CNT改性水泥基压电复合材料制备与压电性能

采用Fenton试剂结合超声分散和紫外线照射对CNT进行表面修饰,采用溶胶-凝胶法制备纳米级压电陶瓷(PZT),以CNT作为增强相,结合手动压片与直流极化工艺,制备出CNT改性水泥基压电复合材料。通过红外光谱和分光光度测试,当超声温度60℃、紫外线照射1h时,CNT分散液分散均匀,分散性最好。通过显微测试,CNT和PZT在水泥基压电复合材料中分散均匀,但结构致密度下降。压电常数和相对介电常数分别达到50.6pC/N、412.0,与相同条件下制备的PZT水泥基压电材料相比,分别提高18.5%、4.1%。同时,分散的CNT能发挥宏观量子隧穿效应,使复合材料在几乎不降低材料介电性能情况下更易极化。     

PZT压电陶瓷的总剂量辐照效应实验研究

采用传统固相反应法制备PZT压电陶瓷材料,并制作成平行平板无源电容器结构。在ELV-8电子直线加速器上对其进行总剂量辐照效应实验,对辐照前后PZT材料的介电和压电性能参数进行了测试和比较。实验结果表明,PZT材料平行平板电容器的压电性能抗总剂量水平可达2×108rad(Si),领先国际水平。     

低温烧结PZT压电陶瓷材料

本文介绍了低温烧结PZT压电陶瓷材料的发展概况,给出了不同方法制备的低温烧结PZT压电陶瓷材料的性能,并对降低PZT陶瓷烧结温度的各种方法进行了评价。     

基于PZT压电薄膜的压力传感器工艺研究

选用敏感材料锆钛酸铅(PZT),优化微机电系统(MEMS)微加工工艺,制作了硅基PZT压电薄膜叉指式电极结构的MEMS压力传感器。在基体Au/Ti/LNO/SiO_2/Si<100>上,采用溶胶-凝胶(Sol-Gel)法,在650℃高温下采用分层退火的方式进行退火,得到厚1.2μm的PZT压电薄膜。薄膜表面均匀,无裂纹。利用光刻工艺和低压溅射工艺得到平行叉指电极。制作完成PZT压电薄膜结构的微压力传感器,在弹性薄膜上施加压力,其电压输出性能较好,说明基于压电薄膜的叉指电极结构可行,为基于纳米纤维结构的微压力传感器的制作奠定了理论基础。     

基于压电效应的MEMS振动式微能源器件

设计了一种硅基压电功能材料的四悬臂梁-中心质量块结构MEMS振动式微能源器件,可将环境振动能量有效转化为电能。采用溶胶-凝胶法制备硅基锆钛酸铅(PbZr0.53Ti0.47O3,PZT)压电功能薄膜,经干/湿法刻蚀和溅射沉积等MEMS工艺实现器件功能结构的制备。研制的器件整体结构尺寸为7 000μm×7 000μm×300μm,单个PZT压电单元面积为0.149 6 mm2。将悬臂梁上4个压电单元串联以实现输出最大化,测试结果表明,器件的谐振频率为300 Hz,适于低频振动环境;输出电压在一定范围内随加速度增加而增大;在加速度为10 g时压电单元单位面积输出电压达1.19 mV/mm2。     

溶胶-凝胶法制备PZT薄膜研究进展

随着微机电系统(MEMS)产业的快速发展,铁电薄膜材料作为微机电器件的重要组成部分而愈受重视。锆钛酸铅(PZT)薄膜具有优越的压电性、热释电性及光电性等性能,在微电子、压电、光学及半导体等领域展现了巨大的应用潜力。因此,高性能PZT薄膜的制备技术及制备工艺一直备受关注。其中,溶胶凝胶法因具有易于控制成分,所需设备成本低及制备薄膜的均匀性好等优点而被广泛用于PZT薄膜制作中。该文在溶胶凝胶法基本原理及制作工艺的基础上,着重分析了溶胶凝胶法制备PZT薄膜的研究现状,总结了当前溶胶凝胶法的技术特点,并指出了研究中存在的不足及未来的潜在改进方向。     

纳米PZT粉体制备及PZT/水泥基复合材料压电性能

采用溶胶-凝胶法,结合正交试验设计,研究了不同反应条件((CH3COO)2Pb浓度、pH值、反应时间和煅烧温度)对PZT粉体结晶程度和晶粒大小的影响。用压制成型法制备出PZT压电陶瓷和PZT/硫铝酸盐水泥基复合材料。用正交极差与方差法分析了反应条件对PZT粉体物相与粒度及陶瓷片和复合材料的压电与介电性能的影响,得出粉体最佳制备工艺。结果显示:最佳反应条件为(CH3COO)2Pb浓度为15%,pH=5.0,反应时间2h,煅烧温度600℃;煅烧温度对陶瓷片及复合材料的压电与介电性能影响最显著;相应陶瓷片压电常数d33、相对介电常数εr分别为38.5pC/N、1.3;而复合材料的d33、εr分别为4.4pC/N、29.4,数值偏低可能是水泥水化不充分,结构不致密所致。     

溶胶-凝胶工艺对纳米级富锆PZT粉末制备的影响

采用溶胶-凝胶工艺制备了纳米级富锆PZT粉末,分析比较了不同溶胶-凝胶过程对制备工艺和合成粉末性能的影响.研究表明合适的反应前驱物、溶液pH值、胶凝剂和热处理条件,对于提高制备粉体结晶度和活性,简化制备工艺、降低反应成本是极其重要的;以硝酸铅为铅源合成粉末具有较好的活性.     

铅锰锑系压电陶瓷介电性研究

采用预合成及掺杂适量MnO2等工艺制备了钙钛矿结构为主的压电陶瓷材料Pb（Mn1/3Sb2/3)x(Zn1/3Nb2/3)y(Zr0.535Ti0.465)1-x-yO3,此材料具有机电耦合系数高、介质损耗小、介电常数与机械品质因数适中的特点。引入MnO3使其成为单一的钙态矿结构,并且提高了材料的介电与压电性能。     

PT种子层对PZT薄膜结晶及压电性能的影响

采用溶胶-凝胶法(Sol-Gel)在Pt/Si衬底上制备了PbTiO3 (PT)薄膜和Pb (Zrx,Ti1-x)O3(PZT)薄膜,研究了退火温度以及PT种子层对PZT薄膜结晶及压电性能的影响。X射线衍射(XRD)结果表明,制备的PZT薄膜为纯钙钛矿结构的多晶薄膜,有PT种子层的PZT薄膜晶粒尺寸更大,(110)面取向度更高,结晶性能更好;原子力显微镜(AFM)结果表明,制备的薄膜表面形貌比较平整、均匀、无裂纹;压电力显微镜(PFM)结果表明,压电力显微镜(PFM)结果表明,有PT种子层时,PZT薄膜的平均压电系数d33为128～237 pm/V,无PT种子层时平均压电系数d33为21～29 pm/V。在升温速率为10 ℃/s的退火条件下保温10 min时,随着退火温度的升高,PZT薄膜晶粒尺寸增大,粗糙度增大,(110)面取向度升高,平均压电系数d33增大。PT种子层能够有效的改善PZT薄膜的结晶性能和压电性能。     

Curved crystal spectrometer for the measurement of X-ray lines from laser-produced plasmas

In order to diagnose the laser-produced plasmas, a focusing curved crystal spectrometer has been developed for measuring the X-ray lines radiated from a laser-produced plasmas. The design is based on the fact that the ray emitted from a source located at one focus of an ellipse will converge on the other focus by the reflection of the elliptical surface. The focal length and the eccentricity of the ellipse are 1350 mm and 0.9586, respectively. The spectrometer can be used to measure the X- ray lines in the wavelength range of 0.2-0.37 nm, and a LiF crystal （200） （2d = 0.4027 nm） is used as dispersive element covering Bragg angle from 30° to 67.5°. The spectrometer was tested on Shengnang- Ⅱ which can deliver laser energy of 60-80 J/pulse and the laser wavelength is 0.35 μm. Photographs of spectra including the 1 s2p ^1P1-1s^2 ^1S0 resonance line（w）, the 1s2p ^3P2-1s^2 1S0 magnetic quadrupole line（x）, the 1s2p ^3P1-1 s^2 ^1S0 intercombination lines（y）, the 1 s2p ^3S~1-1 s^2 ^1S0 forbidden line（z） in helium-like Ti Ⅹ Ⅺ and the 1 s2s2p ^2P3/2-1 s622s ^2S1/2 line（q） in lithium-like Ti Ⅹ Ⅹhave been recorded with a X-ray CCD camera. The experimental result shows that the wavelength resolution（λ/△ 2） is above 1000 and the elliptical crystal spectrometer is suitable for X-ray spectroscopy.     

Preparation and Characterization of TaN ALD Precursors

High purity organic-tantalum precursors for thin film ALD TaN were synthesized and characterized.Vapor pressure and thermal stability of these precursors were studied.From the vapor pressure analysis,it was found that TBTEMT has a higher vapor pressure than any other published liquid TaN precursor,including TBTDET,TAITMATA,and IPTDET.Thermal stability of the alkyl groups on the precursors was investigated using a 1H NMR technique.The results indicated that the tertbutylimino group is the most stable group on TBTDET and TBTEMT as compared to the dialkylamido groups.Thermal stability of TaN precursors decreased in the following order:TBTDET ＞ PDMAT ＞ TBTEMT.In conclusion,precursor vapor pressure and thermal stability were tuned by making slight variations in the ligand sphere around the metal center.     

Electronic Structure of Semiconductor Nanocrystals

This paper reviews our recent development of the use of the large-scale pseudopotential method to calculate the electronic structure of semiconductor nanocrystals, such as quantum dots and wires, which often contain tens of thousands of atoms. The calculated size-dependent exciton energies and absorption spectra of quantum dots and wires are in good agreement with experiments. We show that the electronic structure of a nanocrystal can be tuned not only by its size,but also by its shape. Finally,we show that defect properties in quantum dots can be significantly different from those in bulk semiconductors.     

Critical Stage Rule-Based Real Time Dispatch（RTD）System in Highly-Mixed-Products （HMP） FAB

An improving utilization and efficiency of critical equipments in semiconductor wafer fabrication facilities are concerned. Semiconductor manufacturing FAB is one of the most complicated and cost sensitive environments. A good dispatching tool will make big difference in equipment utilization and FAB output as a whole. The equipment in this paper is In-Line DUV Scanner. There are many factors impacting utilization and output on this equipment group. In HMP environment one of the issues is changing of reticule in this area and idle counts due to load unbalance between equipments. Here we'll introduce a rule-based RTD system which aiming at decreasing the number of recipe change and idle counts among a group of scanner equipment in a high-mixed-products FAB.     

GaAsSb/InAlAs PA DHBTs Grown by Production MBE

The epi material growth of GaAsSb based DHBTs with InAlAs emitters are investigated using a 4 × 100mm multi-wafer production Riber 49 MBE reactor fully equipped with real-time in-situ sensors including an absorption band edge spectroscope and an optical-based flux monitor. The state-of-the-art hole mobilities are obtained from 100nm thick carbon-doped GaAsSb. A Sb composition variation of less than ± 0.1 atomic percent across a 4 × 100mm platen configuration has been achieved. The large area InAlAs/GaAsSb/InP DHBT device demonstrates excellent DC characteristics,such as BVCEO＞6V and a DC current gain of 45 at 1kA/cm2 for an emitter size of 50μm × 50μm. The devices have a 40nm thick GaAsSb base with p-doping of 4. 5 × 1019cm-3 . Devices with an emitter size of 4μm × 30μm have a current gain variation less than 2% across the fully processed 100mm wafer. ft and fmax are over 50GHz,with a power efficiency of 50% ,which are comparable to standard power GaAs HBT results. These results demonstrate the potential application of GaAsSb/InP DHBT for power amplifiers and the feasibility of multi-wafer MBE for mass production of GaAsSb-based HBTs.     

Influence of polarization extinction ratio on distributed polarization coupling detection

Distributed polarization coupling in polarization-maintaining fibers can be detected by using a white light Michelson interferometer. This technique usually requires that only one polarization mode is excited. However, in practical measurement, the injection polarization direction could not be exactly aligned to one of the principal axes of the PMF, so the influence of the polarization extinction ratio should be considered. Based on the polarization coupling theory, the influence of the incident polarization extinction on the measurement result is evaluated and analyzed, and a method for distributed polarization coupling detection is developed when both two orthogonal eigenmodes are excited.     

Noise character analysis and the restraint of self-pulsation laser diodes

We calculate the Langevin noise sources of self-pulsation laser diodes, analyze the effects of active region noise and saturable-absorption region noise on the power fluctuation as well as period fluctuation, and propose a novel method to restrain the noise effects. A visible SIMULINK model is established to simulate the system, The results indicate that the effects of noise in absorption region can be ignored; that with the increase of DC injecting current, the noise effects enhance power jitter, and nevertheless, the period jitter is decreased; and that with external sinusoidal current modulating the self-pulsation laser diode, the noise-induced power jitter and period jitter can be suppressed greatly. This work is valuable for clock recovery in all-optical network.     

High-quality single-crystal CdSe nanoribbons and their optical properties

Large-scale synthesis of single-crystal CdSe nanoribbons is achieved by a modified thermal evaporation method, in which two-step-thermal-evaporation is used to control CdSe sources＇ evaporation. The synthesized CdSe nanoribbons are usually several micrometers in width, 50 nm in thickness, and tens to several hundred micrometers in length. Studies have shown that high-quality CdSe nanoribbons with regular shapes can be obtained by this method. Room-temperature photolumines-cence indicates that the lasing emission at 710 nm has been observed under optical pumping （266 nm） at power densities of 25-153 kW/cm^2. The full width half maximum （FWHM） of the lasing mode is 0.67 nm     

Propagation of hermite-cosh-gaussian beams passing through ABCD optical system with an annular aperture

By using the expansion of the aperture function into a finte sum of complex Gaussian functions, the corresponding analytical expressions of Hermite-cosh-Gaussian beams passing through annular apertured paraxially and symmetrically optical systems written in terms of ABCD matrix were derived, and they could reduce to the cases with squared aperture. In a similar way, the corresponding analytical expressions of cosh-Gaussian beams through annular apertured ABCD matrix were also given. The method could save more calculation time than that by using the diffraction integral formula directly.     

中国建立EB级存储实验室,致力云计算应用(英文)

正With the support of 863 programs,Sugon Information Industry Co.,Ltd.,set up a dawning EB-class storage laboratory to address massive data storage requirements and largescale cloud computing demonstration applications.The Dawning EB-class cloud storage system adopts advanced fault-tolerant architecture,efficient data fault-tolerant algorithms with user authentication and data encryption policies to deal with the"lost""wrong"and"stolen"problems of data for ensuring the reliability and safety of the EB-class storage system in the public network application environments.The Dawning EB-class Storage Laboratory taking advan-