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。     

制粉工艺对BaTiO3粉体理化性能的影响

本文用化学共沉淀法制备BaTiO3超细粉,实验中分别采用氢氧化钠和草酸作沉淀剂。实验发现,采用不同的沉淀剂均能制出具有四方晶相的BaTiO3粉体,但其所含微量成分有所不同,粉体粒度分布有较大差别。通过对粉体进行半导化处理,发现用氢氧化钠作沉淀剂时不易半导化,且其烧结性能及机械性能较差,而用草酸作沉淀剂所得的粉体易半导化,且具有较好的烧结性能和机械性能。     

Sol Gel法制备PZT粉体的工艺研究

以丙醇锆(C12H28O4Zr)、醋酸铅(Pb(CH3COO)2.3H2O)、异丙醇钛(Ti{OCH(CH3)2}4)为原料,采用改进的溶胶-凝胶(Sol-Gel)工艺,研究了不同的热处理制度对于Pb(Zr0.52Ti0.48)O3粉体的物相形成、晶粒尺寸及颗粒分散度等的影响。实验结果表明,Sol-Gel法制备PZT粉体,预结晶温度段,改变烧结时间,对于粉体颗粒的尺寸影响不大;结晶温度段,改变结晶时间或结晶温度,会对颗粒尺寸产生较大的影响。     

制粉工艺对BaTiO_3粉体理化性能的影响

本文用化学共沉淀法制备 Ba Ti O3超细粉 ,实验中分别采用氢氧化钠和草酸作沉淀剂。实验发现 ,采用不同的沉淀剂均能制出具有四方晶相的 Ba Ti O3粉体 ,但其所含微量成分有所不同 ,粉体粒度分布有较大差别。通过对粉体进行半导化处理 ,发现用氢氧化钠作沉淀剂时不易半导化 ,且其烧结性能及机械性能较差 ,而用草酸作沉淀剂所得的粉体易半导化 ,且具有较好的烧结性能和机械性能。     

共沉淀法制备PDP用红色荧光粉(Y, Gd)BO3:Eu3+的正交实验研究

以Y2O3,Gd2O3,Eu2O3和硼酸为原料,草酸为沉淀剂,采用共沉淀法合成了PDP用红色荧光粉(Y, Gd)BO3:Eu3+.同时,利用正交实验探讨了合成工艺条件对荧光粉相对发光强度的影响.实验确定了制备PDP用红色荧光粉(Y, Gd)BO3:Eu3+的优化工艺条件:沉淀剂/金属离子总量为1.2:1;pH=8;离子混合超声20 min;沉淀超声1 h;650 ℃预烧1 h;950 ℃烧结2 h.采用PDP真空紫外测试系统、X射线衍射仪、环境扫描电镜对荧光粉进行了表征.结果表明:在优化工艺条件下所制备的荧光粉为六方晶系,空间群为P63/m ,平均粒径约为300 nm.     

共沉淀法制备PZT粉体及性能研究

采用共沉淀法,利用Pb(Ac)2.3H2O、ZrOCl2.8H2O、TiCl4为原料,以浓氨水为沉淀剂,聚乙二醇(PEG)为表面活性剂,正丁醇为助溶剂。经实验确定的最佳工艺条件是:反应物浓度为1 mol/L,反应物配比为r[Pb(Ac)2]:r[ZrOCl2]:r[TiCl4]:r[NH3.H2O]=2:1.04:1:12,盐酸浓度为0.04~0.08 mol/L,PEG浓度为0.004~0.006 mol/L,反应温度为常温,反应时间为1~2 h。能够制备出粒度均匀、分散性好的纳米PZT超细粉体,粒径为10~30 nm。650℃煅烧保温2 h,已完全合成为单一晶型钙钛矿PZT固溶体。1 150℃烧结保温2 h,然后对此压电陶瓷的相对介电常数3Tε3/0ε、介电损耗tanδ、压电应变常数d33、机电耦合系数kp、机械品质因数Qm、体积密度ρ、居里温度TC等主要性能进行了测试;对显微结构及相组成进行了分析,实验数据表明可得到一种综合性能优良的压电材料。     

应用于FRAM的集成铁电电容的研究

集成铁电电容的制备是铁电存储器的关键工艺之一。该文采用射频(RF)磁控溅射法在Pt/Ti/SiO2/Si制备Pb(Zr,Ti)O3(PZT)薄膜,上下电极Pt采用剥离技术工艺制备,刻蚀PZT薄膜,形成Pt/PZT/Pt/Ti/SiO2/Si集成电容结构,最后高温快速退火。结果表明,这种工艺条件可制备性能良好的铁电电容,符合铁电存储器对铁电电容的要求。     

Ce：YIG粉体的制备及性能研究

本实验采用共沉淀法制备Ce:YIG粉体。通过对反应体系的pH值的研究，确定了反应的最佳pH值范围为8－9，得到了颗粒分布均匀的粉体。经电子探针微区分析，粉体的组分与实验设计的配方相吻合。粉体在不同的温度条件下进行烧结实验，经XRD分析证实，YIG的成相温度在650℃附近。可以认为，用共沉淀法制备的Ce:YIG粉体化学活性好，烧结温度低。     

一种制备纳米Fe_3O_4的新方法及其磁性能研究

在正丙醇–水体系中,以NaOH为沉淀剂,用共沉淀法制备了纳米Fe3O4粒子,并用TEM和XRD对其进行了表征。考察了制备过程中工艺参数对Fe3O4颗粒大小的影响,并对影响机理进行了探讨。结果表明:纳米Fe3O4的平均粒径约为15nm;其饱和磁化强度可达73.34Am2/kg,比用水热法(42Am2/kg)和共沉淀法(60Am2/kg)制备的Fe3O4纳米粒子的要高。     

采用金属有机化合物热分解法研制锆钛酸铅薄膜

详细研究了采用金属有机化合物热分解法制备锆钛酸铅Pb（Zr0.53Ti0.47）O3铁电薄膜的工艺,讨论了影响PZT薄膜相结构的因素。     

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.     

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.     

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.     

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.     

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.     

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