PMNT热释电陶瓷材料的制备及性能研究

用软化学法合成了驰豫型复合钙钛矿结构铁电PMNT粉体,并将制备好的粉体压制成圆片状后放入硅碳棒炉中,于1150℃下烧结成致密热释电陶瓷材料．然后用x射线粉末衍射对合成材料进行物相分析,并用扫描电镜观察了晶粒形貌特征．结果表明：烧结后的陶瓷具有很好的致密性和热释电性,其中,0．67PMN．0．33PT组分热释电陶瓷的热释电系数为4．5×10^-4C·m^-2．K^-1,探测优值Fd为3．9×10^-5Pa^-1/2。     

基于液晶调制器调制的实时测温系统

分析了一种基于基尔霍夫定律的钽酸锂(LiTaO3)热释电探测器作为接收元件的实时测温系统中,机械式调制盘对测量精度影响,提出了改变机械式调制盘对测量精度的影响的方法;介绍了液晶调制器的结构、对辐射调制的原理以及在使用过程中的优点。设计了利用液晶调制器替代机械调制器的钽酸锂热释电实时测温系统。结果表明,利用液晶调制器改进后的测温系统在给定的温度范围中,测量精度均有明显的改善,符合测量要求。     

适用于非常规工作环境中热释电型激光能量计的研制

现有的激光能量计传感器灵敏度系数都与其所处环境温度有关,在-50℃～70℃的温度范围内,灵敏度偏差较大,直接影响测量结果。为了达到消除环境温度的影响,采取在不同环境温度下对热释型能量计的灵敏度进行校准的研究方法。该校准方法与普通激光能量计的校准方法的不同之处在于对热释电型能量计进行校准时,温度由室温扩展到-50℃～70℃的温度范围。利用环境试验箱,每隔10℃固定一个温度点,进行激光能量的测量实验,得到各个温度点所对应的灵敏度修正系数,再借助最小二乘法建立起各个温度点上能量计灵敏度系数同环境温度的函数关系,从而实现了-50℃～70℃的温度范围内激光能量的准确计量。研制能直接工作于非常规工作环境下的热释电型激光能量计,对解决激光能量测量的外场需求有一定现实意义。     

Novel cyano-containing copolymers of vinyl esters for piezoelectric materials

The synthesis of a series of novel cyano-containing copolymers is described. Alternating copolymers of acrylonitrile with vinyl esters are obtained by increasing the electrophilic character of the nitrile monomers by complexation with zinc chloride. Copolymers of methyl and ethyl α-cyanoacrylates with vinyl esters are prepared using radical initiators in the presence of 7% acetic acid as inhibitor for anionic polymerization. The copolymers of methyl α-cyanoacrylate with the vinyl esters have T_g's above 140°C. Methyl vinylidene cyanide (MVCN) copolymerizes spontaneously with para-substituted styrenes to yield copolymers with high inherent viscosities and high T_g (160°C) and the copolymer of MVCN with vinyl acetate is also synthesized. The pyroelectric constants p for these polymers were measured and the values of p for the copolymers of vinyl acetate with methyl β,β-dicyanoacrylate, methyl α-cyanoacrylate, or MVCN were in the same range as the well-studied vinylidene cyanide/vinyl acetate copolymer. A higher concentration of dipoles generally results in higher T_g's and higher pyroelectric coefficients. © 1992 John Wiley & Sons, Inc.     

Thermal behavior of ferroelectric Polyamide 11 in relation to pyroelectric properties

The pyroelectric properties of oriented thin films of ferroelectric Polyamide 11 have been studied in the temperature range of −100°C up to +140°C. The temperature dependence of the experimental pyroelectric coefficient has been analyzed. Three changes of slope of the pyroelectric coefficient are observed at −20, +50, and +100°C. The origin of the lower temperature event has not yet been defined. The upper transition is attributed to chain movements in crystalline regions, and more precisely, to a crystalline phase transition. The intermediate event is close to the glass transition temperature T_g observed by DSC. It is attributed to the manifestation of the glass transition. Below T_g, the variations of the pyroelectric coefficient are very small. For higher temperatures, it increases rapidly, attesting to a major contribution of secondary pyroelectricity and dimensional effects above T_g. The breaking of hydrogen bonds occurring at the glass transition temperature observed on DSC thermograms does not affect pyroelectric properties. Pyroelectric properties are mildly reduced after annealing at temperatures up to +140°C. A comparative study of oriented ferroelectric films prepared by quenching from the melt and nonoriented slowly cooled samples has been carried out by means of DSC. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 715–723, 1999     

A novel route to perovskite lead zirconate from lead glycolate and sodium tris(glycozirconate) via the sol–gel process

A perovskite lead zirconate was synthesized, using lead glycolate and sodium tris (glycozirconate) as the starting precursors, by the sol–gel process. The obtained molar ratio Pb:Zr of PbZrO₃ was 0.9805:1. The TGA–DSC characterizations indicated that the percentage of ceramic yield was 56.4, close to the calculated chemical composition of 59.6. The exothermic peak occurred at 245.7 °C, close to the theoretical Curie temperature of 230 °C. The pyrolysis of PbZrO₃ of the perovskite phase was investigated in terms of calcination temperature and time. The structure obtained was the orthorhombic form when calcined at low temperature at 300 °C for 1 h; it transformed to the monoclinic and cubic forms of the perovskite phase at higher temperatures above the Curie temperature as verified by X‐ray data. The lead zirconate synthesized and calcined at 300 °C for 1 h has the highest dielectric constant, the highest electrical conductivity and the dielectric loss tangent of 2267, 3.058 × 10^?4 (Ω m)^?1 and 2.484 at 1000 Hz, respectively. The lead zirconate powder produced has potential applications as materials used in microelectronics and microelectromechanical systems. Copyright © 2007 John Wiley & Sons, Ltd.     

有序组装超薄膜热释电性能的优化研究

报道两亲性染料半花菁(DAEP)与隔层材料氮冠醚(NC)交替LB膜的热释电效应以及掺杂金属离子（Ba2+）对LB膜热释电性能的影响.发现所测样品的热释电系数p高达58μCm-2K-1；在频率为1kHz—100kHz的范围内，其εr和tanδ的数值分别为2.34—1.96和0.08—0.04.并讨论了不同成膜方式和掺杂金属离子Ba2+对LB膜热释电性能影响的物理机理.     

Design and thermal analysis of electrically calibrated pyroelectric detector

A finite element model was set up by ANSYS to optimize the structure of an electrically calibrated detector and simulate the thermal diffusivity. High-performance relaxor-based ferroelectric crystals were selected as the detector materials. Gold-black was selected as the black coating on the surface of the calibrated pyroelectric detector. The finite element model was set up by ANSYS and the geometry model was meshed appropriately. The optimized structure stood out from the several feasible structures. The simulation results showed that the differences of ΔT on the top surface of PMN-PT crystal between radiant and electrical heating decrease with the increase of sensitive area. The sensitive area of the detector is 10 mm × 10 mm and the entrance aperture is ∅ 8 mm. In this condition, the differences of ΔT are 1.20%. An electrically calibrated pyroelectric detector was fabricated according to the simulation results.     

外加交变电势对摩擦力影响的试验研究

对（Ｃｕ－４３Ｎｉ），（Ｃｕ－４３Ｎｉ）／ＴｉＮ和（Ｃｕ－４３Ｎｉ）／ＮｉＰ这３种摩擦副产生的热电势信呈作了频谱分析，并对三者进行了施加不同特性的交变电势信号的摩擦试验。结果表明，将交变电势旋加于３种摩擦副的均可降低摩擦力，降低程度与所加电势的幅值、波形及频率特性有关。     

The Influence of Porosity on the Electromechanical and Pyroelectric Properties of Ca-Modified PbTiO3 Thin Films

The properties of Pb_1-xCa_xTiO₃ (x = 0–30) thin films for electromechanical and pyroelectric applications can be further improved if porous, low-dielectric constant layers are being used. The electric field dependent strain, piezoelectric coefficient, pyroelectric coefficient and the pyroelectric figure of merit were evaluated as a function of the Ca-content and relative density of the thin films. The heating-rate during the final anneal was observed to be the controlling parameter for the evolution of either dense or porous microstructures. Both 2-methoxyethanol and 1,3-propanediol based solution precursors were used for spin-coating platinized Si₃N₄/SiO₂/Si wafers. Microstructure-property relationships and electrical properties concerning the domain mobility were examined.