检索结果-南通市图书馆

Mechanically Driven Alloying and Structural Evolution of Nanocrystalline Fe_(60)Cu_(40) Powder

Journal of materials science & technology 1997年第4期13卷 354-358页

作者： Yuanda DONG and Xueming MA(School of materials science and Engineering, Shanghai university, Shanghai 200072, china)Yuanzheng YANG(dept. of Mechanical Engineering(2), South china university of technology, Guangzhou 510641, china)Fangxin liU and Genmiao WA School of materials science and Engineering Shanghai University Shanghai 200072 China dept. of Mechanical Engineering(2) South China University of Technology Guangzhou 510641 China Lab. of Structure Analysis University of Science and Technology of China Hefei 230026 China

Highly supersaturated nanocrystalline fcc Fe60Cu40 alloy has been prepared by mechanical alloying of elemental powders. The phase transformation is monitored by X-ray diffraction (XRD),Mossbauer spectroscopy and extended X-ray absorption fine structure (EXAFS). The powder obtained after milling is of single fcc structure with grain size of nanometer order. The Mossbauer spectra of the milled powder can be fitted by two subspectra whose hyperfine magnetic fields are 16 MA/m and 20 MA/m while that of pure Fe disappeared. EXAFS results show that the radial structure function (RSF) of Fe K-edge changed drastically and finally became similar to that of reference Cu K-edge, while that of Cu K-edge nearly keeps unchanged in the process of milling. These imply that bcc Fe really transforms to fcc structure and alloying between Fe and Cu occurs truly on an atomic scale. EXAFS results indicate that iron atoms tend to segregate at the boundaries and Cu atoms are rich in the fcc lattice. Annealing experiments show that the Fe atoms at the interfaces are easy to cluster to α-Fe at a lower temperature, whereas the iron atoms in the lattice will form γ-Fe first at temperature above 350℃, and then transform to bcc Fe

关键词： Mechanically Driven Alloying and Structural Evolution of Nanocrystalline Fe MA Cu Powder Figure

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Investigation of Instability of Lattice of Bi_2Sr_2CaCu_2O_x

引用

Journal of materials science & technology 1996年第3期12卷 175-179页

作者： Han ZHANG and Qingrong FENG (dept. of physics, Peking university, beijing 100871, china)Y.Zhao(School of materials science and Engineering, university of New South Wales, Sydney 2052, NSW, Australia)F.Ritter and W.Assmus (Physikalisches Institut, J.W.Goet dept. of physics Peking University Beijing 100871 China School of materials science and Engineering University of New South Wales Sydney NSW 2052 Australia Physikalisches Institut J.W.Goethe Universität 60054 Frankfurt am Main Germany

Bi2Sr2CaCu2Ox superconductor was studied by differential scanning calorimetry (DSC) and thermogravimetry (TG) in different atmospheres. It is discovered that there is a thermal anomaly in the DSC curve, associated with a weight loss in the TG curve before the melting of the sample. Careful thermal analysis and high temperature X-ray diffraction reveal that the thermal anomaly and the weight loss show an instability of the crystalline Iattice. By annealing the sample in oxygen and argon, respectively and then by TC measurement and thermal analysis, the coincidence of transition temperature with the instability is found. The coincidence is further confirmed by Y-doped 2212 phase.

关键词： Sr Bi

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Grain Growth Kinetics and Debye Temperature of Nanometer TiO_2 Powders Prepared by a Sol-gel Process

引用

Journal of materials science & technology 1994年第3期10卷 213-216页

作者： Ju LUO Xingzhao DING Benpei CHEN and Jie KONG(Institute of Solid State physics, Academia Sinica, Hefei, 230031, china)Yuanda DONG(dept. of Metallurgy and materials, Shanghai university of technology, Shanghai, 200072, china) Inst of Solid State physics Academia Sinica Hefei China

The development of microstructure of nanometer TiO2 powders prepared by a sol-gel process was systematically studied. Grain growth was mon itored using X-ray diffraction (XRD) and transmission electron microscopy (TEM). and the Debye temperature of anatase crystallites was determined. It was found that the grain size of the powders increased slowly with annealing temperature up to 773 K. but grew rapidly in the temperature range of 773-1273K. The activation energies (Ea) for the growth of anatase crystallites in the two temperature regions were calculated to be 16 and 90 kJ / mol, respectively. The Debye temperatures of nanocrystalline anatase powders were all lower than that of microcrystalline anatase. which implies that the bonding force between Ti and O atoms in nanocrystalline TiO2 shourd be smaller than that in microcrystalline state. However. it was noted that the Debye temperature of nanocrystalline anatase increased with the decrease of grain size. This may be attributed to the enhancement in atomic bonding force due to the existence of high surface tension in nanocrystalline powders

关键词： Powders

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Electron Spin Resonance of FeCl_3-filled Polyvinylidene Fluoride

引用

Journal of materials science & technology 1997年第3期13卷 194-198页

作者： A.Tawansi H.I.Abdel-Kader and E.M.Abdel-Razek(dept. of physics, Faculty of science, Mansoura university, 35516, Egypt)M I Ayad(dept. of chemistry Almonofeya university, Shebeen E1-Koam, Egypt) dept. of physics Faculty of Science Mansoura University Egypt dept. of chemistry Almonofeya University Shebeen El-Koam Egypt

Electron spin resonance (ESR) measurements were carried out at room temperature (=294 K),for FeCl3-filled polyvinylidene fluoride (PVDF) films, over the filling mass fraction range of 0 详细信息

Electron spin resonance (ESR) measurements were carried out at room temperature (=294 K),for FeCl3-filled polyvinylidene fluoride (PVDF) films, over the filling mass fraction range of 0ling level on the following ESR parameters are discussed: signal asymmetry line width, g-factor, relaxation time, spin (and orbital) magnetic moment, number of unpaired electrons per Fe ion and density of spin electrons.

关键词： Figure Spin

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Concentration and Temperature Dependence of Electrical Conductivity in Thermally Stable Chromium Polyacrylate

引用

Journal of materials science & technology 1995年第6期11卷 443-446页

作者： S. U.Rehman M.Siddique and Farid A.Khwaja(materials Research Laboratory, dept. of physics, Quaid-i-Azam university, Islamabad, Pakistan)M.S.Zafar(dept. of physics, university of the Punjab, Lahore, Pakistan) Quaid-i-Azam Univ Islamabad Pakistan

Electrical conductivity of chromium polyacrylate with dopant concentration 30, 40 and 50 wt-% of chromium has been measured over a broad range of temperatures (303 K to 383 K).The electrical conductivity shows dependence on temperature, as well as, level of doping. The conductivity is considered to be due to thermal hopping motion of localized charge carriers,which are believed to be polarons, in the temperature range 303 K to 323 K and for T>343 K,whereas. it is metal-like in the temperature range 323 K to 343 K

关键词： Concentration and Temperature Dependence of Electrical Conductivity in Thermally Stable Chromium Polyacrylate

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Mossbauer Spectroscopic Studies on a Supersaturated Solid Solution of Fe-Cu Formed by Mechanical Alloying

引用

Journal of materials science & technology 1994年第2期10卷 135-138页

作者： Yuanzheng YANG and Xueming MA (Institute of Solid State physics, Academia Sinica, Hefei, 230031, china)(To whom correspondence should be addressed)Yuanda DONG(dept. of Metallurgy arid materials, Shanghai university of technology, Shanghai, 200072, china) Acad Sinica Hefei China

Mechanical alloying (MA) was employed to produce supersaturated solid solutions of Fe1-xCux,which is virtually immiscible under an equilibrium condition at ambjent temperature. The X-ray diffraction results show that the solutions formed in the concentration ranges of x≤0.1 5 and x≥0.40 are of bcc structure of iron and fcc structure of copper. respectively. For the region in ***, the alloy obtained is a mixture of bcc plus fcc phases. The Mossbauer spectrum of the solid solution of a single phase could be fitted by two sub-spectra with hyperfine magnetic fields of 200 and 250 kOe. respectively. suggesting that there must exist two forms of coordination in the solution. While to fit the spectrum for the solution with mixed structu re. three Sub-spectra. including a spectrum of α-Fe, should be used. The variation of the Mossbauer spectra of Fe60Cu40 with milling time as well as annealing temperature was systematically studied. This may be ascribed to the changes of the number of nearest neighboring atoms of iron in the processes of formation and decomposition of the solid solution during milling and annealing

关键词： Fe Cu ssbauer Spectroscopic Studies on a Supersaturated Solid Solution of Fe-Cu Formed by Mechanical Alloying

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

State Properties of Strongly Coupled Electron-Phonon Systems with Correlated Displacement and Squeezing

引用

Journal of materials science & technology 1999年第4期15卷 369-372页

作者： Xiaofeng PANG(dept. of physics, Xiangtan university, Xiangtan 411105, china)E-mail: pangxf@*** dept. of physics Xiangtan University Xiangtan 411105 China

The correlation effects among the polaronic and one-phonon coherent and two-phonon squeezed states induced by the motion and density fluctuation of the electrons change the state and properties of the strongly coupled electron-phonon systems and make the ground state energy decrease, the binding energy of the polarons increase, the CDW ordering enhance and the quantum fluctuation effect of the lattice phonons weaken.

关键词： Rev exp

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Insights into ionic association boosting water oxidation activity and dynamic stability

引用

Journal of Energy chemistry 2024年第2期89卷 99-109,I0004页

作者： Zanling Huang Shuqi Zhu Yuan Duan Chaoran Pi Xuming Zhang Abebe Reda Woldu Jing-Xin Jian Paul K.chu Qing-Xiao Tong liangsheng Hu Xiangdong Yao Department of chemistry and Key Laboratory for Preparation and Application of Ordered Structural materials of Guangdong Province Shantou UniversityShantou 515063GuangdongChina chemistry and Chemical Engineering Guangdong Laboratory Shantou 515063GuangdongChina State Key Laboratory of Refractories and Metallurgy and Institute of Advanced materials and Nanotechnology Wuhan University of Science and TechnologyWuhan 430081HubeiChina Department of physics Department of Materials Science and Engineeringand Department of Biomedical EngineeringCity University of Hong KongTat Chee AvenueKowloonHong KongChina School of Advanced Energy Sun Yat-sen University(Shenzhen)Shenzhen 518107GuangdongChina

There have been reports about Fe ions boosting oxygen evolution reaction(OER)activity of Ni-based catalysts in alkaline conditions,while the origin and reason for the enhancement remains ***,we attempt to identify the activity improvement and discover that Ni sites act as a host to attract Fe(Ⅲ)to form Fe(Ni)(Ⅲ)binary centres,which serve as the dynamic sites to promote OER activity and stability by cyclical formation of intermediates(Fe(Ⅲ)→Fe(Ni)(Ⅲ)→Fe(Ni)-OH→Fe(Ni)-O→Fe(Ni)OOH→Fe(Ⅲ))at the electrode/electrolyte interface to emit O_(2).Additionally,some ions(Co(Ⅱ),Ni(Ⅱ),and Cr(Ⅲ))can also be the active sites to catalyze the OER process on a variety of *** Fe(Ⅲ)-catalyzed overall water-splitting electrolyzer comprising bare Ni foam as the anode and Pt/Ni-Mo as the cathode demonstrates robust stability for 1600 h at 1000 mA cm^(-2)@~1.75 *** results provide insights into the ioncatalyzed effects boosting OER performance.

关键词： Oxygen evolution reaction Fe(Ⅲ)-catalysis Ni-Fe binary active centers Ion-catalyzed effects Robust stability

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Study on Hydrophobic and Mechanical Properties of Fluoro-Carbon Film

引用

稀有金属材料与工程 2011年第S4期40卷 199-202页

作者： Ma Guojia1,2,lin Guoqiang2,Sun Gang1,Wu Hongchen1 1Department of physics and Optoelectronic technology,Dalian university of technology,Dalian 116024,china2National Key Laboratory of science and technology on Power Beam Processes,beijing Aeronautical Manufacturing technology Research Institute,beijing 100024,china beijing Aeronaut Mfg Technol Res Inst Natl Key Lab Sci & Technol Power Beam Proc Beijing 100024 Peoples R China Dalian Univ Technol Dept Phys & Optoelect Technol Dalian 116024 Peoples R China

The purpose of this paper is to investigate the hydrophobic and mechanical behavior of the fluoro-carbon film on the ***-carbon films were fabricated on C/C and C/SiC composite by microwave ECR chemical vapor deposition combined with plasma source ion implantation technology (PSII).The films were investigated in terms of the surface morphology,chemical composition,hydrophobic behavior and mechanical *** hydrophobic property was determined by means of contact angle measurements,chemical bond structure was analyzed by fourier-transform infrared spectrum,and critical loading were measured by *** results showed that the fluorine presented mainly in the forms of CF2 group and C=CFx (x=1,2) in the film,the addition of fluorine to the carbon film had a critical influence on the *** force microscopy (AFM) were used for investigating the effect of surface morphology and roughness on hydrophobicity,it showed that fluoro-carbon films with appropriate surface morphology and roughness could achieve excellent hydrophobicity.

关键词： fluoro-carbon film microwave ECR CVD PSII hydrophobicity.

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Studies of Atomic Structure and Physical Properties of Metal Clusters in MgO by HREM and Nano-probe Methods

引用

Journal of materials science & technology 1997年第4期13卷 265-270页

作者： Nobuo Tanaka (dept. of Applied physics, School of Engineering, Nagoya university, Nagoya, 464-01, Japan) dept. of Applied physics School of Engineering Nagoya University Nagoya 464-01 Japan

Nanometer-sized metal clusters were prepared inside single crystalline MgO films by vacuum co-deposition of metals and MgO. The atomic structure was studied by high-resolution electron microscopy (HREM) and nm-area electron diffraction. The size of the clusters is ranging from 1 nm to 3 nm without those larger than 5 nm, and most of them have definite epitaxial orientations with the MgO matrix films. The character of the composite films is very much useful for the studies of various kinds of physical properties with anisotroPy. The physical properties such as electric transport, magnetic, optical absorption, sintering and catalytic ones were thus measured on the same samples analyzed by HREM by using high sensitivity apparatus with interest of clarifying the retationship between the atomic structure and physical properties

关键词： Figure Nano Studies of Atomic Structure and Physical Properties of Metal Clusters in MgO by HREM and Nano-probe Methods HREM MgO

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：