检索结果-南通市图书馆

Absence of superconductivity in Nd0.8Sr0.2NiOx thin films without chemical reduction

Rare Metals 2020年第4期39卷 368-374页

作者： Xiao-Rong Zhou Ze-Xin Feng Pei-Xin Qin Han Yan Shuai Hu Hui-Xin Guo Xiao-Ning Wang Hao-Jiang Wu Xin Zhang Hong-Yu Chen Xue-Peng Qiu Zhi-Qi Liu School of Materials Science and Engineering Beihang UniversityBeijing 100191China Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology and Pohl Institute of Solid-State PhysicsSchool of Physics Science and EngineeringTongji UniversityShanghai 200092China

The recently reported 9-15 K superconductivity in Nd0.8Sr0.2NiO2/SrTi03 heterostructures that were fabricated by a soft-chemical topotactic reduction approach based on precursor Nd0.8Sr0.2NiO3 thin films deposited on SrTiO3 substrates,has excited an immediate surge of research *** explore an alternative physical path instead of chemical reduction to realizing superconductivity in this compound,using pulsed laser deposition,we systematically fabricated 63 Nd0.8Sr0.2NiOx(NSNO)thin films at a wide range of oxygen partial pressures on various oxide *** measurements did not find any signature of superconductivity in all the 63 thin-film *** the oxygen content reducing in the NSNO films by lowering the deposition oxygen pressure,the NSNO films are getting more resistive and finally become ***,we tried to cap a 20-nm-thick amorphous LaAlO3 layer on a Nd0.8Sr0.2NiO3 thin film deposited at a high oxygen pressure of 20 Pa to create oxygen vacancies on its surface and did not succeed in obtaining higher conductivity *** experimental results together with the recent report on the absence of superconductivity in synthesized bulk Nd0.8Sr0.2NiO2 crystals suggest that the chemical reduction approach could be unique for yielding superconductivity in NSNO/SrTiO3 ***,SrTiO3 substrates could be reduced to generate oxygen vacancies during the chemical reduction process as well,which may thus partially contribute to conductivity.

关键词： Superconductivity Nd0.8Sr0.2NiOx Thin films chemical reduction

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

Size-dependent melting properties of Sn nanoparticles by chemical reduction synthesis

引用

Transactions of Nonferrous Metals Society of China 2010年第2期20卷 248-253页

作者：邹长东高玉来杨斌翟启杰 Shanghai Key Laboratory of Modern Metallurgy and Materials Processing Shanghai University

Tin nanoparticles with different size distribution were synthesized using chemical reduction method by applying NaBH4 as reduction *** Sn nanoparticles smaller than 100 nm were less agglomerated and no obviously *** melting properties of these synthesized nanoparticles were studied by differential scanning *** melting temperatures of Sn nanoparticles in diameter of 81,40,36 and 34 nm were 226.1,221.8,221.1 and 219.5？欲*** size-dependent melting temperature and size-dependent latent heat of fusion have been *** size-dependent melting properties of tin nanoparticles in this study were also comparatively analyzed by employing different size-dependent theoretical melting models and the differences between these models were *** results show that the experimental data are in accordance with the LSM model and SPI model,and the LSM model gives the better understanding for the melting property of the Sn nanoparticles.

关键词： Sn nanopartiele chemical reduction melting size-dependent property

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

Preparation of copper nanoparticles by chemical reduction method using potassium borohydride

引用

Transactions of Nonferrous Metals Society of China 2010年第S1期20卷 240-244页

作者：张秋利杨志懋丁秉钧兰新哲郭莹娟 School of Metallurgical Engineering Xi’an University of Architecture and Technology School of Science Xi’an Jiaotong University

High dispersive copper nanoparticles were prepared by chemical reduction method using potassium borohydride as reducing *** effects of reactant ratio,concentration of CuSO4,reaction temperature,and dispersant on the size of product and conversion rate were *** morphologies of copper nanoparticles were characterized by scanning electron *** results show that the optimum process conditions are as follows:the molar ratio of KBH4 to CuSO4 is 0.75(3:4),concentration of CuSO4 is 0.4 mol/L,reaction temperature is 30℃,and dispersant is n-butyl *** average particles size of copper powders with spherical shape gained is about 100 nm.

关键词： copper nanoparticles potassium borohydride chemical reduction

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 Fe-Ni-B and Fe-Cr-B Ultrafine Amorphous Alloy Powders Prepared by chemical reduction

引用

Journal of Iron and Steel Research International 1996年第1期3卷 19-23页

作者： Gang Bangwei Tan Zhaosheng Yi Ge Wang Haiquan Liu Zhihui Wang Jianwen Cao Meng International Center for Material Physics Academic Sinica Department of Applied Physics Hunan University

Ultrafine amorphous alloy powders of spherical shape with diameters from 10 to 50nm for Fe-Ni-B and Fe-Cr-B were prepared by chemical reduction. The amorphous structure of two powders was identified by X-ray diffraction. The B concentrations for the two alloy systems did not change dramatically, as the preparation condition changed. An oxide film covered up the powders. The maximum magnetization decreased as increasing the content of Ni or Cr.

关键词： ultrafine powder amorphous alloy structure magnetic property chemical reduction

来源：

维普期刊数据库

同方期刊数据库

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

Synthesis of Cu nanoparticles by chemical reduction method

引用

Transactions of Nonferrous Metals Society of China 2019年第7期29卷 1510-1515页

作者： M. S. AGUILAR R. ESPARZA G. ROSAS Instituto de Investigación en Metalurgia y Materiales UMSNH Morelia Michoacán 58000 Mexico Centro de Física Aplicada y Tecnología Avanzada UNAM Santiago de Querétaro 76230 Mexico

Cu nanoparticles (CuNPs) have been synthesized through an easy route by chemical reduction at room temperature. The Cu^2+ ions were reduced and stabilized with sodium borohydride and polyvinylpyrrolidone, respectively. The effect of the variation of the reducing agent/precursor-salt (RA/PS) ratio on the size and morphology of the CuNPs was evaluated. The synthesized material was studied by ultraviolet-visible (UV-Vis) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The UV-Vis spectra showed a CuNPs plasmon peak at 569 nm and another peak belonging to Cu2O at 485 nm. XRD analysis showed the fcc-Cu phase with a small amount of fcc-Cu2O compound. SEM and TEM studies displayed that small semispherical CuNPs of approximately 7 nm were obtained at the RA/PS ratio of 2.6. The excess of polyvinylpyrrolidone stabilizer played an essential role in preventing CuNPs oxidation. On the other side, Cu2O polyhedral particles with larger sizes up to 150 nm were identified in the RA/PS ratio range of 2.0-1.84. In addition, Cu2O particles having star morphologies with quantum confinement at their tips were obtained at the RA/PS ratio of 1.66.

关键词： Cu nanoparticles NaBH4 chemical reduction polyvinylpyrrolidone stabilization Cu2O

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

chemical reductive technologies for the debromination of polybrominated diphenyl ethers: A review

引用

Journal of Environmental Sciences 2023年第5期127卷 42-59页

作者： Ming Lei Yao Tang Lihua Zhu Heqing Tang College of Resources and Environmental Science South-Central Minzu UniversityWuhan 430074China School of Chemistry and chemical Engineering Huazhong University of Science and TechnologyWuhan 430074China

Polybrominated diphenyl ethers(PBDEs)are widely used as brominated flame retardants,which had attracted amounts of attention due to their harmful characteristics of high toxicity,environmental persistence and potential *** chemical reductive debromination technologies have been developed for the debromination of PBDEs,including photolysis,photocatalysis,electrocatalysis,zero-valent metal reduction,chemically catalytic reduction and mechanochemical *** review aims to provide information about the degradation thermodynamics and kinetics of PBDEs and summarize the degradation mechanisms in various *** to the comparative analysis,the rapid debromination to generate bromine-free products in an electron-transfer process,of which photocatalysis is a representative one,is found to be relatively difficult,because the degradation rate of PBDEs depended on the Br-rich phenyl ring with the lowest unoccupied molecular orbital(LUMO)*** the contrary,the complete debromination occurs easily in other systems with active hydrogen atoms as the main reactive species,such as chemically catalytic reduction *** review provides the knowledge on the chemical reductive technique of PBDEs,which would greatly help not only clarify the degradation mechanism but also design the more efficient system for the rapid and deep debromination of PBDEs in the future.

关键词： Polybrominated diphenyl ethers (PBDEs) Debromination chemical reduction Electron transfer Hydrogenation

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

Effects of PVP on the preparation and growth mechanism of monodispersed Ni nanoparticles

引用

Rare Metals 2008年第6期27卷 642-647页

作者： LIU Xiaodan GUO Min ZHANG Mei WANG Xidong GUO Xiao CHOU Kuochih Department of Physical Chemistry University of Science and Technology Beijing Beijing 100083 China College of Engineering Peking University Beijing 100871 China

Monodispersed Ni nanoparticles were successfully prepared by chemical reduction with hydrazine hydrate in ethylene glycol. The effect of the amount of polyvinylpyrrolidone （PVP-K30） on the preparation of Ni nanoparticles was investigated. X-ray diffraction （XRD）, transmission electron microscopy （TEM）, and high resolution transmission electron microscopy （HRTEM） were employed to characterize the nickel powders. The average nickel particle size can be controlled from 103 nm to 46 ran with increasing the mass ratio of PVP to NiCl2·6H2O. The particles are spherical in shape and are not agglomerated. A possible extensive mechanism of nickel nanoparticle formation has been suggested.

关键词： Ni nanoparticles nucleation mechanism chemical reduction PVP

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

Preparation of fine copper powders and their application in BME-MLCC

引用

Journal of University of Science and Technology Beijing 2006年第3期13卷 250-255页

作者： Songping Wu Haoli Qin Pu Li College of Chemistry South China University of Technology Guangzhou 510641 China

The preparation of fine copper powders by chemical reduction method was investigated. The reaction of [Cu（NH3）4]2^＋ complex with hydrazine hydrate gives spherical monodispersed fine copper powders. The spherical copper powder with a uniform size of 3.5 ± 0.5 μtm was processed to obtain flake copper powder having a uniform size of 8-10 μm, excellent dispersibility and uniform shape. The spherical copper powder of 2.5 ±0.3 μm in size, flake copper, glass frit and vehicle were mixed to prepare copper paste, which was fired in 910-920℃ to obtain BME-MLCC （base metal multilayer ceramic capacitor） with a dense surface of end termination, high adhesion and qualified electrical behavior. Polarized light photo and SEM were employed to observe the copper end termination of BME-MLCC. The rough interface from the interracial reaction between glass and chip gives high adhesion.

关键词： spherical copper powder flake copper powder chemical reduction BME-MLCC

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 depolymerization pathways and mechanism of alkali lignin over a Ni_(1.2)-ZrO_(2)/WO_(3)/γ-Al_(2)O_(3)catalyst

引用

Chinese Journal of chemical Engineering 2022年第8期35卷 191-201页

作者： Xinyu Lu Dandan Wang Haoquan Guo Pengcheng Xiu Jiajia Chen Yu Qin Hossain Mahmud Robin Chaozhong Xu Xingguang Zhang Xiaoli Gu Co-Innovation Center for Efficient Processing and Utilization of Forest Products College of Chemical EngineeringNanjing Forestry UniversityNanjing 210037China Department of Chemistry School of ScienceUniversity of Shanghai for Science and TechnologyShanghai 200093China

This study performed catalytic depolymerization of alkali lignin over Ni-based *** of different promoters(Zr and W),Ni loadings,reaction temperatures,and the addition of formic acid and catalyst on lignin conversion and products distribution were all *** result showed that the highest oil yield(40.1%(mass))was obtained at 240℃over Ni_(1.2)/γ-Al_(2)O_(3) promoted by Zr and W *** analysis indicates that Zr and W species prefer to lignin depolymerization while Ni active phase prefer to hydrodeoxygenation and *** interconversion of products derived from lignin depolymerization was determined by gas chromatography-mass spectrometer,which demonstrated that phenolic compounds were dominant products in all lignin derived bio-oils,wherein the proportion of vanillin was highest(65.7%)at 180℃,while that of alkyl guaiacols increased with the increase of temperature(from 12.45%at 180℃ to 66.67%at 240℃).Residual lignin obtained after lignin depolymerization was also investigated for detecting differences on functional groups,wherein the disappearing peaks at 1511 cm^(-1)(stretching of aromatic rings),1267,1215 and 1035 cm^(-1)(vibrations of guaiacyl and syringyl units)were detected by Fourier transform infrared ***,the higher O/C ratio measured by elemental analysis also confirmed that alkali lignin was depolymerized effectively under mild conditions.

关键词： Alkali lignin Formic acid chemical reduction Phenolic compounds

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

chemical synthesis and coercivity enhancement of Nd2Fe14B nanostructures mediated by non-magnetic layer

引用

Nano Research 2020年第4期13卷 1141-1148页

作者： Kai Zhu Junjie Xu Xiaobai Wang Wei Li Kesong Tian Yanglong Hou Beijing Key Laboratory for Magnetoelectric Materials and Devices(BKLMMD) Beijing Innovation Centre for Engineering Science and Advanced TechnologyDepartment of Materials Science and EngineeringCollege of EngineeringPeking UniversityBeijing 100871China Academy for Advanced Interdisciplinary Studies Peking UniversityBeijing 100871China

High-performance Nd2Fei4B magnets have been widely required in various fields recently due to the lightweight and miniaturization of *** this work,we synthesize Nd2Fei4B nanostructures with tunable magnetic properties through surfactant-assisted high energy ball milling(SAHEBM)process,achieving prominently enhanced coercivity by forming non-magnetic layers as grain boundary *** the reduction annealing process was carried out as pellet with Ca,the coercivity increased from 0.8 kOe to over 3 kOe as Nd2Fei4B powder,which is proved to be the contribution of the chemical diffusion of Nd elements and the formation of Nd-rich layer as magnetic insulating *** addition,two-dimensional graphene oxide(GO)was employed to build extra grain boundary,by which the coercivity of the core@dual-shell structure can achieve up to 8 kOe,tenfold of the original *** intrinsic mechanism indicated that the Nd-diffusion induced Nd-rich phase along with the reduced GO in the system could form non-magnetic layer as grain boundary and magnetically isolate the adjacent grains,significantly enhancing the exchange coupling *** work markedly opens up an effective approach for the chemical preparation of high-performance Nd2Fe14B nanostructured magnets,especially after post treatment,and gives an insight on the interactions at nanoscale.

关键词： Nd2Fei4B nanostructures chemical reduction diffusion process grain boundary graphene oxide coercivity enchantment

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

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：