Effective electroelastic moduli of 3-3(0-3) piezocomposites

In a high volume fraction particle-loaded piezocomposite, some ferroelectric particles appear to be in contact, as in a 3-3 connectivity material; others are isolated in the polymer matrix, as in a pure 0-3 connectivity material. Such a material can be considered as a composite of composites characterized by a 3-3(0-3) connectivity. This paper follows two others that have described a matrix method to calculate all of the effective parameters of pure 0-3 and 3-3 connectivity piezocomposites. These previous models are used to obtain the effective properties of a 3-3(0-3) composite. A proportion of 0-3 connectivity in the composite is introduced, and the effective properties are studied as a function of this proportion. Experimental results compared with these predictions show that the model allows an evaluation of the proportion of 0-3 connectivity through the analysis of the electromechanical performance of the composite samples.     

Phase diagrams of the ternary liquid systems [Ce(NO3)3(TBP)3]-C10H22-[UO2(NO3)2(TBP)2] and [Ce(NO3)3(TBP)3]-C10H22-[Th(NO3)4(TBP)2] and of the quaternary liquid system [Ce(NO3)3(TBP)3]-C10H22-[UO2(NO3)2(TBP)2]-[Th(NO3)4(TBP)2]

The phase diagrams of the ternary liquid systems [Ce(NO₃)₃(TBP)₃]-C₁₀H₂₂-[UO₂(NO₃)₂(TBP)₂] and [Ce(NO₃)₃(TBP)₃]-C₁₀H₂₂-[Th(NO₃)₄(TBP)₂] and of the quaternary liquid system [Ce(NO₃)₃(TBP)₃]-C₁₀H₂₂-[UO₂(NO₃)₂(TBP)₂]-[Th(NO₃)₄(TBP)₂] at T = 298.15 K are constructed. The phase diagrams are characterized by areas of homogeneous solutions and of two-phase liquid systems (systems with phase separation), with one phase (I) enriched in [Ce(NO₃)₃(TBP)₃], [Th(NO₃)₄(TBP)₂], and [UO₂(NO₃)₂(TBP)₂], and the other phase (II), in C₁₀H₂₂. Using the data on the mutual solubility of the components in the systems under consideration and equations of the NRTL model, the parameters of intermolecular interactions and the excess Gibbs energies (G ^ex) were calculated for the binary, ternary, and quaternary systems. Passing from the ternary system [Ce(NO₃)₃(TBP)₃]-C₁₀H₂₂-[Th(NO₃)₄(TBP)₂] to the quaternary system [Ce(NO₃)₃(TBP)₃]-C₁₀H₂₂-[UO₂(NO₃)₂ (TBP)₂]-[Th(NO₃)₄(TBP)₂] does not appreciably affect the distribution of C₁₀H₂₂ between phases I and II, but leads to the redistribution of [Ce(NO₃)₃(TBP)₃] into phase II and of [Th(NO₃)₄(TBP)₂] into phase I.     

聚(苯胺-邻六氟羟基苯胺)共聚物的合成及其性能表征

采用过硫酸铵作为引发剂,通过化学氧化聚合法制备了一系列可溶性的聚(苯胺-邻六氟羟基苯胺)(PAH)的共聚物。利用傅里叶红外光谱(FTIR)、核磁共振氟谱(19F-NMR)、核磁共振氢谱(1H-NMR)、凝胶渗透色谱(GPC)、紫外光谱(UV)和场发射扫描电子显微镜(FESEM)等对共聚物的化学结构和形貌等进行了表征和分析。结果表明,邻六氟羟基苯胺(HAFIP)成功导入了共聚物主链中,共聚物的数均分子量Mn介于6.51×10~4与9.04×10~4之间。HAFIP的存在抑制了共聚物的醌式结构n→π*跃迁,随着共聚物中邻六氟羟基苯胺(HAFIP)摩尔分数的增大,共聚物形貌逐渐由纳米纤维向纳米颗粒变换。与聚苯胺难于溶解于一般有机溶剂不同的是,当邻六氟羟基苯胺(HAFIP)的摩尔分数超过0.5时,共聚物可以完全溶解于四氢呋喃、乙醇、N-甲基吡咯烷酮、N,N-二甲基甲酰胺等有机溶剂中,表明HAFIP的导入,可以大幅改善聚苯胺的溶解性能,从而扩展聚苯胺的应用范围。     

Properties of epitaxial, (001)- and (110)-oriented (PbMg1/3Nb2/3O3)2/3-(PbTiO3)1/3 films on silicon described by polarization rotation

Epitaxial (PbMg_1/3Nb_2/3O₃)_2/3-(PbTiO₃)_1/3 (PMN-PT) films with different out-of-plane orientations were prepared using a CeO₂/yttria stabilized ZrO₂ bilayer buffer and symmetric SrRuO₃ electrodes on silicon substrates by pulsed laser deposition. The orientation of the SrRuO₃ bottom electrode, either (110) or (001), was controlled by the deposition conditions and the subsequent PMN-PT layer followed the orientation of the bottom electrode. The ferroelectric, dielectric and piezoelectric properties of the (SrRuO₃/PMN-PT/SrRuO₃) ferroelectric capacitors exhibit orientation dependence. The properties of the films are explained in terms of a model based on polarization rotation. At low applied fields domain switching dominates the polarization change. The model indicates that polarization rotation is easier in the (110) film, which is ascribed to a smaller effect of the clamping on the shearing of the pseudo-cubic unit cell compared to the (001) case.     

Superplasticity in Aluminium Brass(HAl 66-6-3-2)

1.IntroductionSuperplasticity is not merely a specialphenomenon for certain specific alley,but isone of the intrinsic properties of metallicmaterials[1].When the internal and externalconditions are suitable,superplasticity ofmetal materials will be presented.     

0.08Pb(Fe1/3Sb2/3)O3-yPbTiO3-(1-0.08-y)PbZrO3压电陶瓷性能研究

合成了钙钛矿结构的0.08Pb(Fe1/3 Sb2/3)O3-yPb-TiO3-(1-0.08-y)PbZrO3三元系压电陶瓷材料,测量并计算了不同y值时的压电常数(d33)、机电耦合系数kp、k33)、机械品质因数(Qm)以及极化前后的介电常数(εT33/ε0),对实验现象进行了简单的讨论,得出一些有益的结论;实验结果表明当选取合适的y值时可以获得压电性能良好的压电材料,如y=0.45时材料的平面机电耦合系数kp、纵向机电耦合系数k33和压电常数d33分别达到0.64×10-12C/N、0.72×10-12C/N和365×10-12C/N.     

Crosslinking of tissue-derived biomaterials in 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC)

In contrast to bifunctional reagents such as glutaraldehyde or polyfunctional reagents such as polyepoxides, carbodiimides belong to the class of zero-length crosslinkers which modify amino acid side-groups to permit crosslink formation, but do not remain as part of that linkage. The authors have compared the effects of 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC) and glutaraldehyde (the de facto industrial standard crosslinker) on the hydrothermal, biochemical, and uniaxial mechanical properties of bovine pericardium. EDC crosslinking was optimized for maximum increase in collagen denaturation temperature using variables of pH, concentration, and ratio of EDC to N-hydroxysuccinimide (NHS): a reagent for formation of activated esters. EDC and glutaraldehyde crosslinked materials were subjected to hydrothermal denaturation tests, biochemical degradation by enzymes (collagenase, trypsin) and CNBr, amino acid analysis for unreacted lysine, and to high strain rate mechanical tests including: large deformation stress-strain studies (0.1 to 10 Hz), stress relaxation experiments (loading time 0.1 s) and small deformation forced vibration (1 and 10 Hz). A protocol for EDC crosslinking was developed which used 1.15% EDC (2:1 EDC:NHS) at pH 5.5 for 24 h. The increase in denaturation temperature for EDC (from 69.7±1.2°C to 86.0±0.3°C) was equivalent to that produced by glutaraldehyde (85.3±0.4°C). Both treatments equivalently increased resistance to collagenase and CNBr degradation; however, after denaturation, the EDC-treated tissue was slightly more resistant to collagenase, and markedly more resistant to trypsin. EDC-treated materials were more extensible and more elastic than glutaraldehyde-treated materials. Despite the differences in crosslinking mechanism, EDC and glutaraldehyde-treated materials are very similar. Subtle but intriguing differences in biochemical structure remain to be investigated.     

Crystal structure and dielectric properties of Ca(0.85)Nd(0.1)TiO(3) - LnAlO(3) ceramics

The microwave dielectric properties of Ca(0.85)Nd(0.1)TiO(3) - LnAlO(3) (Ln = Sm, Gd, Dy, Er) ceramics are investigated in this paper. The structural characteristics of the specimens were evaluated by Rietveld refinement of Xray diffraction (XRD) patterns and high-resolution transmission electron microscopy (HRTEM). Solid solution limits were dependent on the ionic radius of Ln(3+) ions. With the decrease of the ionic radius of the Ln(3+) ions, the thermal stability of the resonant frequency decreases. This can be attributed to the increased level of oxygen octahedral distortion caused by the increase in the B-site bond valence in the ABO(3) perovskite structure. The dielectric constant (K) and the quality factor (Qf) of the specimens were dependent on the polarizability and grain size, respectively.     

Complete set of material properties of [011](c) poled 0.24Pb(In(1/2)Nb(1/2))O(3)-0.46Pb(Mg(1/3)Nb(2/3))O(3)-0.30PbTiO(3) single crystal

A complete set of elastic, piezoelectric, and dielectric constants of [011](c) poled multidomain 0.24Pb(In(1/2)Nb(1/2))O(3)-0.46Pb(Mg(1/3)Nb(2/3))O(3)-0.30PbTiO(3) ternary single crystal has been determined using resonance and ultrasonic methods and the temperature dependence of the dielectric permittivity has been measured at 3 different frequencies. The experimental results revealed that this [011](c) poled ternary single crystal has very large transverse piezoelectric coefficient d(32) = -1693 pC/N, transverse dielectric constant ε(11)/ε(0) ~ 7400 and a high electromechanical coupling factor k(32) ~ 90%. In addition, its coercive field is 2 times of that of the corresponding binary 0.7Pb(Mg(1/3)Nb(2/3))O(3)-0.30PbTiO(3) single system with much better temperature stability. Therefore, the crystal is an excellent candidate for transverse mode electromechanical devices.     

Highly selective ratiometric fluorescence determination of Eu3+ ion based on (4E)-4-(2-phenyldiazenyl)-2-((E)-(2-aminoethylimino)methyl)phenol

(4E)-4-(2-phenyldiazenyl)-2-((E)-(2-aminoethylimino)methyl)phenol (PAMP) was synthesized for the first time and used as a ratiometric fluorescent chemosensor for recognition of Eu³⁺ ions in acetonitrile solution. PAMP shows a fluorescent emission at 536 nm. When it forms a complex with Eu³⁺ ion, two new fluorescent enhancements at 418 and 496 nm appeared. In acetonitrile solution, the blue shift of fluorescent emission upon europium binding is due to the formation of a 1:1 metal ligand complex. The chemosensor shows a linear response toward Eu³⁺ in the range of 8.3 × 10^? 8 M to 8.3 × 10^? 6 M. The new fluorescent probe exhibits high selectivity toward Eu³⁺ ions over a large number of interfering cations.     

A 3.7 MHz phased array probe using 0.91Pb(Zn(1/3)Nb(2/3))O(3)-0.09PbTiO(3 )

A novel 128-channel phased array probe for echocardiography with a center frequency of 3.7 MHz using 0.91Pb(Zn(1/3)Nb(2/3))O(3)-0.09PbTiO(3 ) (PZN-9%PT) single crystal has been fabricated to realize greater sensitivity and broader bandwidth properties. The echo amplitude of the PZN-9%PT single-crystal probe is about 5 dB higher than that of the conventional lead airconate titanate (PZT) ceramic probe, and the fractional bandwidth is about 25 percentage points broader. The quality of B mode images obtained by the PZN-9%PT probe satisfies the performance of the two types of conventional PZT ceramic probes that have center frequencies of 2.5 and 3.75 MHz. At the reference frequency of 3 MHz, the Doppler sensitivity of the PZN-9%PT probe is about 5 dB higher than that of the 3.75 MHz PZT probe; the blood flow of a pulmonary vein in a hard-to-image patient is much more clearly imaged than in the case of using the PZT probe. These superior images are attributable to the use of sufficiently large PZN-9%PT single crystals obtained by the self-flux method.     

Complete set of material properties of single domain 0.24Pb(In(1∕2)Nb(1∕2))O(3)-0.49Pb(Mg(1∕3)Nb(2∕3))O(3)-0.27PbTiO(3) single crystal and the orientation effects

Multidomain relaxor-based single crystals have intrigued the enthusiasm of many researchers due to their superior electromechanical properties. In order to understand the physical origin of multidomain properties, one must know the complete set of material coefficients in single domain state. Previous published single domain data were all measured under bias because single domain state is unstable. Here, we report a set of single domain data without bias for rhombohedral 0.24Pb(In(1∕2)Nb(1∕2))O(3)-0.49Pb(Mg(1∕3)Nb(2∕3))O(3)-0.27PbTiO(3) single crystal. Comparing rotated coefficients from single domain data with measured multidomain material coefficients, we concluded that the orientation effects account for more than 90% of the observed multidomain properties.     

Forty-channel phased array ultrasonic probe using 0.91Pb(Zn(1/3 )Nb(2/3))O(3)-0.09PbTiO(3) single crystal

A 0.91Pb(Zn(1/3)Nb(2/3))O(3)-0.09PbTiO (3) (PZN-PT) single crystal with high electromechanical coupling factor (k(33))>90% has been used to fabricate a 40-channel phased array ultrasonic probe with greater sensitivity and broader bandwidth than conventional probes. This probe has a center frequency of 3.5 MHz and an aperture of about 6.0x7.5 mm. The standard probe fabrication process was modified for PZN-PT. The dispersion of echo signals was within +/-20% of the mean value. After recovery poling, the echo amplitude of the PZN-PT single-crystal probe is 8 and 5 dB higher than that of one- and two-matching-layer PZT probes, respectively. Moreover, the fractional bandwidth of the single-matching-layer PZN-PT probe is broader than that of the two-matching-layer PZT probes. The PZN-PT single crystals provide great improvements in the sensitivity and bandwidth of phased array probes.     

Hydrolysis-condensation kinetics of 3-(2-amino-ethylamino)propyl-trimethoxysilane

The kinetics of the hydrolysis and self-condensation reactions of 3-(2-amino-ethylamino)propyl-trimethoxysilane (DAMS) were investigated by in situ²⁹Si NMR spectroscopy using pure water and an alcoholic (80:20 w/w ethanol/water) solvent mixture as reaction media. In both media, the reactivity of the silane was strongly influenced by the pH of the medium during the initial stage of the reaction. The silanols produced by hydrolysis in water were much more stable than those produced in the alcoholic solvent mixture, the latter of which were susceptible to self-condensation, yielding siloxane bridges. The active silanol reactivity (SR), which is a simple parameter that reflects the silanol content in the solution as a function of the reaction time, was proposed for evaluating the reactivity of a solution of DAMS. SR was maintained at a good level (high silanol group concentration) when pure water was used as the reaction medium. The pH of the reaction appears to be the predominant parameter for determining the SR during the first 2 h, regardless of the reaction solvent.     

Microbial synthesis and enzymatic degradation of renewable poly[(R)-3-hydroxybutyrate-co-(R)-3-hydroxyhexanoate]

This paper reports our recent progress on a microbial system for efficient production of biodegradable copolyester of poly[(R)-3-hydroxybutyrate-co-(R)-3-hydroxyhexanoate], P(3HB-co-3HHx), with desirable copolymer compositions using genetically engineered bacteria. We have developed a fermentation technique to achieve high cell density cultivation of a recombinant Ralstonia eutropha using inexpensive soybean oil as a sole carbon source. In addition, we demonstrate that the use of polyhydroxyalkanoate (PHA) synthase (PhaC) mutants having an amino acid substitutions is able to vary the copolymer composition of P(3HB-co-3HHx) synthesized from soybean oil by the recombinant bacteria. On the other hand, it is also important to understand the enzymatic degradation process of PHA materials for establishing a method to regulate the rate of biodegradation. The enzymatic degradation process of P(3HB-co-3HHx) thin film using an extracellular PHB depolymerase has been studied by in situ atomic force microscopy in buffer solution. We demonstrate that the PHA depolymerase predominantly degrades the less-ordered molecular chain-packing regions along the crystallographic a-axis.     

A 20 MHz single-element ultrasonic probe using 0.91Pb(Zn(1/3 )Nb(2/3))O(3)-0.09PbTiO(3) single crystal

A 20 MHz single-element ultrasonic probe using 0.91Pb(Zn(1/3 )Nb(2/3))O(3)-0.09PbTiO(3) (PZN-PT 91/9) single crystal has been fabricated. The single crystal of PZN-PT 91/9 orientated to the (001) plane has longitudinal coupling factor of k(33)>90%, which is much larger than the k(33)=70 to 80% of conventional Pb(Zr(1-x),Ti(x))O(3) (PZT) based ceramics. A single crystal of PZN-PT 91/9 without inclusion or crack has been grown with dimensions of about 25x15x5 mm by the self-flux method. Because mechanical strength in the fabrication of disk transducers orientated to the (001) plane was sufficiently strong, under the same conditions as are applied to conventional PZT ceramics, a piston single-element probe with a diameter of 2.0 mm and a frequency of 20 MHz was successfully fabricated. The bandwidth of the PZN-PT 91/9 probe was 13-26 MHz, which was 4 MHz broader than that of the conventional PZT probe.