K0.9Li0.1（Ta0.5Nb0.5）O3晶体压电应变系数的测量

用准静态ｄ＿（３３）测量仪和干涉法相结合。测量了Ｋ＿（０．９）Ｌｉ＿（０．１）（Ｔａ＿（０．５）Ｎｂ＿（０．５）Ｎｂ＿（０．５））Ｏ＿３晶体的压电应变系数。结果为：ｄ＿（３３）＝８６．０，ｄ＿（３３）＝一２９．５，ｄ＿（１５）＝１１２．９×１０￣（－１２）Ｃ／Ｎ．     

InAs／InP_（0．7）Sb_（0．3）热电子晶体管的f_T及f_（max）

用电荷控制及热电子弹道运动模型计算ＩｎＡｓ／ＩｎＰ０．７Ｓｂ０．３热电子晶体管的截止频率ｆＴ及最高振荡频率ｆｍａｘ。结果表明，ｆＴ、ｆｍａｘ分别达到２８０ＧＨｚ及６００ＧＨｚ。并指出，通过生长ＧａＳｂ中间层，ＩｎＡｓ／ＩｎＰ０．７Ｓｂ０．３ＨＥＴ可在ＧａＡｓ衬底上实现单片集成。     

Pb（WO4）0.9（MoO4）0.1晶体的生长及闪烁性能研究

以０．１ｍｏｌＭｏＯ３取代ＰｂＷＯ４中ＷＯ３生长Ｐｂ（ＷＯ４）０．９（ＭｏＯ４）０．１晶体。测试了晶体的密度、透射率和闪烁性能。克服了ＰｂＷＯ４晶体在生长中出现的开裂。生长出质量优良的Ｐｂ（ＷＯ４）０．９（ＭｏＯ４）０．１晶体。     

Zn_（0．65）Cd_（0．35）Se－ZnSe量子阱自电光效应器件的制备和

利用ＭＯＣＶＤ技术和光电子器件工艺成功地制备了Ｐ－ｉ－ｎ结构的Ｐ－ＺｎＳｅ－（Ｚｎ０．６５Ｃｄ０．３５Ｓｅ－ＺｎＳｅＭＱＷ）－ｎ－ＺｎＳｅ自电光效应器件（ＳＥＥＤ）。在这种自由光效应器件中，在反向偏置电压下实现了由量子限制斯塔克效应（ＱｕａｎｔｕｍＣｏｎｆｉｎｅｄＳｔａｒｋＥｆｆｅｃｔ）引起的电光调制。     

Ba（Ti0．91Zr0．09）0．99Al0．01O3陶瓷的介电弛豫特性

采用固相反应法制备了Ba1-xBi（Ti0.09Zr0.09）0.99Al0.01O3陶瓷,借助XRD、Agilent4284A、ZT-I电滞回线测量仪,研究了Bi^3＋和Al^3＋共掺杂后对陶瓷的相结构和介电特性的影响。研究结果表明,掺杂后Ba（Ti0．91Zr0．09）0．99Al0．01O3陶瓷的体积密度在x=0．03时,可达5．859g／cm^3,XRD结果显示,在x≤0．01时,衍射峰具有单一的四方BaTiO3结构,观察介电温谱（-30℃≤T≤130℃,10^-1kHz≤f≤10^3kHz,其中f为频率）可发现陶瓷从正常铁电体转变成弛豫铁电体,电滞回线显示矫顽场（Ec）和剩余极化强度（Pt）小,即Ec=0．93kV／cm,Pc=2．63μC／cm^2。     

有序Ga_（0．5）In_（0．5）P光致发光的研究

本文用光致发光（ＰＬ）研究了ＭＯＣＶＤ生长的有序Ｇａ０．５Ｉｎ０．５Ｐ外延层的光学性质．发现有序程度较强的Ｇａ０．５Ｉｎ０．５Ｐ样品的ＰＬ谱中，能量最高的峰的强度随温度升高，先减弱，然后增强，最后又减弱．我们提出了一个有序Ｇａ０．５Ｉｎ０．５Ｐ的模型，认为有序Ｇａ０．５Ｉｎ０．５Ｐ外延层是阱定随机分布的Ⅱ型多量子阱结构，能带边之下存在带尾态。并用该模型对实验结果进行了较好的解释．     

高电场下In_（0．53）Ga_（0．47）As／In_（0．52）Al_（0．

研究在外加电场０～５０ｋＶ／ｃｍ范围内，Ｉｎ０．５３Ｇａ０．４７Ａｓ／Ｉｎ０．５２Ａｌ０．４８ＡＳ宽量子阱电透射光谱中１１ｈ激子跃迁的谱线宽度（ＦＷＨＭ）．它可分解为由温度及界面粗糙度引起的非均匀展宽（高斯型）和由外场引起的均匀展宽（劳伦兹型）．用线性叠加的近似公式代替高斯和劳伦兹方程的卷积，再与实验光谱拟合．谱线总宽度、高斯展宽成份及线性叠加系数η均作为拟合参数得到，从而可得劳伦兹展宽．将与外场的关系曲线与理论作比较，在数量级上一致．     

MOCVD和GSMBE生长Ga_（0．5）In_（0．5）P外延层中有序结构的研究

用ＭＯＣＶＤ在（１００）、ＧＳＭＢＥ在（１００）和（１１１）ＢＧａＡｓ上生长了ＧａＩｎＰ外延层．ＰＬ测试表明，（１００）衬底上ＧａＩｎＰＰＬ峰的能量比计算的带隙分别小４３（ＧＳＭＢＥ生长）和１０４ｍｅＶ（ＭＯＣＶＤ生长）．用Ｋｕｒｔｚ等人的模型对ＭＯＣＶＤ和ＧＳＭＢＥ生长的ＧａＩｎＰ中有序度的不同进行了解释．并讨论了衬底晶向对ＧａＩｎＰ中有序程度的影响．     

（100）和（111）BGaAs衬底上的In_（0．14）Ga_（0．86）As／GaAs量子阱的发光特性和光跃迁能量计算

在（１００）和（１１１）ＢＧａＡｓ衬底上，同时用ＭＯＣＶＤ生长出Ｉｎ０．１４Ｇａ０．８６Ａｓ多量子阱结构．对两种晶向的样品进行了低温（２Ｋ）光致发光谱特性对比研究，测量与理论计算的光发射能量对比表明：（１００）面样品两者一致，而（１１１）Ｂ样品计算值比测量值高出１０～１５ｍｅＶ．这一差别用（１１１）Ｂ面量子阱中的压电效应产生的自建电场引起的发射能量红移作出解释．     

功率双基区晶体管（DUBAT）及其压（流）控调频效应

在重点考虑了提高击穿电压和增大电流容量的基础上，设计并研制出功率型ＤＵＢＡＴ。其主要参数达到：ＢＶ（ＣＥ０）≥１２０Ｖ，Ｉ（ＣＭ）≥２Ａ，ＲＮ≈５０～１１０Ω，Ｐ（ＣＭ）≥１０Ｗ。并在此器件上首次发现了电压（流）控制调节脉冲频率效应。     

Research on application of variable coding modulation system based on Digital Video Broadcasting ‐ Satellite ‐ 2nd Generation in data transmission of near‐earth remote sensing satellite

In order to make full use of the link resources for data transmission from near‐earth remote sensing satellites, variable coding modulation (VCM) system is used to fully utilize the system link margin to improve the satellite data transmission performance. By analyzing the dynamic link under the VCM data transmission system, the contribution of the VCM system to the satellite data link optimization is studied from the perspective of engineering application, which can provide reference for the data link design of remote sensing satellites. Applying the flow design, for the currently adopted transmission system of X band, compared with traditional constant coding modulation (CCM) system, the average link performance of VCM system can be increased by 42.1% in single‐station transmission mode and 53.3% in dual‐station relay mode through the exampled analysis.     

LB法制备的P(VDF-TrFE)共聚物薄膜其光学和电学特性研究

运用郎缪尔-布尔吉特法在聚酰亚胺衬底上制备聚偏氟乙烯及三氟乙烯(P(VDF-TrFE))共聚物薄膜.不同厚度薄膜的X射线衍射结果表明,薄膜具有良好的结晶特性,取向为(110).运用波长范围为300～1300nm的椭圆偏振光谱仪对薄膜光学特性进行了表征;运用Cauchy模型对不同角度(θ=75°和85°)测得的Ψ和Δ数据进行了拟合.获得了P(VDF-TrFE)薄膜的光学参数n, k, α以及薄膜的厚度.另外对薄膜的铁电性质的测量,其剩余极化达到了6.3μC/cm2, 矫顽电场为100MV/cm.介电测量得到了薄膜两个明显的相变,铁电-介电相变以及β弛豫.     

Bi_(3.15)Nd_(0.85)Ti_3O_(12)纳米结构的制备与XPS研究

采用水热法在低温合成了铋层状钙钛矿结构Bi_(3.15)Nd_(0.85)Ti_3O_(12)(BNdT)纳米材料,利用X-射线衍射(XRD)、扫描电子显微镜(SEM)表征产物的晶相和形貌,研究了反应温度和聚乙烯醇(PVA)对水热合成BNdT纳米结构的影响,运用X-射线光电子能谱(XPS)对BNdT纳米结构的化学组分和元素价态进行了表征.结果表明,反应温度和PVA对水热合成BNdT纳米结构的形貌有较大影响;XPS研究显示BNdT纳米结构的表面存在氧空位和轻微的Bi过量.     

微波烧结Ba_(6-3x)Sm_(8+2x)Ti_(18)O_(54)陶瓷材料的初步研究

研究了Ba_(6-3x)Sm_(8+2x)Ti_(18)O_(54)(x=0.67,BST)陶瓷材料的微波烧结情况,从烧结特性、微结构与相组成及微波介电性能等方面对微波烧结的样品与传统工艺制得的样品进行了对比.结果表明, 与传统制备工艺相比,微波烧结BST陶瓷缩短了烧结周期,并促进了样品的致密化,其物相组成和传统烧结的样品没有区别,且晶粒细小分布均匀.微波烧结BST陶瓷可获得较优的微波介电性能:介电常数ε_r=82.89,品质因数与频率之积Qf=8 450 GHz(频率f=4.75 GHz),谐振频率温度系数τ_f=22.58×10~(-6)/℃.     

Ba6-3xNd8+2xTi18O54陶瓷的微波合成及低温烧结

采用微波加热法于1 100℃保温30 min(升温速率为20℃/min)合成Ba6-3xNd8+2xTi18O54(x=0.30～0.75,BNT)陶瓷粉末,再添加质量分数45％的B2O3-SiO2-CaO-MgO( BM)玻璃,在马弗炉中于900℃烧结2h制得BNT陶瓷.研究了所制陶瓷的微观结构及性能.结果表明:微波...     

Nonlinear Tracking Control for a Hard Disk Drive Dual-Stage Actuator System

This paper presents a nonlinear tracking control method for a hard disk drive dual-stage actuator (DSA) system that consists of a voice coil motor (VCM) actuator and a piezoelectric (PZT) microactuator. Conventional track seeking controllers for DSA systems were generally designed to enable the VCM actuator to approach the target track without overshoot. However, we observe that this strategy is unable to achieve the minimal settling time when the target tracks are beyond the PZT actuator stroke limit. To further reduce the settling time, we design the VCM actuator controller to yield a closed-loop system with a small damping ratio for a fast rise time and certain allowable overshoot. Then, a composite nonlinear control law is designed for the PZT actuator to reduce the overshoot caused by the VCM actuator as the system output approaches the target track. Experimental results show that the proposed dual-stage servo outperforms the conventional dual-stage servo in short-span seeking and, additionally, achieves better track following accuracy than the VCM only single-stage servo.     

Settling control and performance of a dual-actuator system for hard disk drives

This paper presents a settling control of a dual-actuator system for hard disk drives. The dual-actuator system consists of a voice coil motor (VCM) as a first stage actuator and a push-pull-type piezo-electric transducer (PZT) as a second-stage actuator. The settling controller is designed in three steps. In the first step, the VCM controller is designed so that the VCM feedback loop has basic performance and appropriate stability. In the second step, the PZT controller and a decoupling filter are designed in order to achieve superior performance of the dual-actuator system. The decoupling filter, which is placed between the PZT controller output and the VCM controller input, is a PZT output estimator so that the PZT actuator output is canceled at the VCM controller input. In the third step, the reference trajectory is designed for fast and smooth settling. In this study, the closed-loop sensitivity function is used as a performance index, and the gain and phase margins of the open-loop characteristic are used as stability measures. Experimental results show that the dual actuator system with the proposed settling controller achieves better performance than a single actuator system with the same VCM and a conventional settling controller.     

Sol-Gel法制备Bi_(3.15)Nd_(0.85)Ti_3O_(12)铁电薄膜

采用溶胶-凝胶(Sol-Gel)法在Pt/Ti/SiO_2/Si衬底上制备Bi_(3.15)Nd_(0.85)Ti_3O_(12)薄膜,发现制备的薄膜具有单一的钙钛矿晶格结构,且表面平整致密.对Bi_(3.15)Nd_(0.85)Ti_3O_(12)薄膜的电学性能进行了研究.结果表明,室温下,在测试频率1 MHz时,其介电常数为213,介电损耗为0.085;在测试电压为350 kV/cm,其剩余极化值、矫顽场强分别为39.1 μC/cm~2、160.5 kV/cm;表现出良好的抗疲劳特性和绝缘性能.     

GaAs衬底上（ZnS）n／（ZnSe）n（001）超晶格的光学性质

本文用Ｌｉｎｅａｒｉｚｅｄ－Ｍｕｆｆｉｎ－Ｔｉｎ Ｏｒｂｉｔａｌｓ能带方法，计算ＧａＡｓ衬底上（ＺｎＳ）ｎ／（ＺｎＳｅ）ｎ（００１）超晶格的能带结构。计算中采用外加调整势进行带隙修正，从而得到较准确的能带结构和波函数。在此基础上计算了超晶格系统的光学介电函数虚部ε２（ω）。结果表明，该超晶格系统的光学性质结合了ＺｎＳ和ＺｎＳｅ体材料光学性质的特点，在相当宽的能量范围内有较好的光谱响应，并且该超晶格     

Thin ferroelectric poly(vinylidene fluoride-chlorotrifluoro ethylene) films for thermal history independent non-volatile polymer memory

In this study, we investigated the molecular and microstructures of thin poly(vinylidene fluoride-chlorotrifluoro ethylene) (PVDF-CTFE) copolymer films with three different CTFE compositions of 10, 15, 20 wt% with respect to PVDF in relation with their ferroelectric properties. All PVDF-CTFE annealed at 130 °C showed consecutive TTTT trans conformation with β type crystals while films molten and re-crystallized from a temperature above their melting points exhibited α type crystals with characteristic TGTG conformation. Microstructures of the films treated with the two different thermal histories also supported the formation of β and α type crystals with hundreds of nanometer scale sphere caps and micron level spherulites, respectively. Interestingly, PVDF-CTFE films with both α and β type crystals gave rise to relatively high remnant polarization of approximately 4 μC/cm² in metal/ferroelectric/metal capacitors regardless of the composition of CTFE. The ferroelectric polarization of a PVDF-CTFE film independent of thermal processing history allowed a wide processing window and easy fabrication protocol, resulting in a non-volatile ferroelectric field effect transistor memory which exhibited saturated hysteresis loops with the current ON/OFF ratio of approximately 10³ at ±60 V sweep and reliable data retention.