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Hard yet tough and self-lubricating(CuNiTiNbCr)C_(x) high-entropy nanocomposite films:Effects of carbon content on structure and properties

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Journal of materials Science & Technology 2024年第6期173卷 20-30页

作者： Y.T.Li x.m.chen x.K.Zeng m.Liu x.Jiang Y.x.Leng Key Laboratory of Advanced Technologies of materials Ministry of EducationSchool of Materials Science and EngineeringSouthwest Jiaotong UniversityChengdu 610031China Key Laboratory of Noise and Vibration Research Institute of AcousticsChinese Academy of SciencesBeijing 100190China State Key Laboratory of Acoustics Institute of AcousticsChinese Academy of SciencesBeijing 100190China School of mechanical and Electrical Engineering Mianyang Teachers’CollegeMianyang 621000China

The single-phase high-entropy alloy film is difficult to meet severe friction conditions due to its low hardness and high friction ***-composite structure film is composed of at least two separated phases,showing the properties of strength and toughness integration and excellent wear *** design of nanocomposite structures can effectively improve the mechanical properties and tribological properties of high-entropy alloy *** this study,the(CuNiTiNbCr)C_(x) nanocomposite high-entropy films(HEFs)integrated with high hardness,high toughness,and self-lubrication were synthesized by the double-target co-sputtering *** effect of carbon content on microstructure,mechanical properties,and tribological properties of(CuNiTiNbCr)C_(x) films was *** the increase of carbon content in the HEFs,the carbon atoms preferentially react with Ti,Nb,and Cr to form a(TiNbCr)C ceramic-reinforced phase,and then the excess carbon atoms precipitate in the form of amorphous carbon(a-C)lubricating phase in the *** structure of the HEFs changes from an amorphous structure to a nanocomposite structure of amorphous(amorphous CuNiTiNbCr phase+a-C phase)/nanocrystalline(TiN-bCr)C *** the carbon content is about 21.2 at.%,the carbide phase in the film reaches saturation and the hardness and modulus of the films are highest,which are 18 GPa and 228 GPa,*** HEFs with a carbon content of 44.0 at.%show the best toughness and tribological properties with a friction coefficient of 0.16 and a wear rate of 2.4×10^(-6) mm^(3)/(N m),which is mainly attributed to the excellent resistance to fatigue crack growth and the interfacial lubricating layer formed in the friction *** nanocomposite(CuNiTiNbCr)C_(x) HEFs show very promising application prospect in the field of friction protection.

关键词： High-entropy films Nanocomposite Double-target co-sputtering Strengthening-toughening Tribological properties

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Room-temperature ferroelectricity in A-site ordered Ruddlesden-Popper Li_(2)CaTa_(2)O_(7) ceramics

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Journal of materiomics 2020年第3期6卷 593-599页

作者： B.H.Zhang Z.Z.Hu B.H.chen x.Q.Liu x.m.chen Laboratory of Dielectric materials School of Materials Science and EngineeringZhejiang UniversityNo.38 Zheda RoadHangzhou310027China

In the present work,the crystal structure,ferroelectric and dielectric properties of the dense single-phase Li_(2)CaTa_(2)O_(7) ceramics with A-site ordered double-layer Ruddlesden-Popper structures have been investigated by the experiments and first-principles calculations.A polar Pna21 phase was determined by the Rietveld refinement against the x-ray diffraction pattern at room temperature,and it was confirmed by its lowest calculated energy and rigid phonon *** ferroelectricity was found by observing the ferroelectric hysteresis loop at room temperature,and its remanent polarization was similar to the value calculated from the Berry phase and Born effective charge *** ferroelectricity is a nonconventional proper one since its polarization is induced from the displacement of oxygen anions instead of tantalum cations based on the individual atomic polarization.A first-order transition from an antiferroelectric to paraelectric phase around 900 K was found by the DSC and variable-temperature dielectric *** the present work,the room-temperature ferroelectricity is experimental confirmed in the present ceramics,inspiring the search for new ferroelectricity in the ceramics with A-site ordered Ruddlesden-Popper structures.

关键词： Ferroelectricity A-site ordered ruddlesden-popper Dielectric response First-principles calculation

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First-order phase transition and unexpected rigid rotation mode in hybrid improper ferroelectric(La,Al)co-substituted Ca_(3)Ti_(2)O_(7) ceramics

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Journal of materiomics 2019年第4期5卷 618-625页

作者： Z.Z.Hu J.J.Lu B.H.chen T.T.Gao x.Q.Liu W.Wen x.m.chen Laboratory of Dielectric materials School of Materials Science and EngineeringZhejiang UniversityNo.38 Zheda RoadHangzhou310027China Shanghai Synchrotron Radiation Facility Shanghai Institute of Applied PhysicsChinese Academy of SciencePudong New AreaShanghai201204China

Ca_(3)Ti_(2)O_(7) with Ruddlesden-Popper structure exhibits the largest polarization among the known hybrid improper ***,the high Curie temperature impedes the thorough study of phase transition through dielectric *** to the previous theoretical design rule,the Curie temperature can be suppressed by increasing the tolerance ***,in the present work,high-quality Ca_(3-x)LaxTi_(2-x)Al_(x)O_(7)(x=0.0,0.1,0.2,0.3)ceramics with increased tolerance factors were successfully *** amplitude of oxygen octahedral tilt mode indeed decreases with increasing tolerance factors,leading to a degeneration of ferroelectric ***,the unexpected rigid rotation mode causes the composition-invariable coercive *** Curie temperatures decrease linearly with increasing x and tolerance *** variable-temperature dielectric constant confirms first-order improper ferroelectric transitions in Ca_(3)Ti_(2)O_(7)-based *** results of variable temperature xray diffraction reveal the coexistence of two-phases below Curie *** present work confidently confirms the first-order improper ferroelectric transition in Ca_(3)Ti_(2)O_(7)-based ceramics by combining results of variable-temperature dielectric response and in-situ x-ray powder diffraction.

关键词： Hybrid improper ferroelectricity Ca_(3)Ti_(2)O_(7) Rigid rotation mode First-order phase transition Dielectric response

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EFFECTS OF ORDERING DOmAIN STRUCTURE ON DIELECTRIC PROPERTIES OF DOUBLE PEROVSKITE La_(2)NimnO_(6)

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Journal of Advanced Dielectrics 2011年第3期1卷 319-324页

作者： Y.Q.LIN S.Y.WU x.m.chen Department of materials Science and Engineering Zhejiang University Hangzhou 310027 P.R.China

Two sets of La_(2)NimnO_(6)ceramics with different B-site ordering degree were prepared and *** valence states of Ni^(2+)and mn^(4+)were con-rmed,and the B-site ordering degree was estimated qualitatively using magnetic and Raman *** ordering of Ni^(2+)and mn^(4+)was the primary origin for the relaxor-like behavior of the present *** ordering degree of B-site ions greatly affected the dielectric properties,i.e.,more ordered sample indicated higher dielectric ***,the grain boundary layer capacitor(GBLC)effect was also activated but limited at the high temperatures and low frequencies.

关键词： Ordering degree La_(2)NimnO_(6)ceramics dielectric properties

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Enhanced ferroelectric and piezoelectric characteristics in Ca-substituted BaTi_(0.88)Zr_(0.12)O_(3)ceramics

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Journal of Advanced Dielectrics 2022年第3期12卷 58-64页

作者： S.B.chen S.Y.Wu x.m.chen School of materials Science and Engineering Zhejiang University 38 Zheda Road Hangzhou 310027P.R.China

In this work,Ba1−xCaxTi_(0.88)Zr_(0.12)O_(3)(x=0.00-0.25)ceramics were prepared by a solid-state reaction method,and the variation of dielectric,ferroelectric and piezoelectric characteristics has been investigated together with the structure *** crystal structure varies from rhombohedral to tetragonal at room-temperature and the morphotropic phase boundary(mPB)is determined around x=0.10,where the significantly enhanced ferroelectric and piezoelectric properties are *** the increase of Ca content,the system gradually evolves into a relaxor *** work provides useful guidance for future research on lead-free piezoelectric materials.

关键词： morphotropic phase boundary relaxor ferroelectric piezoelectric properties

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小麦条锈病小种抗性基因鉴定

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国外农学（麦类作物） 1993年第6期 14-16页

作者： x.m.chen 万安民

利用了8个北美的条锈菌小种.在北美小麦不同条锈病鉴别寄主之间以及它们与已知抗性基因的小麦品种进行杂交.并对亲本、F_1、F_2和一些回交子代的幼苗抗条锈性进行了评价。结果.中国166、HeinesⅦ、Fielder、Lee、Riebese147/51和moro分... 详细信息

利用了8个北美的条锈菌小种.在北美小麦不同条锈病鉴别寄主之间以及它们与已知抗性基因的小麦品种进行杂交.并对亲本、F_1、F_2和一些回交子代的幼苗抗条锈性进行了评价。结果.中国166、HeinesⅦ、Fielder、Lee、Riebese147/51和moro分别含有Yr1、Yr2、Yr6、Yr7、Yr9和Yr10抗性基因;Lemhi、Tyee中的一个基因.HeinesⅦ、moro、Druchamp、Stephens、Lee和Fielder两个基因之一与命名的Yr基因和其它以前描述的基因不同。Lembi中的基因可能与Riebese147/51或Druchamp和Stephens其中之一基因等位或紧密连锁。HeniesⅦ中的1个基因与Cappelle Despresz、Nord Desprez和Stephens中的基因等位或紧密连锁。Druchamp、Stephens和Yamhill有Yr3a或***与Stephens有1个相同基因.但与Yamhill不同。Yamhill(HeinesⅦ/ALba)有来自HeniesⅦ的Yr2和来自Alba的2个基因。其中之一不是Yr7.可能与Paha中的1个基因相同或紧密连锁。Lenhi中的Yr1、Yr7、Yr9和Y10基因和Paha中的1个基因都是显性。Lee中的第二个基因和Paha中的1个基因可能是隐性等位基因。Tyee中的Yr2、Yr6、Yr3a或Yr4a基因与Stephens、Druchamp或Fielder中两个基因之一依赖于小种和亲本(遗传背景)的不同.在杂交中表现为隐性或显性。中国166中的Yrl、Riebese147/51中的Yr9、Lemhi和Tyee中的基因是独立的。

关键词：小麦条锈病育种抗病性基因鉴定

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LN(LN=ND & Sm)-SUBSTITUTION FOR BI IN SRBI8TI7O27 DIELECTRIC CERAmICS

LN(LN=ND & SM)-SUBSTITUTION FOR BI IN SRBI8TI7O27 DIELECTRIC...

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第8届国际材联电子材料国际研讨会

作者： R.Z.Hou & x.m.chen Department of materials Science & Engineering, Zhejiang University, Hangzhou 310027,China

mixed-layer type bismuth compound SrBiTiO has been modified by Nd and Sm substitution with aim to suppress the dielectric loss and temperature coefficient around the room temperature. The dielectric properties were characterized together with the structure of the present modified ceramics. The Variating tendency of dielectric properties agreed well with the assumption that the introduction of Nd and Sm into

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High Sensitive Detection of Dichlorvos Pesticide Using Luminol Electrochemiluminescence

High Sensitive Detection of Dichlorvos Pesticide Using Lumin...

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第三十五届国际光谱会议

作者： x.m.chen Z.J.Lin x.chen~* Department of Chemistry and Key Laboratory of Analytical Sciences of the ministry of Education College of Chemistry and Chemical Engineering xiamen University xiamen 361005 China

＜正＞During recent years,organophosphorus pesticides are widely employed in agriculture because of their higher effectiveness and lower persistence compared with organochlorine *** pesticide（DDVP）is frequently used for the protection of ***,it does have a high acute ***,it is important to develop a simple,rapid and sensitive analytical method for the detection of ***

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micro—structural analysis of YBa2Cu3O7—x thin films grown on different substrates by x—ray techniques

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Beijing Synchrotron Radiation Facility 2001年第2期 54-60页

作者： C.x.Liu m.xu W.H.Tang x.m.chen L.S.Wu N.Yang Z.H.mai K.Tao J.G DepartmentofmaterialsScience TsinghuaUniversityBeijing100083china DepartmentofPhysics TheUniversityofHongKongPokfulamRoadHongKongchina InstituteofPhysicsandCenterforCondensedmatterPhysics Chinese

YBa2Cu3Ox(YBCO) thin films grown on different substrates with and/or without Eu2CuO4(ECO) buffer layer were investigated by x-ray wide angle diffraction,reflection,diffuse scattering and *** show that for the yttria stabilized ZrO2(YSZ) substrate,the presence of an ECO buffer layer improves the crystalline quality of the YBCO film,while a negative effect is observed for the SrTiO3(STO) *** lateral correlation length for a sample grown on a YSZ substrate with ECO buffer Layer is much greater than grown on an STO *** STO substrate used has mosaic structure.2001 Elsevier Science *** rights reserved.

关键词：微观结构 x射线衍射分析 YBa2Cu3O7薄膜钇钡铜复合氧化物薄膜缓冲层薄膜生长

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Interfacial stress engineering toward enhancement of ferroelectricity in Al doped HfO_(2)thin films

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Chinese Physics B 2024年第9期33卷 637-643页

作者： S x chen m m chen Y Liu D W Cao G J chen Department of microelectronics Jiangsu UniversityZhenjiang 212013China Department of Physics Jiangsu UniversityZhenjiang 212013China Guangdong–Hong Kong–macao Joint Laboratory for Intelligent micro-Nano Optoelectronic Technology Foshan UniversityFoshan 528225China

Ferroelectric HfO_(2)has attracted much attention owing to its superior ferroelectricity at an ultra-thin thickness and good compatibility with Si-based complementary metal-oxide-semiconductor(CmOS)***,the crystallization of polar orthorhombic phase(o-phase)HfO_(2)is less competitive,which greatly limits the ferroelectricity of the as-obtained ferroelectric HfO_(2)thin ***,the crystallization of o-phase HfO_(2)can be thermodynamically modulated via interfacial stress *** this paper,the growth of improved ferroelectric Al doped HfO_(2)(HfO_(2):Al)thin films on(111)-oriented Si substrate has been *** analysis has suggested that nonpolar monoclinic HfO_(2):Al grown on(111)-oriented Si substrate suffered from a strong compressive strain,which promoted the crystallization of(111)-oriented o-phase HfO_(2)in the as-grown HfO_(2):Al thin *** addition,the in-plane lattice of(111)-oriented Si substrate matches well with that of(111)-oriented o-phase HfO_(2),which further thermally stabilizes the o-phase HfO_(2).Accordingly,an improved ferroelectricity with a remnant polarization(2P_(r))of 26.7C/cm^(2) has been *** results shown in this work provide a simple way toward the preparation of improved ferroelectric HfO_(2)thin films.

关键词： improved ferroelectricity interfacial stress engineering compressive strain HfO_(2)

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