Effect of Annealing on Ferroelectric Properties of Nanometre BaTiO3 Ceramics Prepared by High Pressure Sintering Method

Dense nanocrystalline BaTiO3 ceramics with a grain size of 5Onto are prepared under 6 GPa at 1273K using a high pressure sintering method. The sintered bulk is uniform and the relative density is above 97%. We anneal the ceramic samples in oxygen with various temperatures and for the annealing, several broadened peaks can be observed at different times without apparent grain growth. After about 378K（ by dielectric measurements. However, these peaks are very different from those of coarser-grained ceramics. It is indicated that both the elimination of oxygen vacancies and the release of residual stresses caused by high pressure greatly improve the overall ferroelectric properties of BaTiO3 ceramics. The observation of nearly linear polarization hysteresis loop after anneal provides the solid evidence of ferroelectricity in these nano-sized BaTiO3 ceramics. It is believed that the absence of 90° domains and the existence of poor-permittivity nonferroelectric grain boundaries contribute to the slim loop.     

对受激布里渊散射激光进行组束的数值模拟及方案设计

 提出了时间上串行的多路激光脉冲通过受激布里渊散射(SBS)池进行组束的方法,并对其进行了数值模拟研究。利用6束每束能量为45J的KrF激光进行组束, 可获得能量为141.89J,脉宽为670ps的Stokes输出光。根据模拟结果设计出了时间上串行的SBS激光组束的两个方案, 对其进行了讨论。数值模拟还发现在介质的增益系数更大、声子寿命更短的情况下,输出激光脉冲的脉宽可以压缩得更窄。     

色散泵浦对受激布里渊散射反射率的影响

将宽带KrF激光通过棱镜进行色散,在气压约为2×106Pa的SF6介质中进行受激布里渊散射的实验研究.通过与没有经过色散的KrF激光进行对比,得到经过色散后的KrF激光作为泵浦光比没有经过棱镜色散的KrF激光作为泵浦光产生SBS的反射率高.     

模式清洁器的噪声转化与输出场噪声分析

根据三镜腔模式清洁器的反射光场及透射光场的传输特性,推导了反射光场和透射光场中振幅和相位两个正交分量的噪声转化函数,理论证明模式清洁器可以实现半导体激光器振幅噪声和相位噪声的相互转化.搭建三镜腔模式清洁器和自平衡零拍探测实验系统,测量了模式清洁器反射光场和透射光场的振幅噪声谱,实验结果与理论结果一致.根据模式清洁器的噪...     

Hel photoelectron spectroscopic (PES) and quantum chemistry study on the dimeric compound of 2(5H) furanone

The HeI photoelectron (PE) spectra of both 2(5H) furanone and its trans-chair-dimenc-compound (t-c-DFN) are reported.The assignment of the PES bands is made on the basis of band shapes,the PES results of the molecules which have the similar atomic groups,and the restricted Hartree-Fock (RHF) calculations for the molecules studied.From the results of both PES experimental and theoretical calculations,it is proved that the ionization potential (IPs) of the HOMO for the dimenc-compound is lower than that of the HOMO for the monomer.And the total energy computed for the t-c-DFN is the lowest in the four possible configurations of dimeric-compounds of 2(5H) furanone Therefore the synthesis of t-c-DFN is also the easiest.     

甚高频片式电感用材料的研究进展

为适应表面安装技术的发展,片式电感器不断向微型化、复合化、多功能化方向发展。介绍了甚高频片式电感器件及其所用材料的研究现状和发展前景。用氧化物固相反应法及软化学方法(柠檬酸络合法)制备的Co2Z型平面六角晶系铁氧体,在实现低烧后,具备优异的电磁性能,满足高性能的甚高频片式电感材料的要求,填补了甚高频段片式电感材料的空白。     

一种基于多级通讯总线的粮库粮情微机监控系统

本文介绍了一种新型的粮库粮情检测监控管理系统，并着重讨论了用VB通讯控件(MSComm)和数据库访问对象(DAO)方法实现上下位机数据通讯，数据处理等管理功能的一些编程技巧和单片机开发的通讯控制总站采用双CPU结构的设计思想。     

介质参数对受激布里渊散射脉宽压缩的影响

 利用KrF激光和SF₆介质从理论和实验上研究了声子寿命和增益系数等介质参数对SBS脉宽压缩比和能量反射率的影响。理论上采用一维瞬态模型对SBS过程进行数值模拟，考虑了瞬态过程、介质吸收以及泵浦耗空的影响，计算了SBS介质不同参数对脉冲压缩影响的规律。实验表明，在实验参数的变化范围内声子寿命越短、增益系数越小，越有利于脉宽压缩。在0.68MPa下，脉宽压缩比达到8。数值模拟了声子寿命和介质增益系数单独变化时对SBS过程影响的规律，发现在声子寿命和增益系数同时变化时，SBS对泵浦脉冲的压缩有最佳点。     

硅基有机发光微显示像素驱动电路设计

由于微型显示像素面积的限制,硅基有机发光微显示像素驱动电路需要实现足够小的驱动电流.文章提出的三管电压控制型像素驱动电路与常规的采用电流镜电路的电流控制型像素驱动电路都能实现微显示所需的小电流驱动.利用Synopsys公司的H-spice软件对两种电路仿真比较,发现电流控制型电路具有线性灰度和较宽的有效灰度范围,但是通过调整电压控制型电路中与OLED并联的晶体管的宽长比,即可使其有效灰度范围与电流控制型电路可比.同时也发现电流控制型电路的功耗是电压控制型电路的4倍以上,且电路形式较复杂,工艺要求较高.所以三管电压控制型电路更适合于硅基有机发光微显示驱动电路.