关键词： SnO2纳米晶   掺杂   结构表征   光学性能  

摘要： 以二价SnCl2 无机盐为原料 ,基于配合物前躯体方法制备了氧化锡及铜离子掺杂氧化锡纳米晶 .根据DSC和TG分析结果在 5 5 0℃对前驱体进行煅烧 .运用FTIR、UV -VIS、XRD和TEM HRTEM等测试手段对两纳米晶材料进行了分析表征 .掺杂后掺杂相氧化物分散驻留在SnO2 晶粒表面 ,阻止了SnO2 晶粒表面的扩散 ,从而抑制其晶粒生长 .此外 ,铜离子掺杂使得表面缺陷附近的自由电子能有效的定域化 ,从而使SnO2 纳米晶体系的直接和间接带隙能均向高能方向移动 .试验证明以无机盐代替金属醇盐为原料是切实可行的 ,且配合物前躯体法简单易操作 。

摘要： The review considers characteristic features of the crystal structure, phase relations, microstructure and physical properties of the most important classes of modern cuprate and manganite materials including high-temperature superconductors, CMR magnetic semiconductors and superionic conductors. The bibliography includes 189 references. © 2004 Russian Academy of Sciences and Turpion Ltd.

关键词： multilayer ceramic capacitors   barium titanate zirconate   re-oxidation   dielectric properties   temperature dependence   microstructure   donor   acceptor   TEM-EDS   EXAFS   XANES   ESR  

摘要： The influence of the microstructural evolution induced by increasing firing temperature on the change in dielectric properties induced by re-oxidation treatment in the Ba(Ti, Zr)O-3(BTZ)-Ho-Mn system was investigated. The microstructural observation of as-fired disk samples revealed gradual grain growth with firing temperature. From the temperature characteristic (TC) measurement, the shift to higher temperatures of dielectric maximum (T-max) due to re-oxidation treatment became larger with grain growth although the chemical compositions were quite the same. It was found that grain growth accelerated the valence change of Mn by re-oxidation treatment and the substitution of dopants in a grain in this system. Microstructural evolutions, such as compositional distribution and the concentration of additives in a grain, had an influence on the changes in dielectric properties induced by re-oxidation treatment.

关键词： laser processing   Al2O3-ZrO2-SiO2 refractory   solidification   phase and microstructure   selected evaporation  

摘要： In this study, an Al2O3-ZrO2-SiO2 system refractory with the alumina-mullite-zirconia (A-M-Z) structure was treated by CO2 laser surface melting aiming at improving its surface density and modifying the corresponding microstructure, which were considered to be important factors influencing the erosion resistance of refractory materials. The microstructure and phase structure features of the refractory induced by the laser beam have been investigated by scanning transmission microscopy incorporating energy dispersive X-ray technique and X-ray diffraction analysis. After laser surface melting, the microstructure was changed into a fine and dense dendrite structure in the top and center region of the laser-melted zone and the non-dendrite structure between a dendrite region and the substrate region. The phase M-ZrO2 or c-ZrO2 was uniformly dispersed into the dendrite instead of the non-uniform particle-like shape in the as-received refractory, and the dominant phases were changed from alpha-Al2O3 + Al6Si2O13 to m-ZrO2 + alpha-Al2O3 + Al2.427O3.64 due to the selected evaporation of constituents SiO2 and Al2O3. (C) 2004 Elsevier B.V. All rights reserved.

关键词： C1000   D0100   F0400   I0400  

摘要： The effects of aging and ion irradiation on microstructure stability and hardness change in the joint materials of CuNiBe/316L and CuAl25/316L have been investigated in the present study, The aging at 673 K for 1000 h or Ni ion irradiation at 573 and 673 K to 10 dpa did not promote the interdiffusion and void swelling at the interface. The hardness in both Cu alloys and stainless steel was increased by irradiation, however, it was decreased by aging except for CuNiBe alloy. The hardness change in CuNiBe alloy was larger than that in CuAl25 alloy. The hardness changes would have a significant effect on the mechanical properties of joint materials. (C) 2004 Elsevier B.V. All rights reserved.

关键词： 刻划   衍射   飞秒激光   表面   光参数   微结构   PMMA   光栅   线宽   色散  

摘要： 使用振荡器产生的飞秒激光在透明有机材料PMMA表面进行了刻划微结构光栅的研究.通过理论分析得 到了飞秒激光参数和平台移动速度对线宽的影响,进行了系统的加工实验,加工结果与理论分析基本吻合.在透明有机材料PMMA表面进行了多种光栅的刻划,并对刻划的光栅进行了衍射和色散测试,调整光栅的尺寸和排列方式,得到了形状各异的衍射图案.

关键词： 低压等离子喷涂法   WC-Co纳米涂层   显微结构   扫描电子显微镜分析   X射线衍射分析  

摘要： 本研究采用低压等离子喷涂制备WC-Co纳米涂层,利用SEM、XRD等手段研究真空状态下形成的WC-Co纳米涂层的显微形貌和结构.

关键词： M0500   S0400   V0200  

摘要： The microstructural development of SiC/SiC composite under the multi-ion beam irradiation up to 10 dpa at 800 and 1000 degreesC was investigated by transmission electron microscopy. Microstructural evolution in each composites component was dependent on the component grain structures, the helium or hydrogen implanting mode and the irradiation temperature. In this study, the synergistic effects of H and He gas elements on cavity formation in the composite component are discussed. (C) 2004 Elsevier B.V. All rights reserved.

关键词： 红柱石骨料   SiC   碳化硅   烧成温度   莫来石-堇青石陶瓷窑具   显微结构   物理性能   烧结性能  

摘要： 研究了红柱石骨料的莫来石化作用及添加剂SiC的加入量、合成莫来石的引入和烧成温度对莫来石-堇青石窑具材料性能及显微结构的影响。结果表明 ,在 1380℃ 4h下烧成时 ,红柱石的莫来石化作用能大大改善材料的烧结性能 ;加入 4 %的SiC可提高材料的物理性能 ;部分合成莫来石的加入可克服红柱石在莫来石化过程中的不足 ,强化材料的组织结构 。

关键词： sliding wear behaviour   stellite   surface modification   microstructure-wear property correlation  

摘要： This investigation deals with the influence of hardfacing En31 steel separately with Fe - TiC composite and commercial cobalt base ( stellite 6) material on their sliding wear behaviour at 2.94 m/ s speed and varying applied pressures. Wear response of the samples was substantiated through the scanning electron microscopic studies of the wear surfaces, subsurface regions and debris particles. The hardfaced samples revealed superior wear performance than that of the substrate. Further, the steel hardfaced with cobalt- based stellite offered higher wear resistance over the one overlayed with Fe - TiC composite. The applied pressure controlled the wear behaviour ( rate) in a complex manner and its influence was dependent on material composition/ microconstituents and test conditions. The friction coefficient got reduced with pressure except in the case of the Fe - TiC composite overlay beyond 2 MPa. The hardfaced samples were noted to be better suited for more severe conditions. Microcracking was quite frequently observed on wear surfaces of the hardfaced material especially under mild wear conditions. Sticking of fine debris particles on to the specimen surface was also observed.