Ti 离子注入 LiNbO_3表面损伤分析

本文分析了高能 Ti 离子注入 LiNbO_3后 x,y,z 三种不同切向的表面损伤分布及退火效应。x,y 切片表面损伤程度近乎无定形,Nb 原子迁移率 N_D/N=1;z 切片表面损伤仍未饱和,N_D/N=0.8。辐射损伤主要是大量 Nb 偏离晶格位置成为间隙原子,注入的 Ti 离子处于间隙位置—LiNbO_3结构中固有的空位,使晶格有微小的膨胀。注入后产生有大量的氧缺位,氧气氛中热退火可消除氧缺位,使位移原子恢复至原晶格位置,且大部分间隙位置上的 Ti 离子通过替代 Nb 或少数 Li 进入正规格点上,此处晶格有少许收缩;热处理后损伤的消除由注入层与衬底的界面处向外表面方向进行,需1000℃高温退火,晶格损伤才能获得明显的改善,氧气氛可防止氧缺位的增多。     

富锂LiNbO_3∶Fe∶Mg晶体中的X射线折变

从双折率变化测量、吸收光谱和 ESR 谱三个方面研究了富锂 LiNbO_3∶Fe∶Mg、LiNbO_3∶Fe 和纯的LiNbO_3晶体中 X 射线致折射率变化。结果表明 X 射线致折射率变化现象不同于通常的光折变。伴随着 X射线折变的产生,出现了光色效应。X 射线折变后,晶体中 Fe~(2 )含量增加。X 射线折变可能是过量的 Fe~(2 )产生的。     

掺镁铌酸锂晶体——一种新的光电多功能集成晶体材料

铌酸锂(LiNbO_3)晶体是制作电光、非线性光学和集成光学器件的最重要的晶体材料之一。在光学应用中遇到的最大问题是容易产生光致折射率变化(光折变),引起光波前畸变,限制了其在高激光功率下应用。为了提高其抗光折变性能,以前多采用减少杂质的纯化方法,但效果不大。1980年我国     

新型GYSGG(GdxY3-xSc2Ga3O12)晶体的生长、结构及透过光谱研究

采用提拉法成功生长出高质量的GYSGG(Gd_0.63Y_2.37Sc₂Ga₃O₁₂)晶体, 对其结构及透过光谱进行了研究。GYSGG晶体的晶格常数大于目前常用的GGG 和CaMgZr:GGG,介于YSGG与GSGG之间。可通过改变晶体中Gd与Y的比例, 获得应用中所需不同晶格常数的晶体基片。另外, 晶体三个结晶面的摇摆曲线有对称的形状和较小的半高宽, 表明晶体有较好的结晶完整性。观察分析了晶体三个结晶面的位错腐蚀图。透过光谱分析表明晶体有宽的透光波段, 将计算得到的折射率曲线拟合得到了折射率塞米尔方程系数。因此, GYSGG不仅是一种优良的激光基质晶体, 也是一种宽波段窗口材料和潜在的具有较大晶格常数, 并且晶格常数可调的新型磁泡应用衬底材料。     

Ti~(4+)对PbZrO_3和Pb(Zr_(1-x)Ti_x)O_3粉体晶格结构的影响

研究了Ti4+离子对PbZrO3和Pb(Zr1-xTix)O3粉体晶格结构的影响。利用固相反应法合成的PbZrO3和Pb(Zr0.95Ti0.05)O3粉体,从XRD、晶格常数和Raman光谱3个方面进行了分析。结果表明:PbZrO3和Pb(Zr0.95Ti0.05)O3均为钙钛矿结构,但较之PbZrO3,Pb(Zr0.95Ti0.05)O3的XRD谱各个峰位均向高角度轻微偏移;晶胞参数变小;Pb(Zr0.95Ti0.05)O3的Raman峰除在低频区向低频方向发生了偏移,而其余峰均向高频方向发生了偏移且部分峰有宽化现象。主要是由于Ti4+离子部分取代Zr4+离子进入PbZrO3晶格而形成Pb(Zr1-xTix)结构。     

环向切缝药包爆破块度分布特征及其机理研究

为研究环向聚能作用对爆破块度的改善效果,采用标准混凝土试块开展了环向切缝药包爆破与常规爆破试验。对两种不同爆破方式得出的爆破块度进行了筛分统计,试验结果表明：相同装药量下环向切缝药包爆破得到的平均块度和大块率较低;与常规爆破相比,环向切缝药包爆破平均块度可降低2～15 mm,大块率可减少0.66%～30.74%。针对环向切缝药包爆破时,其减小平均块度的程度随装药量的增加出现先增加后降低现象,选取3种典型药量(4、10和14 g)构建了数值模型进行裂纹扩展特征分析,对比了切缝药包爆破时切缝处孔壁爆破压力与常规爆破时相应位置的爆破压力。结果表明：常规爆破时孔壁裂纹均匀向外发展,且裂纹长度基本相同;环向切缝药包起爆后,在切缝与非切缝交界处先形成裂纹并扩展,其他位置的裂纹后形成且长度较短。对切缝处孔壁的爆破压力进行模拟分析,结果表明：3种不同药量情况下环向切缝药包与常规爆破的压力峰值之差分别为0.62、1.25和0.41 GPa,从应力分布角度解释了环向切缝药包可通过改变爆破能量在被爆体内的分布规律进而降低爆破块度的作用机理。     

低损耗、高消光比的Z切钛扩散铌酸锂调制器

为了获得低损耗、高消光比的光波导电光调制器,以钛扩散铌酸锂( Ti: LiNbO3 )波导折射率的分布和光波导的优化设计为基础,利用有限差分光束传播法( FD-BPM )和点匹配法,从理论上给出了一种光损耗为-0.53dB、消光比为30dB的Z切钛扩散铌酸锂调制器。并且,在10Gbit/s的系统中对其进行了测试,取得了在120 km长的光纤上传输无误码的效果和较清晰的眼图。     

氮和铋离子注入InP损伤机理的分析

氮和铋注入InP的晶格损伤问题在本文中进行了分析。特别是研究了不同剂量的两种离子注人到InP中所引起的晶格结构的崩溃过程,以及这两种离子引起晶格损伤过程的差异。对于低温和常温的注入过程的分析给出了空位扩散的激活能。从实验和理论分析给出了空位的扩散率为1.94×10~(-4)cm~2/S。该值表明铋注入InP的过程是热峰效应的过程(即入射离子在注入碰撞区域内形成了局部的高温区)。背散射技术是晶格损伤分忻的主要手段。对于氦分析InP时引入的附加损伤也做了修正,背散射和离子注入都是在共国的萨尔福特大学(University of Salford)完成的。     

（001）应变对正交相Ca2P0.25Si0.75能带结构及光学性质的影响

为了研究(001)应变对正交相Ca2P0.25Si0.75能带结构及光学性质的影响,采用第一性原理贋势平面波方法对(001)应变下正交相Ca2P0.25Si0.75的能带结构及光学性质进行了模拟计算.计算结果表明:晶格(001)面发生100%~116%张应变时,带隙随着应变增加而减小;在晶格发生88%~100%压应变时,带隙随着张应变的增加而增加;84%~88%压应变时,带隙随着压应变的增加而减小.当施加应变后光学性质发生显著的变化:随着压应变的增加,静态介电常数、折射率逐渐减小,张应变则增大.施加压应变反射向高能方向偏移,施加张应变反射向低能方向偏移,但施加应变对反射区域的影响不显著.施压应变吸收谱、光电导率的变化与介电函数和折射率相反.综上所述,(001)应变改变了Ca2P0.25Si0.75的电子结构和光学常数,是调节Ca2P0.25Si0.75光电传输性能的有效手段.     

Mg:Sc:Fe:LiNbO_3晶体缺陷结构和全息存储性能

采用提拉法,从Li/Nb变化(0.94,1.05,1.20,1.38)的熔体中生长出Mg:Sc:Fe:LiNbO_3晶体。Li/Nb=1.05的晶体OH~-振动吸收峰在3504cm~(-1)处出现的主吸收峰,且在3466cm~(-1)、3481m~(-1)处有两附加峰。Li/Nb=1.38的晶体OH~-振动吸收峰在3535 cm~(-1)处出现附加吸收峰。红外光谱结果表示Li/Nb=1.05的晶体是近化学剂量比的,且Sc掺质优先于Mg掺质达到阈值浓度。采用透射光斑畸变法测得Mg:Sc:Fe:LiNbO_3晶体(Li/Nb=1.05)的抗光损伤能力为2.0×10~4W/cm~2,比Fe:LiNbO_3提高了三个数量级。采用波长为632.8nm的He—Ne激光器作为光源,通过二波耦合方法测试晶体全息存储性能。实验结果表明:随着Li/Nb的增加,晶体的写入时间缩短,晶体的衍射效率降低,光折变灵敏度增加,动态范围减少。在一系列晶体中,Mg:Sc:Fe:LiNbO_3晶体(Li/Nb=1.05)更加适合作为全息存储介质。     

A Fictitious Time Integration Method for Multi-Dimensional Backward Heat Conduction Problems

In this article, we propose a new numerical approach for solving these multi-dimensional nonlinear and nonhomogeneous backward heat conduction problems (BHCPs). A fictitious time t is employed to transform the dependent variable u(x, y, z, t) into a new one by (1+t)u(x, y, z, t)=: v(x, y, z, t, t), such that the original nonlinear and nonhomogeneous heat conduction equation is written as a new parabolic type partial differential equation in the space of (x, y, z, t, t). In addition, a fictitious viscous damping coefficient can be used to strengthen the stability of numerical integration of the discretized equations by utilizing a group preserving scheme. Six numerical experiments illustrate that the present algorism can be employed to recover the initial data very well. Even under the very large noisy final data, the fictitious time integration method is also robust against noise.     

Mathematical modeling of a transient heat-conduction process

A numerical algorithm is proposed for solution of the transient heat-conduction equation by the Monte Carlo method. The calculated values of the temperature are compared with experimental data.Notation U temperature - t time - a thermal diffusivity - x, y, z coordinates - (x, y, z, t) temperature on the surface of the body - g(x, y, z) initial temperature - T finite time of investigation of the process - (x, y, z, t) = F (x, y, z, t)/c where F(x, y, z, t) is an internal heat source - c specific heat - density Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 39, No. 4, pp. 745–747, October, 1980.     

A Fictitious Time Integration Method for Multi-Dimensional Backward Wave Problems

We address a new numerical approach to deal with these multi-dimensional backward wave problems (BWPs) in this study. A fictitious time τ is utilized to transform the dependent variable u(x, y, z, t) into a new one by (1+τ)u(x, y, z, t)=: v(x, y, z, t, τ), such that the original wave equation is written as a new hyperbolic type partial differential equation in the space of (x, y, z, t, τ). Besides, a fictitious viscous damping coefficient can be employed to strengthen the stability of numerical integration of the discretized equations by using a group preserving scheme. Several numerical instances demonstrate that the present scheme can be utilized to retrieve the initial wave very well. Even though the noisy final data are very large, the fictitious time integration method is also robust against disturbance.     

A New Quasi-Boundary Scheme for Three-Dimensional Backward Heat Conduction Problems

In this study, we employ a semi-analytical scheme to resolve the three-dimensional backward heat conduction problem (BHCP) by utilizing a quasi-bound -ary concept. First, the Fourier series expansion method is used to estimate the temperature field u(x, y, z, t) at any time t < T. Second, we ponder a direct regularization by adding an extra term a(x, y, z, 0) to transform a second-kind Fredholm integral equation for u(x, y, z, 0). The termwise separable property of the kernel function allows us to acquire a closed-form regularized solution. In addition, a tactic to determine the regularization parameter is recommended. We find that the proposed method is robust and applicable to the three-dimensional BHCP when several numerical experiments are examined.     

非化学计量比对(K0.465Na0.465Li0.07)(Nb0.95Sb0.05)O3无铅压电陶瓷结构及性能的影响

通过传统固相合成工艺制备了(K0.465+xNa0.465+yLi0.07)(Nb0.95-zSb0.05)O3(x,y,z=-0.01～0.02)无铅压电陶瓷,研究了非化学计量比对陶瓷结构及压电性能的影响。结果表明符合化学计量比的陶瓷具有四方钙钛矿结构;在实验范围内,K和Nb的过量或少量均不会改变体系的相结构,而Na过量将会导致体系正交-四方相变温度升高到室温以上,并且正交-四方相变温度随y的增加而升高;过量添加约0.5%(摩尔分数)的K或Na便能补偿在高温烧结时的碱金属元素的挥发损失,进而提高陶瓷的压电性能;该体系陶瓷的组分在较大范围内变化时(如当y=z=0时,x=0～0.02;当x=z=0时,y=0～0.01;以及当x=y=0时,z=-0.01～0.005),仍然能保持d33>200pC/N和kP>40%这样较好的性能。上述结果不仅有利于在研究中材料制备工艺的重复,而且有利于当材料在器件应用时所面临的规模化生产。     

三维C/C复合材料的压缩性能及破坏机制

采用扫描电镜、激光共聚焦显微镜观察和力学性能测定的方法,研究了三维C/C复合材料微观结构形貌,以及材料x向、y向和z 向的压缩性能。结果表明,材料内部缺陷明显,纤维束/基体界面结合较弱,材料z向压缩强度和破坏应变均大于x向和y向,压缩应力-应变曲线开始阶段近似线性,随着载荷的增加,曲线表现出明显的非线性特征。从宏观上考察了材料的压缩破坏机制,材料x向、y向和z向破坏模式均为剪切型破坏,纤维/基体界面结合强度对破坏模式影响明显。     

Optical and electrical H/sub 2/- and NO/sub 2/-sensing properties of Au/In/sub x/O/sub y/N/sub z/ films

In this paper, we describe the optical and electrical gas-sensing properties of In/sub x/O/sub y/N/sub z/ films with an ultrathin gold promoter overlayer. We have fabricated In/sub x/O/sub y/N/sub z/ films with a nanocrystalline porous structure by RF-sputtering in Ar/N/sub 2/ followed by an annealing process. Gold particles with 20-30-nm diameter have been formed on top of the In/sub x/O/sub y/N/sub z/ films by dc sputtering and an annealing process. We have investigated the optical H/sub 2/and NO/sub 2/-sensing properties (change of absorbance) and also the electrical sensing effect (change of electrical resistance) for these two gases. A combined optical/electrical sensor for H/sub 2//NO/sub 2/ is proposed.     

固体氧化物燃料电池复合掺杂材料研究进展

概述了中温固体氧化物燃料电池要件使用的新型复合掺杂材料研究及制备进展,采用差示扫描量热法（DSC）,热重法（TG）与变温度X射线衍射对La1-xSrxMn1-yCoyO3,La1-x-zSrxCaZmN1-YCoyO3复合掺杂钙钛矿结构氧化的固相烧结合成过程进行了研究,提出了一些将来应重点研究的问题。     

Imaging and transforming transmission through a medium with nonrotation-symmetric gradient index

The objective of this paper is to show that it is possible to transmit a paraxial optical image and transform through a dielectric inhomogeneous medium whose refractive index is given by n2 = n2(1)(z) + n2(0)[hz(z)x + h2(z)y - g2(z)(x2 + y2)], where n0 = n1(0), and n1, g, h1 and h2 are arbitrary functions of z. The optical image transmission, with a scaling factor F = H2(zm), m being an integer, is obtained at planes z = zm such that H1(zm) = 0 (the image condition), and the optical transform transmission is obtained at planes z = zm such that H2(zm) = 0 (the transform condition), where Hz(z) and H2(z) are two independent solutions of the paraxial ray equation H(z) + g2(z)H(z) = 0 with the initial conditions H1(0) = 0,H1(0) = 1,H2(0) = 1, and H2(0) = 0, where the point denotes the derivative with respect to z. Finally, we show that this medium can be represented by a transmittance function similar to the spherical-lens transmittance function and thus can be an element of image-forming systems.