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Electric characteristics of Nd_2O_3 doped BaTiO_3 ceramics

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Journal of Harbin Institute of Technology(New Series) 2003年第4期10卷 388-391页

作者：郝素娥韦永德 dept. of Applied chemistry Harbin Institute of Technology

Nd2O3 doped BaTiO3ceramics（the additive content was respectively 0.001, 0.002, 0.003, 0.005, 0.01 molar ratio）were prepared by Sol-Gel method to study their dielectric characteristics and electric conductivities through X-ray photoelectron spectrum （XPS）. The results showed that the dielectric characteristics of Nd2O3 doped BaTiO3 ceramics were improved by doping. When Nd2O3 content was 0.003 mol, the results were even better, the dielectric constant was increased, the dielectric loss was decreased, the Curie-temperature （Tc） was 110 ℃, and the frequency characteristic was also good. The resistivity of Nd2O3 doped BaTiO3 ceramics was lower than that of pure BaTiO3 ceramics, when Nd2O3 content was 0.001 mol,the resistivity was （2.364×）108 Ω·m, the smallest. The grain resistance of Nd2O3 doped BaTiO3 ceramics exhibited NTC effect, but the grain boundary resistance showed PTC effect, and the grain boundary resistance was larger than that of the grain resistance, so the PTC effect originated from the grain boundary. The analysis of the element binding energy through X-ray photoelectron spectrum were indicated that the quantivalence of Ba2+and Ti4+in Nd2O3 doped BaTiO3 ceramics was variable, and resulted in the improvement of the conductibility of BaTiO3 ceramics.

关键词： BaTiO3 导电性 Nd2O3 陶瓷材料 X射线光电子光谱

Effects of Hyperfine and Dopant Cation Interactions on theDC-Electrical Conductivity of MnZn Ferrites

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Journal of Materials Science & Technology 1997年第6期13卷 467-470页

作者： M.M.Abou Sekkina(Chem. dept., Faculty of Science, Tanta University, Tanta, Egypt)A.M.El-Sayed(Inorganic chemistry dept., National Research Centre, Dokki, Cairo, Egypt) Chem. dept. Faculty of Science Tanta University Tanta Egypt Inorganic chemistry dept. National Research Centre Dokki Cairo Egypt

Samples of undoped, and CuO, CaO, Al2O3 as well as V2O5 doped MnZn ferrite were prepared using standard ceramic method. The X-ray diffraction results for the base and doped ferrite samples show a single phase with spinel cubic structure. The Mossbauer spectrum of the base sample indicates line broadening and overlapping due to relaxation of magnetic dipoles. The temperature dependence of DC-electrical conductivity has been discussed on the basis of electronic conduction (electron hopping) and ionic conduction mechanism.

关键词： Effects of Hyperfine and Dopant Cation Interactions on theDC-Electrical Conductivity of MnZn Ferrites

Synthesis and Structures of New Borophosphates (B_(1-X)M_X)PO_4 (M=Mn,Fe,Co,Ni,Cu) with Orthorhombic Low-Cristobalite Type

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Chinese Chemical Letters 1999年第8期10卷 707-708页

作者： Cheng Hua XU Shao Jie LU Gui Ying DENG Fa Li QIU (Chengdu Institute of Organic chemistry. Chinese Academy of Sciences, Chengdu 610041) dept. of Materials Science Xiamen University Xiamen 361005 China dept. of chemistry Xiamen University Xiamen 361005 China

The first reported (B1-xMX)PO4 (M = Mn, Fe, Co, Ni, Cu) compounds were synthesized by high temperature solid state methods and the structures refined from X-ray powder data. The transition metal substitutions on the boron site stabilized the structure to the orthorhombic low-cristobalite type with average volumes per tetrahedral unit 30% larger than that in BPO4 and novel catalytic properties are expected. The magnetic data indicate the 3+ valences for the metals.

关键词： Transition-metal borophosphate,synthesis,structure magnetic property

Microstructure of Co-Ni-Al2O3 Composite Coatings by Electroforming

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Journal of Materials Science & Technology 2003年第Z1期19卷 133-134页

作者： Gang WU Ning LI Derui ZHOU Kurachi Mitsuo dept. of Applied chemistry Harbin Institute of Technology Harbin 150001 China1 Dept. of Applied Chemistry Harbin Institute of Technology Harbin 150001 China1 Dept. of Applied Chemistry Harbin Institute of Technology Harbin 150001 China1 Faculty of Engineering Kyoto University Kyoto 606-8283 Japan

The metal matrix composite coatings of Co-Ni-Al2O3 were studied by electrolytic codeposition of Co-Ni alloys and Al2O3 on a Cu substrate from a sulfamate electrolyte containing Al2O3 particles. It was illustrated from the examined results of SEM, AFM and XRD that surface morphology and microstructure of Co-Ni-Al2O3 coatings appear to be mainly influenced by variations in Co content. The high Co content coatings with hcp lattice structure have a more uniform and fine structure than that of low Co content coatings with fcc lattice structure. The codeposition of Al2O3 particles in Co-Ni alloys can not change the phase structure of solid solution, only affects the growth and orientation of crystal planes and mostly increase the d value of lattice.

关键词： Electroforming, Composite coatings, Cobalt-Ni alloys, Alumina

Structural Evolution of the Mn_(0.52)Sb_(0.48) Compound during High Energy Ball Milling

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Journal of Materials Science & Technology 1996年第6期12卷 434-438页

作者： Fuxing YIn and Nanju GU (dept. of Materials Science and Engineering, Hebei Institute of Technology, Tianjin 300130, China)T.Shigematsu and N.Naknishi (dept. of chemistry, Faculty of Science, Konan University, Kobe 658, Japan)(To whom correspondence should dept. of Materials Science and Engineering Hebei Institute of Technology Tianjin 300130 China dept. of chemistry Faculty of Science Konan University Kobe 658 Japan

The structural transitions of the NiAs-type Mn0.52Sb0.48 magneto-ordered compound, ball milled to different periods, have been characterized by X-ray diffraction and DSC analysis. On the basis of lattice parameter results a structural evolution mode with three stages is proposed. In the first stage lattice parameters keep nearly unchanged with the refinement of grains and increase of lattice strain. In the second stage, microstrain shows a lowering tendency accompanying the successive decreases of grain size. The X-ray revealed internal strain is found to be strains inside the lattice, which can be relaxed with new grain formation. The change of Tc is shown to be affected by the dimension of c axis, however the overall magnetization is continuously decreased with milling, due to the disordering process occurred in milling. Correspondent disordering mechanisms have been tentatively postulated and discussed according to the changes of lattice para meters.

关键词： Sb Ball Structural Evolution of the Mn Compound during High Energy Ball Milling

A New Convenient Synthesis of Pyridine-N-oxides

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Chinese Chemical Letters 1996年第10期7卷 907-908页

作者： Tao LU Xin Zhong SHI Yi Ming WU(dept.of Organic chemistry, China Pharmaceutical University,Nanjing, Jiangsu 210009) dept. of Organic chemistry China Pharmaceutical University Nanjing Jiangsu 210009

This paper describes the direct oxidation of pyridines to pyridine-N-oxides by means of 30% H2O2 in aq media in the presence of Na2WO4.2H(2)O as catalyst instead of with per-acids or 30% H2O2 in acetic acid. Good yiel... 详细信息

关键词： A New Convenient Synthesis of Pyridine-N-oxides

Coumarin-glycoside and Ferulate from Peucedanum decursivum

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Chinese Chemical Letters 2000年第4期11卷 315-318页

作者： Ling Yi KONG Nian Huan YAO (Department of Natural Medicinal chemistry, China Pharmaceutical University. Nanjing 210038) dept. of Natural Medicinal chemistry China Pharmaceutical University Nanjing 210038 China

Two new compounds named decuroside VI(1) and decursidate (2) were isolated from the roots of Peucedanum decursivum - a traditional Chinese medicine. Their structures were elucidated on the basis of chemical evidence a... 详细信息

关键词： Peucedanum decursivum decuroside VI decursidate

Clay-polymer Nanocomposites: Preparation, Properties, Future Applications and New Synthesis Approach of EPDM/clay Nanocomposites

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Journal of Harbin Institute of Technology(New Series) 2004年第2期11卷 138-145页

作者： S.J.AHMADI 黄玉东李伟 dept. of Applied chemistry Harbin Institute of Technology Harbin 150001 China

The synthtic routes, materials properties and future applications of clay-polymer nanocomposites are reviewed. Nannocomposites are composite *** contain particles in the size rang 1-100 nm. The particles generally have a high aspect ratio and a layered structure that maximizes bonding between the polymer and particle. Adding a small quantity of these additives (0.5% ～ 5% ) can increase many of the properties of polymer materials, such as tensile characteristics, heat distortion temperature, scratch resistance, gas permeability resistance, and flame retardancy. This new type of materials may be prepared via various synthetic routes comprising exfoliation adsorption, in-situ intercalative polymerization and melt intercalation. In this paper we report the new method for preparation EPDM-clay nanocomposites. The EPDM-clay nanocomposites were prepared by using two different approaches (direct and indirect). It is found that there is no difference between both methods but the direct method is easier, its cost is lower and industrially more practical. X-ray diffraction (XRD)and transmission electron microscopy (TEM) results showed a exfoliation structure. The mechanical properties of these nanocomposites significantly improved.

关键词：纳米合成有机粘土聚合物原位插入剥落 EPDM 乙烯丙烯二烯烃三远共聚物

Smudge on tinplate steel sheets and the effects of cathodic dichromate treatment

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Journal of Harbin Institute of Technology(New Series) 2001年第4期8卷 363-366页

作者：李宁李平黎德育 Mitsuo Kurachi dept. of Applied chemistry Harbin Institute of Technology Kyoto University

Smudge is black granules that scatter on tinplate sheet; it was formed during the process of plating and storing, and seriously affected the function and appearance of tinplate sheet. Reflowing and cathodic dichromate treatment (CDC) are two major phases in which smudge is produced. In this paper, the appearance and component of smudge was analyzed by means of whiteness meter, SEM and EDS quantitatively. Factors of CDC conditions was studied. Results of tests showed that whiteness measurement is convenient to evaluation of the degree of smudge and the effects of CDC on it , quantitatively.

关键词： tinplate smudge CDC whiteness meter