十四烷基三甲基溴化铵对膨润土改性合成及其表征

用阳离子表面活性剂十四烷基三甲基溴化铵(C17H38NBr)对膨润土进行插层改性制备.配制浓度为2.35%十四烷基三甲基溴化铵溶液备用.在碘量瓶中称取3.04g膨润土,加入30mL超纯水、10mL十四烷基三甲基溴化铵溶液,制成土浆,放入微波炉中反应1min.产物经抽滤、洗涤、烘干、研磨,做FT-IR和DSC-TG分析.DSC曲线在500℃时有一明显的放热峰;TG曲线显示改性土的失重率有明显的增大.有机改性膨润土中确实含有大量有机物,改性成功.     

Ge_x Si_(1-x)/Si超晶格中纵声学声子的喇曼散射强度研究

本文用光弹理论,在全面考虑了超晶格中两种材料的声速,质量密度和光弹常数存在差别的基础上,计算了Ge_xSi_(1-x)/Si超晶格中折迭纵声学声子的喇曼散射强度,在高达50cm~(-1)的频率范围内,理论值和实验符合得很好。     

高能物理学发展的回顾和展望

 从电弱统一理论提出到现在已经过去了23年.量子色动力学从诞生到现在也已经历了17年,在这期间CERN建成了E_cm=60GeV的质子对撞机ISR;FNAL和CERN分别建成了能量为500GeV和450GeV的质子同步加速器.     

Pseudo-Spin-Valve Trilayer Using Amorphous CoNbZr Layer： Giant Magnetoresistance, Domain Structures and Potentials for Spin-Electronic Devices

We propose a pseudo-spin-valve (PSV) trilayer using amorphous CoNbZr Mloy for soft magnetic layers. The giant magnetoresistance (GMR), domain structures and their variation upon thermal annealing are investigated. The GMR effect is not only stable up to 300℃ but also enhanced due to the improvement of the interfaces between Cu and magnetic layers. With high annealing temperature, the magnetoresistance (MR) ratio decreases rapidly as a result of serious layer interdiffusion. Dense stripe domains, which disappear after annealing at 300℃ for 1h, are observed in the sandwiched films. It is found that after patterning to elliptic stripe with aspect ratio of 6:1, the trilayers have a single domain and their MR ratio increases. The dynamic MR behaviour under an ac magnetic field indicates that the patterned stripes have good linear MR responses. Therefore, it is believed that the CoNbZr/Cu/Co PSV trilayers have strong potentials for spin-electronic devices including magnetic random access memory.     

端面泵浦掺Yb3+双包层光纤激光器

从双包层光纤激光器的速率方程出发，得到了光纤中泵浦光与激光的功率分布、输出功率与泵浦功率的关系、腔镜反射率及光纤长度对输出功率的影响。研究结果表明：输出激光功率与光纤长度及后腔镜反射率有很强的依赖关系，存在一个输出功率最大的最佳光纤长度。后腔镜反射率越大，输出激光功率越小；当光纤长度较短时，在输出端放置反射镜使泵浦光高反射，可以提高输出功率和效率。通过对端面泵浦掺Yb3+双包层光纤激光器进行理论分析和实验研究，得到输出激光的中心波长为1088.3nm，斜率效率为33.7%，最大输出功率为1.75W。     

Reduction of Dislocations in GaN Epilayer Grown on Si （111） Substrates using a GaN Intermedial Layer

GaN intermedial layers grown under different pressures are inserted between GaN epilayers and AIN/Si（111） substrates. In situ optical reflectivity measurements show that a transition from the three-dimensional （3D） mode to the 2I） one occurs during the GaN epilayer growth when a higher growth pressure is used during the preceding GaN intermedial layer growth, and an improvement of the crystalline quality of GaN epilayer will be made. Combining the in situ reflectivity and transmission electron microscopy （TEM） measurements, it is suggested that the lateral growth at the transition of growth mode is favourable for bending of dislocation lines, thus reducing the density of threading dislocations in the epilayer.     

Al2O3SiO2/ZL109 金属基复合材料的强度性能研究

介绍了硅酸铝短纤维增强ＺＬ１０９铸铝合金（Ａｌ２Ｏ３ＳｉＯ２／ＺＬ１０９ＭＭＣ）的静态实验和冲击实验结果。给出了这种复合材料的静态强度、动态屈服强度和层裂强度并对实验结果进行了分析讨论。     

单层光学薄膜中薄膜－衬底体系的双重干涉效应及其应用

提出了单层光学薄膜中薄膜与衬底反射光之间的双重干涉效应的理论，实验结果证实了理论分析的正确性。双重干涉效应使薄膜－衬底体系的热致反射调制度高达８０％，这一效应可望有极广泛的应用