tammann （VFT） equation, we obtained the ideal glass transition and crystallization temperatures （Tg0 and Tx2） and the fragility parameter （m）, and also constructed continuous heating transition （CHT） diagrams for crystallization of the BMg. The CHT diagrams of the BMg indicate enhanced thermal stability by ta addition; the Tg~ as well as the Tx~ also illustrates this improved stability limit. The compositional dependence of m, which agrees well with that of the reduced glass-transition temperature, indicates a strong correlation between liquid fragility and glass-forming ability in the present alloy system. These results provide new evidence for understanding thermal stability, liquid fragility, and gFA in BMg.

关键词： bulk metallic glasses thermal stability kinetics glass-forming ability

tannic acid and silicate-functionalized polyvinyl alcohol-hyaluronic acid hydrogel for infected diabetic wound healing

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Regenerative Biomaterials 2024年第4期3卷 125-137页

作者： Zhentian Diao Longkang Li Huan Zhou lei Yang School of Materials Science and Engineering Hebei University of TechnologyTianjin 300131China Center for Health Science and Engineering Hebei Key Laboratory of Biomaterials and Smart TheranosticsSchool of Health Sciences and Biomedical EngineeringHebei University of TechnologyTianjin 300131China

Healing of chronic diabetic wounds is challenging due to complications of severe inflammatory microenvironment,bacterial infection and poor vascular ***,a novel injectable polyvinyl alcohol-hyaluronic acid-based composite hydrogel was developed,with tannic acid(ta)and silicate functionalization to fabricate an‘all-in-one’hydrogel *** one hand,after being locally injected into the wound site,the hydrogel underwent a gradual sol-gel transition in situ,forming an adhesive and protective dressing for the *** of rheological characteristics,mechanical properties and swelling ability of PTKH could be performed via regulating ta and silicate content in *** the other hand,PTKH was capable of eliminating reactive oxygen species overexpression,combating infection and generating a cell-favored microenvironment for wound healing acceleration in *** animal studies demonstrated that PTKH could greatly stimulate angiogenesis and epithelization,accompanied with inflammation and infection risk ***,in consideration of its impressive in vitro and in vivo outcomes,this‘all-in-one’multifunctional hydrogel may hold promise for chronic diabetic wound treatment.

关键词： diabetic wound healing ROS overexpression combating infection stimulate angiogenesis

Transient features of graphitization and nitrogen-vacancy color centers in a diamond fabricated by localization femtosecond laser direct writing

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Science China(Technological Sciences) 2024年第8期67卷 2530-2536页

作者： CUI Lin YIN SiYu HU ZiFan WANg lei State Key Laboratory of Integrated Optoelectronics College of Electronic Science and EngineeringJilin UniversityChangchun 130012China

Femtosecond laser direct writing provides an efficient approach to fabricating single nitrogen vacancy(NV) color centers with a relatively high yield. Different from previously reported NV color centers with a random distribution in a bulk diamond or nanocrystals, this gives an opportunity to study the photophysical properties of single NV color centers with precise numbers and positions. However, ultrafast studies on single NV color centers prepared by localization femtosecond laser direct writing are still rare, especially for the graphitization inside a diamond and its relationship with single NV color centers. Here, we report the broadband transient absorption(ta) spectroscopic features of the graphitization and NV color centers in a diamond fabricated by localization femtosecond laser direct writing at room temperature under 400 nm excitation. In comparison with the graphene oxide film, the bleaching features of the graphitization point array in a diamond are similar to reduced graphene oxide,accompanied by excited state absorption signals from local carbon atom vacancy defects in graphene-like structures induced by laser writing. On the other hand, transient features of laser processing array containing single NV color centers with a yield of~50% are different from those of the graphitization point array. Our findings suggest that for ultrashort pulse processing of diamonds, broadband ta spectral signals are sensitive to the surrounding atomic environment of processing sites, which could be applied to laser writing point defects in other materials used as solid-state single photon sources.

关键词： nitrogen-vacancy color center graphitization diamond femtosecond laser direct writing ultrafast spectroscopy

A Retrieval Algorithm of Sheet Metal Parts Based on Relationships of Features

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Chinese Journal of Aeronautics 2012年第3期25卷 453-472页

作者： WANg Dawei YAN guangrong lei Yi ZHANg Jiaying School of Mechanical Engineering and Automation Beihang University Beijing 100191. China Modern Education Center. Shandong University of Science and Technology. ta ian 271019. China

With the rapid increase in the number of three-dimensional （3D） models each year, to quickly and easily find the part desired has become a big challenge of enterprises. Meanwhile, many methods and algorithms have been proposed for part retrieval. However, most of the existing methods are designed lbr mechanical parts, and can not be well worked for sheet metal part re- trieval. An approach to feature-based retrieval of sheet metal parts is presented. Firstly, the features frequently used in sheet metal part design are chosen as the ＂＇key words＂ in retrieval. Based on those features, a relative position model is built to express the different relationships of the features in 3D space. Secondly, a description method of the model is studied. With the descrip- tion method the relative position of features in sheet metal parts can be expressed by four location description matrices. Thirdly, based on the relative position model and location description matrices, the equivalent definition of relationships of two feature groups is given which is the basis to calculate the similarity of two sheet metal parts. Next, the tbrmula of retrieval algorithm for sheet metal parts is given. Finally, a prototype system is developed to test and verify the effectiveness of the retrieval method suggested. Experiments verify that the new method is able to meet the requirements of searching sheet metal parts and possesses potentials in practical application.

关键词： CAD sheet metal retrieval algorithm features search 3D model

Toward developing Ti alloys with high fatigue crack growth resistance by additive manufacturing

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Journal of Materials Science & Technology 2023年第1期132卷 166-178页

作者： F.Wang L.M.lei X.Fu L.Shi X.M.Luo Z.M.Song g.P.Zhang Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China AECC Commercial Aircraft Engine Co. Ltd.Shanghai 201306China

Fatigue crack growth behaviors were investigated by three-point bending tests for ta19 alloy fabricated by laser metal deposition and four kinds of heat-treated *** crack growth resistance of the ta19 samples in the near-threshold regime and Paris regime was evaluated through the experimental characterization and theoretical analysis of the interaction between fatigue crack andα/βphase inter-face,columnar prior-βgrain boundary and colony *** results show that in the near-threshold regime,the fatigue crack propagation threshold and resistance increase with the increase of widths of lamellarαp phases and colonies,and the decrease of the number ofαlaths with an angle(ϕ)relative to the applied stress direction ranging from 75°to 90°.In the Paris regime,the fatigue cracking path can be deflected at colony boundaries or columnar prior-βgrain *** larger the deflection angle,the more tortuous the cracking path and the lower the fatigue crack growth *** angle(γ)of the columnar prior-βgrain growth direction relative to the build direction affects not onlyϕof differentαvariants,but also the fatigue cracking path deflection angle(θij)at columnar prior-βgrain *** optimal combination ofγ=0°-15°-0°-15°for several adjacent columnar prior-βgrains is derived from the theoretical analysis,and that can effectively avoidϕbeing in the range from 75°to 90°and makeθij as large as *** findings provide a guide for the selection of scanning strategies and process parameters to additively manufacture Ti alloys with high fatigue damage tolerance.

关键词： Ti alloy Fatigue crack growth Additive manufacturing Phase interface grain boundary

Least-Squares Solution with the Minimum-Norm for the Matrix Equation A^TXB+B^TX^ta = D and Its Applications

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Acta Mathematicae Applicatae Sinica 2007年第2期23卷 269-280页

作者： An-ping Liao Yuan lei Xi-yan Hu Coilege of Mathematics and Econometrics Hunan University Changsha 410082 China Department of Mathematics and Information Sciences Changsha University Changsha 410003 China

An efficient method based on the projection theorem, the generalized singular value decomposition and the canonical correlation decomposition is presented to find the least-squares solution with the minimum-norm for the matrix equation A^TXB＋B^TX^ta = D. Analytical solution to the matrix equation is also derived. Furthermore, we apply this result to determine the least-squares symmetric and sub-antisymmetric solution of the matrix equation C^TXC = D with minimum-norm. Finally, some numerical results are reported to support the theories established in this paper.

关键词： Matrix equation minimum-norm solution generalized singular value decomposition canonical correlation decomposition

Microstructure,Properties,and grain growth Kinetics of Mo-5ta Refractory Sputtering ta.gets Prepared by SPS

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Journal of Wuhan University of Technology(Materials Science) 2023年第6期38卷 1248-1254页

作者： LIU Dawei YANg Xiaolong HUANg lei PAN Yafei ZHANg Jiuxing School of Materials Science and Engineering Hefei University of TechnologyHefei 230009China Engineering Research Center of High-Performance Copper Alloy Materials and Processing Ministry of EducationHefei University of TechnologyHefei 230009China

Mo-5ta ta.gets were prepared by the spark plasma sintering(SPS)technology under the sintering temperatures of 1400-1600℃,the holding times of 0-20 min,and the axial pressure of 30 *** microstructure,performance,and grain growth kinetics of Mo-5ta sputtering ta.gets were *** the increase of sintering temperatures and times,ta can more dissolve in Mo and form a Mo(ta)solid *** grain sizes of Mo-5ta ta.gets remain unchanged at low temperatures(1400-1500℃)while increasing significantly at high temperature(1600℃)with the extension of the holding *** addition,the densities and Vickers hardness(HV_(0.5))first ascend and then decrease with sintering *** thermal conductivity is positively correlated with the grain size and density,as a result of their joint *** on the comprehensive analysis,the grain growth is dominated by the combination of boundary diffusion and volume *** n=2,the activation energies of grain growth under holding times of 5,10,20 min are calculated as 762.70,617.86,and 616.52 kJ/mol,respectively.

关键词： SPS Mo-5ta ta.gets structure properties grain growth kinetics