关键词： 锂离子电池   正极材料   Li1+xCoO2   Rietveld法   微结构   钴酸锂   无机非金屑材料  

摘要： 采用Rietveld分析法研究Li1 +xCoO2 正极活性材料的微结构信息。结果表明 ,合成过程中 ,Li/Co比对钴酸锂正极材料的C轴取向生长有重要影响 ,C轴的取向度可解释 ( 0 0 6)衍射强度的规律变化。通过调整原子坐标位置参数和占有率 ,可解释 ( 0 0 3 )和 ( 10 4)

关键词： 强场   飞秒激光   多光子反应   微结构改性   光功能   光存储   精细加工   材料  

摘要： 飞秒激光是近年来获得迅速发展的一种超快激光 .超短脉冲和超高电场强度是它的两个特征 .飞秒激光已广泛用于物理化学反应的动力学过程分析和热效应可忽略的超精细加工 .利用飞秒激光与材料的非线性相互作用 ,还可以实现透明材料内部有空间选择性的三维调控光功能微结构 .文章重点介绍了在可擦重写三维超高密度光存储、立体彩色内雕、可集成超快光开关等方面的应用和国内外相关领域的最新进展 。

关键词： Ion implantation  

摘要： Thin separation by implanted oxygen substrates are attractive candidates for low-power, low-voltage electronic devices and can be obtained by low-dose, low-energy oxygen-ion implantation. We report in this study a variation of the process parameters that have never been investigated before, particularly for implantation with a high current density implanter. Characterization of the sample sets by transmission electron microscopy, secondary ion mass spectroscopy (SIMS), and Rutherford backscattering spectrometry (RBS) shows an optimum dose of 3.0 to 3.5 x 10(17) O+/cm(2) at 100 keV for forming, a continuous buried oxide (BOX) layer compared to 2.5 x 10(17) O+/cm(2) at 65 keV. At this optimum condition for 100 keV, the thickness of Si top layers and BOX layers is in the range of 175-185 nm and 70-80 nm, respectively. Analysis of the breakdown voltage of small area capacitors shows a breakdown field in the range of 6.0-7.0 MV/cm, which is adequate for low-power, low-voltage devices. SIMS analysis shows that the maximum oxygen concentration of as-implanted samples is located at depths of 160 and 240 nm for the implantation energy of 65 and 100 keV, respectively. A significant redistribution of oxygen occurs at temperatures above 1300 degreesC during the ramping process. RBS analysis showed that a high-quality crystalline Si layer was produced after annealing at 1350 degreesC for 4 h. The defect density determined by the chemical etching method was found to be very low (<300 defects per cm(2)) for all samples with a dose range of 3.0 x 10(17) O+/cm(2) to 6.0 x 10(17) O+/cm(2) implanted at 100 keV. However, a 65 keV sample with a dose of 4.5 x 1017 O+/cm(2) contains about 109 defects per cm(2). The larger defect density in the 65-keV sample may be due to the shift of oxygen depth distribution toward the surface, resulting in easier defect extension during, the annealing process. The oxide precipitates in the Si overlayer play a key role in defect reduction by blocking the

关键词： 原位   TiB2   TiC   铁基复合材料   微结构  

摘要： 热力学分析表明,Fe Ti B C熔体具有反应生成TiB2和TiC的可能性,TiB2和TiC热力学稳定性相当。试验结果表明,利用Fe Ti B C熔体反应可以制备TiB2和TiC颗粒增强铁基复合材料,TiB2颗粒和TiC颗粒均匀分布于α Fe晶粒中,TiB2颗粒比TiC颗粒具有更大的平均尺寸。

关键词： 溶胶-凝胶法   生物活性玻璃   生理溶液   碳酸羟基磷灰石   扫描电子显微镜   X射线衍射   红外光谱分析   材料结构  

摘要： 本文利用溶胶 凝胶法制备了CaO P2 O5 SiO2 系统生物活性玻璃 ,并以其为原料制备了用于骨修复及骨组织工程支架的块状生物活性材料。利用体外实验方法 (invitro)结合X射线衍射 (XRD)、扫描电子显微镜 (SEM)和傅立叶变换红外光谱分析 (FTIR)技术对不同烧结工艺制备的材料结构、晶相和生物活性的影响进行了分析研究。研究表明 ,经 80 0℃和 110 0℃烧结 5min的两种材料均有硅磷酸钙Ca5(PO4 ) 2 SiO4 微晶相析出。烧结温度越高 ,析出微晶相的体积比例越大 ,材料的生物活性则越低。在模拟生理溶液中碳酸羟基磷灰石 (HCA)只在烧结体中的玻璃颗粒表面形成 ,而在其硅磷酸钙Ca5(PO4 ) 2 SiO4 微晶相表面未发现HCA形成。

关键词： nonlinear optics   optical fiber communication   optical fiber devices   optical parametric oscillators   optical pulse generation   supercontinuum generation (SCG)  

摘要： We demonstrate a microstructure-fiber (MF)-based supercontinuum source and a synchronously pumped optical parametric oscillator in the 1550-nm regime. By using a 12.5-m-long MF, we obtained a 10-GHz repetition-rate picosecond-pulse source that is capable of similar to120-nm wavelength tunability due to the wide-gain bandwidth of the combined processes of stimulated Raman scattering and parametric four-wave mixing.

关键词： hot pressing   mechanical properties   microstructure-final   pressureless sintering   sialons  

摘要： The microstructural development of Ca alpha-sialon ceramics has been studied. It was found that the microstructure of these materials could be controlled by the starting compositions and the processing conditions. Consequently, the observed microstructure has been related to the mechanical properties of these materials. It was found that although fracture toughness increased with increasing grain size and aspect ratio, a weakened interface between the alpha-sialon grains and intergranular glass is essential to further improve the toughness of these materials. (C) 2003 Elsevier Science Ltd. All rights reserved.

关键词： Keggin结构   稳定性   无机插层柱撑蒙脱石   功能材料   微结构  

摘要： 使用含Al3+ 的Keggen离子制备了无机插层柱撑蒙脱石 ,并运用2 7Al核磁共振谱等技术对柱化溶液中的Al的状态进行了研究 ,运用X射线定向衍射技术、红外光谱、差热、热重分析及原子力显微镜等技术对柱化黏土中Keggin结构的作用及热稳定性进行了研究。结果表明 ,AlCl3溶液在 [OH- ] /[Al3+ ] =2 .4时水解生成的Keggin离子最多。柱撑蒙脱石层间距在自然状态下为 2 .53nm ,30 0℃灼烧后层间距稳定在 1 .83nm 。

关键词： 羟基磷灰石   电沉积-水热合成   生物陶瓷   涂层  

摘要： 研究了低钙磷比溶液电沉积缺钙羟基磷灰石生物陶瓷涂层在水热合成和700℃,800℃,900℃焙烧后的相组成和显微组织结构;用扫描电镜(SEM)、X射线衍射(XRD)和透射电镜(TEM)对涂层进行分析。结果表明:在电沉积液Ca/P比1.30,沉积液温度25℃,电压4V条件下,Ti基体表面沉积了片状和条状HAP和CaHPO4·2H2O混合相涂层;在pH值为12的碱液中,150℃和200℃水热合成4h后涂层由针状纯HAP组成,Ca/P比约为1.61,且随着水热合成温度的升高,晶体结晶度提高,但晶体无明显长大趋势;700℃焙烧后,涂层仍由纯HAP组成,只是晶体因失水而发生团聚;800℃焙烧后,部分HAP发生分解,生成β-Ca3(PO4)2,且HAP与β-Ca3(PO4)2的体积比为90∶10,形貌为块状和板条状,其表面附着许多细小的针状颗粒;900℃焙烧后,β-Ca3(PO4)2的含量增加,HAP与β-Ca3(PO4)2的体积比为74∶26,小颗粒团聚成较大的块状和板条状颗粒。由此制备了对骨组织生长更有利的HAP+β-Ca3(PO4)2双相涂层结构。

关键词： 介电体超晶格   三基色   光学超晶格结构   非周期结构  

摘要： 本论文主要总结了我在南京大学介电体超晶格实验室(DielectricSuperLatticeLaboratory)近两年的研究工作中的一些初步进展和结论。主要囊括了以下几方面的内容：\n 1.较为系统的阐述基于准位相匹配(QPM)原理的介电体光学超晶格的设计方法。主要在理论上探讨如何设计各类非周期结构的介电体超晶格用以实现耦合的级联光学参量过程。\n 2.将讨论延伸到在2D上，利用复式结构以及构造方法设计实现用以耦合级联光学参量过程的QPM结构。\n 3.采用了两类方案，分别用三组元准周期结构和构造方法设计了用于实现同时三基色输出的光学超晶格结构。其中两个方案分别设计为采用了双红外泵浦源和单一的红外泵浦源通过超晶格实现三基色输出。\n 4.