正庚烷在β沸石负载碳化钼催化剂上的异构化研究

利用程序升温还原法制备了β沸石负载碳化钼催化剂。XRD表征显示，利用正戊烷作为碳源得到了对异构化具有活性的βMo2C。以正庚烷为模型反应物，在连续流动固定床反应装置上考察了温度、压力、空速和氢烃比对βMo2C/β沸石催化剂临氢异构化反应性能的影响。获得了β沸石负载碳化钼催化剂上正庚烷异构化的最佳反应条件温度270℃～275℃，压力1.0MPa～1.5MPa，体积空速1.0h－1，氢烃体积比200∶1。在最佳条件下反应物转化率为82%，选择性和异构产物收率分别达到71%和58%。     

表面弛豫效应对界面区域CBED的影响

对Al_2O_3颗粒增强铝复合材料与K_2Ti_5O_(13)晶须增强铝复合材料中的增强相/金属界面区域点阵位移场进行CBED研究,并对其进行电子衍射动力学理论模拟计算,结果表明:表面弛豫效应对晶须/铝界面法线方向上位移分量大小的分布影响显著,而对界面切线方向上位移分量的影响很小。这一结果对于解决CBED法测量界面应变场时遇到的表面弛豫效应问题是有意义的。     

Fe3O4 Segregation and Transport Properties of La0.67Ca0.33MnO3

Effect of Fe3O4 segregation at grain boundaries on the electrical transport and magnetic properties of La0.67Ca0.33MnO3 is investigated. The experimental results show that the Fe3O4 segregation not only shifts the paramagnetic-ferromagnetic transition temperature of La0.6TCa0.33MnO3 to a lower temperature region but also induces a new transition in a lower temperature region. Meanwhile, the transition processes observed in both the resistivity and magnetization curves are obviously widened. Compared to pure La0.67Ca0.33MnO3, we assume that the Fe3O4 segregation level at the grain boundaries can modify the electrical transport and magnetic properties of La0.67Ca0.33MnO3.     

一种大容量动力锂电池的化成系统

随着新能源技术的发展,对大容量的动力锂电池需求越来越多,尤其在电动汽车领域具有广泛的使用;为此设计了一种适用于大容量锂电池的化成系统,说明了其组成和工作原理;为了提高充放电过程中电流控制的精度,采用了可编程反馈式限压恒流斩波控制电路,同时具有限压保护功能,防止锂电池过充过放;化成系统为上下位机结构,由一台上位机(服务器)和若干台下位机(化成单元)组成,组成工业485总线网络,利用上位机对化成过程进行实时监控和数据记录;经试验测试,该系统具有充放电电流大、控制精度高、可多工步编程等特点,能够满足动力锂电池大规模化成生产的需要。     

Three-dimensional size and orientation of the precipitates in AZ91 magnesium alloys measured by TEM techniques

Knowledge of the microscopic structure, including three-dimensional (3-D) size and orientation of the precipitates, is essential to fully understand the mechanical properties of the magnesium alloys and designing the alloys with better performance. Analytical TEM with high spatial resolution offers the simultaneous measurements of 3-D size, structure, orientation, composition of the precipitates from one typical sample along an established crystallographic axis. Besides popular Burgers orientation relationship (OR), other ORs such as Pitsch--Schrader OR, Crawley OR, Potter OR and a new OR with the form of [0001]_α 1.0° from [311]_γ and (11\bar 20)_α 2.0° from (03\bar 3)_γ between the magnesium matrix and the precipitate γ -Mg₁₇Al₁₂ are identified by TEM imaging and diffraction techniques. As a case study, the thicknesses of the individual precipitates with Burgers OR are further measured to be 100--200~nm through both electron energy-loss spectroscopy and x-ray energy dispersive spectroscopy combining differential x-ray absorption and extrapolation, which are in agreement with the overall 3-D size statistic distribution results obtained through analysing various samples along various directions. Furthermore, the fabricated wedge-shape structure provides a platform on which to study the dependence of the interfacial strain on the variation of the thickness.     

尖晶石锂锰氧化物中氧缺陷对材料电化学性能的影响

研究了富锂锂锰氧化物中氧缺陷对材料电化学性能的影响。X射线衍射谱表明有氧缺陷的锂锰氧化物仍可保持尖晶石结构，当氧缺陷浓度达到一定程度时，高角度区的衍射峰出现分裂，说明其微观结构发生了变化。充放电实验结果表明氧缺陷使4V区的锂离子嵌脱变成了多步，模拟电池的容量微分曲线有3对清晰的氧化还原峰，低电位的氧化还原峰被—分为二。氧缺陷降低了材料的放电容量，同时引起低电位区的放电容量向更低电位区转移，使电化学性能恶化，锂锰氧化物中氧缺陷对电化学性能的影响对此类材料的合成提供了理论和实践依据。     

准晶的弹性,塑性与位错

本文较系统地综述了适合准晶的线弹性理论，准品位错的基本理论和实验鉴定，准晶位错的弹性理论，以及准晶高温塑性形变的微观机制。     

晶粒取向和物相组成的电子背散射衍射测定

介绍了用扫描电镜中电子背散射衍射（ＥＢＳＤ）附件所进行的初步研究工作．这些工作表明,２Ｈ马氏体的基面由母相的一个｛２２０｝Ｐ面转变而来,一个自协作马氏体片群内的Ａ、Ｂ、Ｃ、Ｄ４个变体由母相的不同的｛１１０｝Ｐ面转变而来．用ＥＢＳＤ技术可测出它们之间的取向关系．ＥＢＳＤ技术所提供的结构信息与Ｘ射线能谱分析提供的化学成分信息相结合使微区物相鉴定的结果更为可靠．发现Ａｌ６２．５Ｃｕ２５Ｆｅ１２．５合金的铸态主要由λ－Ａｌ１３Ｆｅ４、二十面体准晶和β相３者组成．无间隙钢７５０℃再结晶后有两类晶粒,其中平坦晶粒具有有利于冷加工性的γ纤维显微织构．     

Experimental Observation on Orientation Relationship between Binary Cd5.7Yb Quasicrystal and its Crystalline Approximant Cd6Yb

Similarity in the electron diffraction patterns of the Cd5.7 Yb icosahedral quasicrystal and its cubic approximant Cd6 Yb crystal is studied in detail by using transmission electron microscopy. The icosahedral twofold axes are parallel to the cubic （1ττ^2） （τ= 1.618…） or （0 0 1） directions, the icosahedral pseudo-twofold axes are parallel to the cubic （15 21 25） directions, the icosahedral threefold axes are parallel to the cubic 〈1 1 1〉 and the icosahedral fivefold are parallel to the cubic 〈0 1 τ〉 directions. Based on those observations a general stereographic projection is given to illustrate the exact orientation relationship.     

轻元素K_α射线的质量吸收系数

本文简要评述轻元素(从 Be 到 F)K_α射线质量吸收系数的测定方法,即透射衰减法、等价膜厚法。吸收修正计算法、最有利电压法和全反射法,并将近十余年较有参考价值的测量或内插所得数据收集整理列成附表。