ZnO纳米棒阵列在TiO2介孔薄膜上的生长及其表征

通过低温水热法成功地将ZnO纳米棒阵列定向生长在了介孔锐钛矿TiO2纳米晶薄膜上,并主要利用X射线衍射、场发射扫描电子显微镜和光致发光光谱等对其进行了表征。所制备的纳米棒具有六边形的端面,纳米棒的尺寸及端面边长分布范围窄,并且沿c轴方向(002)表现出了明显的择优化生长。此外,相比于玻璃基底或TiO2纳米颗粒薄膜,生长在介孔TiO2薄膜上的ZnO纳米棒阵列表现出了较好的取向生长,表明基底的表面结构和组成对ZnO纳米棒阵列的生长有显著的影响。根据基底有序的多孔结构,讨论了纳米棒阵列可能的生长机理。所得到的ZnO纳米棒阵列在室温下分别表现出了以370 nm为中心的强近紫外光和以530 nm为中心的弱绿光两条荧光谱带。     

三角形的一个向量性质及其空间拓广

文[1]、文[2]、文[3]及文[4]对一个三角形重心向量性质进行了探讨，笔者阅读后深受启发，得到了三角形的一个向量性质，并进行空间拓广．     

动载荷下弹塑性随动强化结构的安定问题

本文讨论了弹塑性随动强化结构的动力安定问题,其加载面在应力空间中是任意形状的凸曲面。文中给出了相应的安定定理,指出如果能找到任何一个与时间无关的和虚设残余应力而使结构安定,则该结构将一定是动力安定的。此外,本文还给出了塑性功和塑性应变的上界估计式,并以在交变载荷作用下的Mises随动强化材料的简支圆板为例,对定理的应用进行了说明。     

国际离子交换会议(ICIE’91)在日本举行

1991年10月2-4日在日本东京工业大学(TIT)国际会议厅举行了国际离子交换学术会议ICIE′91。会议由日本离子交换协会(JAIE)发起,由13个学会支持,并得到日本30多家公司的资助。日本TIT理学部化学系阿部光雄教授为会议主席。出席会议人数为213人,来自世界24个国家和地区。我国学者天津大学姜志新、兰州大学陶祖贻、国家局第二海洋研究所莫     

4,4‘—二苯醚二甲酸的新合成路线

4,4′-二苯醚二甲酸(以下简称醚酸)是一种重要的高聚物单体,用于制备合成树脂、绝缘材料和液晶纤维等,在国防工业和民用工业上有着宽广的前途。但国内至今尚无醚酸产品。醚酸的合成路线归纳起来有两大类:一类是以4,4′-二甲基二苯醚为原料,将甲基氧化成羧基。另一类是以二苯醚为原料,接上相应的基团,再转化成羧基。二苯醚类则由酚和卤苯经 Ullmann 缩合反应制得。由于反应需要200℃以上的高温,长时间加热,因而产品质量     

A STUDY ON SECONDARY DEFECTS IN SELF-ION IMPLANTED Si

By using the cross-sectional transmission electron microscopy (XTEM), Rutherford backscattering (and channeling) spectrometry (RBS) and high-energy electron beam irra-diation technology with a high voltage electron microscope (HVEM), secondary defects in self-ion implanted Si has been studied. The result shows that the depths of secondary de-fect bands are related to the implantation energies, and the values of depths are slightly greater than the projected ranges of self-ions implanted into Si. In the higher energy region (>1MeV), the former exceeds the latter by nearly 0.2-0.4μm. Experiments indicate that the pre-implantation damage (the primary defect), on one hand, will superpose on the primary defects of post-implantations and make secondary defects increase, and on the other hand, it will also provide an enhanced-diffusion region for vacancies and interstitials created by the post-implantation and reduce the formation of secondary defects. Experiments also show that dislocation loops in secondary defect bands of self-implanted Si are interstitial in nature.     

Gas Sensor Using a Robust Approach under Time Multiplexing Scheme with a Twin Laser Chip for Absorption and Reference

A tunable diode laser absorption spectroscopy nitrous oxide gas sensor at 2.1 micrometres using one antimonide twin laser chip and one InGaAs photodiode is demonstrated, in which time multiplexing techniques are adopted to acquiring both the absorption and reference signal in a robust fluctuation tolerable scheme. Electronics in analogue modality is developed to extracting absorption information and compensating for fluctuations, resulting in a direct analogue voltage output corresponding to the target gas concentration in real time. The performance of the gas sensor is evaluated experimentally, the validity and feasibility of this scheme is also discussed.     

半结晶聚酯(PET)的二相共存结构的表征

采用X射线衍射对称反射法,对半结晶聚酯PET₂试样收集粉末X射线衍射全图(XDWP)数据,用Rietveld方法和Fourier过滤技术,对XDWP拟合并分离成结晶衍射峰之和CR₂和非晶散射峰之和AM₂两部分,与此同时获得PET₂试样的结晶相CR₂的三斜晶系晶胞参数:a=0.445,b=0.592,c=1.072nm,α=99.6,β=116.9,γ=111.9(°),结晶密度d_{c关键词： 聚对苯二甲酸乙二醇酯 二相共存结构 径向分布函数 Rietveld方法 Fourier过滤技术}