材料期刊网

A Coprecipitation Coating Synthesis of SiC/YAG Composites

Ning ZHANG , Hongqiang RU , Xudong SUN , Qingkui CAI

材料科学技术（英文）

The α-SiC in 0.5μm size powders were coated with Al2O3 and Y2O3 by a coprecipitation coating (CPC) method for fabrication of SiC/YAG composites. The same powder preparation was carried out by conventional mechanical mixing (MM) method for comparison. Two kinds of SiC/YAG composites were manufactured by pressureless sintering using the different powders, named CPC composite and MM composite thereafter respectively. It is shown that the CPC composite has the advantages of homogeneous distribution of YAG phase and of being sintered to high density at a low temperature, 100℃ lower than that of MM composite. The strength (573 MPa) and hardness (23.3 GPa) of the CPC composite are significantly higher than those (323 MPa and 13.5 GPa) of the MM composite, respectively.

关键词: Coprecipitation , null , null

Site preference of Ru in NiAl and valence band structure of NiAl containing Ru: First-principles study and photoelectron spectrum

Philosophical Magazine Letters

The site preference of Ru in NiAl was studied using first-principles calculations. The calculation of formation energies indicated that the site preference of Ru was on the Ni sites. The valence band (VB) structures of the NiAl alloys were investigated by photoelectron spectroscopy. The VB spectra of the NiAl-Ru alloy was shifted away from the Fermi level so that the Ni d-band centroid moved to a higher energy by 7.77 eV as Ru was added. Such a shift revealed that the Ni-Ru interactions gave a significant contribution to the VB structure of the NiAl-Ru alloy.

关键词: NiAl-Ru alloys;valence band structure;Auger electron spectroscopy;(AES);auger parameter;ab-initio;alloys;magnetism;additions;system;energy;atoms;cr;re

Structural rearrangements of Ru nanoparticles supported on carbon nanotubes under microwave irradiation

Chemical Communications

The structure evolution of twinned Ru nanoparticles supported on carbon nanotubes rearranging into Ru single nanocrystals under the microwave irradiation and the exposed surface of Ru single crystals were observed, which provided new insights into synthesis and application of metal nanoparticle catalysts.

关键词: layered double hydroxides;aberration-corrected tem;ammonia;decomposition;assisted preparation;low-temperature;particle-size;catalysts;nanocomposites;nanocrystals;stability

Ru/CNFs催化剂催化氨分解制氢

段学志 , 周静红 , 钱刚 , 李平 , 周兴贵 , 陈德

催化学报 doi:10.1016/S1872-2067(10)60097-6

研究了鱼骨式碳纤维(CNFs)和管式碳纤维(CNTs)负载Ru催化剂的氨分解反应活性.结果表明,Ru/CNFs催化剂上氨分解活性高于Ru/CNTs催化剂.通过改变Ru负载量或载体表面的含氧基团来调节Ru的粒径.Ru的活性位随着Ru颗粒尺寸的增大而增加.CNFs上的含氧基团对Ru颗粒的氨分解活性影响很大.在相同粒径的Ru颗粒上,CNFs表面的含氧基团增加了Ru的活性.

关键词: 碳纤维 , 钉 , 负载型催化剂 , 氨分解 , 氢气 , 结构敏感性

Ag-Pd-Gd-20Ru和Ag-Pd-Gd-50Ru四元系部分相图研究

张康侯 , 徐云 , 李曲波

贵金属 doi:10.3969/j.issn.1004-0676.2001.04.001

采用X-射线衍射、扫描电镜和显微金相分析等方法研究了Ag-Pd-Ru-Gd四元系相图的富Ag-Pd-Ru区域(Gd＜25at%).测定了Ag-Pd-Gd-20Ru和Ag-Pd-Gd-50Ru四元系相图的700℃部分等温截面.这两个等温截面上都分别含有3个二相区:Pd(Ag)+(Ru),(Ru)+Ag51Gd14,(Ru)+Pd3Gd;3个三相区:Pd(Ag)+Pd3Gd+(Ru),Pd(Ag)+Ag51Gd14+(Ru),Pd3Gd+Ag51Gd14+(Ru);1个四相区:Pd(Ag)+Pd3Gd+Ag51Gd14+(Ru).这2个截面上都不含有单相固溶区,也未发现新的四元中间相.

关键词: 银 , 钯 , 钌 , 钆 , Ag-Pd-Ru-Gd四元系 , 相图

Suppression of ferroelectricity and quantum fluctuations in Ru-doped TbMnO3

Applied Physics a-Materials Science & Processing

We investigate the effects of Ru-doping in polycrystalline TbMn1-x Ru (x) O-3 (xa parts per thousand currency sign0.10) on the multiferroicity. It is observed that the Ru substitution gradually melts away the dielectric anomaly at the ferroelectric transition point and the ferroelectricity by suppressing the polarization, accompanied with a surprising low-temperature dielectric plateau. While it is reasonable to observe the significant suppression of ferroelectricity, owing to the fact that the Ru-doping disrupts the Mn spiral spin ordering and reduces the Mn-Mn spin angle, quantum fluctuations associated with the Ru substitution, responsible for the low-temperature dielectric plateau, seems to be significant.

关键词: polarization

A THEORETICAL-STUDY OF SI CHEMISORPTION ON RU(001) SURFACE

Physica Status Solidi B-Basic Research

The embedded cluster model is used to study the electronic structure of Si chemisorption on Ru(001) surface, within the framework of local-density theory regime. The Kohn-Sham equation is solved self-consistently using the discrete variational method. The most possible adsorbed site of Si is obtained by calculating the adhesive energy for two positions. The distributions of Si 3s, Si 3p, and Ru 4d orbitals are clearly identified by our calculations, The interaction between Si adatom and Ru(001) surface and its influence on the d-d interatomic interaction of Ru atoms are also discussed.

关键词: electronic-structure;silicon;photoemission;silicides;ruthenium;metal;cu

电沉积制备Pt-Ru合金电极

赵沧燕 , 刘小东 , 田建华 , 马勉军

电镀与精饰 doi:10.3969/j.issn.1001-3849.2008.09.001

采用电沉积法制备Pt-Ru合金电极.研究了电解液中Pt和Ru的浓度对电极表面组成形貌和电催化活性的影响.实验表明,优化电解液中Ru的浓度,可使电极表面形成分布均匀的纳米级Pt-Ru合金,并表现出良好的电催化性能.采用环境扫描电子显微镜表征电极的表面形貌;采用能谱仪测定Pt-Ru电极的表面组成;采用循环伏安法测量Pt-Ru电极的电化学性能.

关键词: 电沉积 , Pt-Ru电极 , 电解液组成

Ru前驱体对Ru/MgO-CeO2氨合成催化剂性能的影响

王秀云 , 王榕 , 倪军 , 林建新 , 魏可镁

催化学报 doi:10.3724/SP.J.1088.2010.00539

分别以K2RuO4,Ru(Ac)3和RuC13为Ru前驱体,制备了Ru/MgO-CeO2催化剂,并运用X射线衍射、X射线荧光光谱,CO吸附、N2物理吸附和H2程序升温还原等技术对催化剂进行了表征,考察了Ru前驱体对Ru/MgO-CeO2催化剂氨合成性能的影响.结果表明,Ru前驱体对载体MgO-CeO2和Ru的还原件能、氯残留量和催化剂比表面积的影响都很大,从而导致催化剂的氨合成性能的不同.其中以K2RuO4为Ru前驱体制备的催化剂的载体和Ru容易还原,无氯离子,且比表面积较高,因而催化剂活性和氨合成转换频率较高.在10MPa,425℃,10 000h-1条件下,K2RuO4,Ru(Ac)3和RuC13作前驱体制备的催化剂上氨合成转换频率比为1.33:1.05:1.

关键词: 前驱体 , 氨合成 , 氧化镁 , 二氧化铈 , 钌

Fe/Ru界面对多层膜磁性的影响

耿魁伟 , 姚若河

稀有金属材料与工程

采用高分辨透射电镜结合振动样品磁强计研究了Fe/Ru多层膜,对不同层厚的Fe/Ru多层膜的界面结构及其对磁性能的影响进行了分析.Fe层很薄时薄膜不连续,岛状分布的Fe颗粒使多层膜显示超顺磁特性.Fe/Ru界面的高分辨电镜观察发现,界面存在粗糙度的不对称性,它是多层膜中产生正磁阻的重要原因.Fe/Ru多层膜的负磁阻在退火后得到较大的提高,表明Fe/Ru多层膜的负磁阻主要来源于界面的粗糙度.

关键词: Fe/Ru多层膜 , 界面 , 磁性 , 磁阻