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  • 期刊名称:

    Materials research innovations

  • 中文名称: 材料研究创新
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  • ISSN: 1432-8917
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42条结果
  • 机译 以1-(三氯甲硅烷基)-1-(二氯硼烷基)乙烷为单源前驱体在Si / B / C / N体系中合成极其稳定的陶瓷
    摘要:A new material discovered in the Si/B/C/N system was found to remain in the amorphous state up to a very high temperature of 2000 deg.C. This material, with the composition Si2B2N5C4, is the only material in this system which does not undergo any microstructural changes until such high temperatures. Furthermore, the substance shows an extremely high resistance to oxida- tion up to 1500 deg. C. The synthesis of amorphous SizBzNsC4 was achieved by using the novel single- source precursor I -(trichlorosilyl)- l -(dichloroboryl)eth- ane (TSDE), which can be synthesized in high yields from inexpensive starting materials in a simple single pot reaction. Examination of the structural properties of the pyrolytic ceramic reveals a substructure consisting of tet- rahedrally and trigonally-planar coordinated silicon and boron, respectively. Si-C- and B-C-bonds present in the molecular precursor could not be distinguished from Si- N and B-N-bonds in the fully pyrolized ceramic. EDX and X-ray-diffraction showed the material to have a ho- mogeneous elemental distribution, and no phase separa- tion could be detected.
  • 机译 适用于倒装芯片应用的新型高性能无流量和可返修底部填充胶
    摘要:Flip-chip interconnect is the emerging technol- ogy for the high performance, high I/O (lnputs/Outputs) IC devices. Due to the thermal mismatch between the sili- con IC (CTE=2.5 ppm/0 C) and the low cost organic sub- strate such as FR-4 printed wiring board (CTE=18-22 ppm/deg. C), the flip chip solder joints experience high shear stress during temperature cycling testing. Underfill en- capsulant is used to couple the bilayer structure and is critical to the reliability of the flip-chip solder joint inter- connects. Novel no-flow underfill encapsulant is an at- tractive flip-chip encapsulant due to the simplification of the no-flow underfilling process. To develop the no-flow underfill material suitable for the no-flow underfilling process of flip-chip solder joint interconnects, we have studied and developed a series of metal chelate latent cat- alVsts for the no-flow underfill formulation. The latent catalyst has minimal reaction with the epoxy resin (cyclo- aliphatic type epoxy) and the crosslinker (or hardener) at the low temperature (
  • 机译 Ti3SiC2粉末的涨落合成与表征
    摘要:A novel fluctuation method for the synthesis of Ti3SiC2 powders was developed. The raw materials used in this process are Ti, Si, and graphite powders. Fluctuation synthesis utilized Si as in-situ liquid forming phase (additive), which was formed by heating the pow- der mixtures to 1300 deg.C and using the heat released from the exothermic reaction for Ti3SiC2 formation. The result demonstrated that the reaction time for the formation of TisSiCz was dramatically shortened using fluctuation method and the powders produced using this method contained more than twice amount of Ti3SiC2 compared to the solid reaction synthesized powders. The powders prepared by fluctuation method are fiber-like in mor- phology with dimensions of 0.8-2 pm in width and 5-1 0 pm in length. The growth direction of the fiber-like Ti3SiC2 particulate is { 1 0 1 1 } . The laitice parameters for TisSiCz were determined by a trial-and-error method and are a=3.067 A and c= 1 7.645 A.
  • 机译 雕刻薄膜-ll。实验与应用
    摘要:A report on the preparation and potential ap- plications of sculptured thin films (STFs) is presented. STFs are nano-engineered columnar thin films in which the columnar direction can made to change easily and of- ten during growth. STFs of virtually any material can be prepared through directional vapor deposition onto any surface under low adatom-mobility conditions. Colum- nar shapes, such as zig-zag, C-, S, helicoidal and super- helical, can be engineered in any sequence and with con- trolled density profiles. Although oblique deposition and the resulting anisotropic properties have been known for over a century, the general recognition that such nano- engineered morphologies can lead to unique and predict- able optical, mechanical, electrical, magnetic, thermal, and biological properties has occured only recently.
  • 机译 基于带有HTSC元件的谐振电路的敏感元件检测和刺激射频(rf)范围(〜200 khz)的脉冲电磁辐射(IEMR)
    • 作者:E. Broide;
    • 刊名:Materials research innovations
    • 1999年第4期
    摘要:The abnormally high sensitivity to low power impulse electromagnetic radiation (IEMR) systems that include a sensing element consisting of a resonant circuit with secondary coil and high-temperature superconduc- tor (HTSC) core was experimentally investigated. The core was produced using epoxied composites containing HTSC powders [YBa2Cu3Ox. and Bi(Pb)2Sr2Ca2Cu3Ox. composition]
  • 机译 光折变材料中的一束,两束和三束光学混沌和自组织效应
    摘要:Collective selforganization effects and chaos are commonly observed in optics. We describe examples in a particular kind of nonlinear optical matterial: photore- fractive crystals. In particular, we show different effects that arise when photorefractive crystal s are illuminated one laser beam, two laser beams, and three laser beams.
  • 机译 隔离的纳米相的平衡相图
    摘要:Materials processing and fabrication shows a strong trend toward manipulation of materials at ever de creasing sizes. This is especially true in microelectron ics. Once the size of a material extends below the sub- micrometer level significant changes in the properties and behavior of materials emerges. It is sometimes diffi- cult to determine if the changes observed at this nano- scale are a result of the process variables or are inherent to material because of its small size. In order to address this difficulty with regard to crystal structure and compo- sition, phase diagrams as a function of size would be particularly useful. In the present paper experimental da- ta on phase equilibria are presented as well as a thermo- dynamical analysis based on capillarity effects from sur- face curvature. The analysis and experimental data for binary phase diagrams agree with one another and show that isolated particles of less than 100 nm exhibit sub- stantial decreases in liquidus temperature, factors of more than 10 increase in solubility, and narrowing of the two-phase fields. The details of the thermodynamic mod- el and its predictive powers are presented along with a threedimensional phase diagram which has temperature- cOmpOsition-slze as its axes.
  • 机译 ZnS:MnCl2薄膜器件中共掺有MgF2或Mgs的电致发光
    摘要:We report a red shift in the light emission from thin film electroluminescent devices consisting of ZnS co-doped with MgF2 and MnCl2 as the phosphor semiconductors and Ta2O5 films as insulators. The elec- troluminescence spectrum shows two peaks at ~615 nm and at ~670 nm. The devices have a threshold of about l10 V under 50 Hz a.c driving voltage and show bright- ness over ~100 cd/m2 at l60 V. The devices are com- pared with MgS co-doped devices which show green shifted light emission.
  • 机译 湿度和温度控制下THE族晶体的表面重建
    摘要:Surface reconstruction of TGS family single crystals has been investigated using AFM at ambient and controlled conditions. Domain boundary migration with simultaneous formation of holes at the boundary has been imaged for the first time. It is found that domain wall migration is accompanied by formation of elongat ed holes on originally negative end. Using humidity / temperature controlled AFM, holes on the positive end have been obtained with fast dehumidification while there is no such hole-formation with slow dehumidifica- tion. These observations provide direct evidences for a dissolution / recrystallization model accounting for hole / terrace formations. On the basis of this work, it is further proposed that the hole-formation upon the fast dehumidi- fication can be ascribed by mass transfer limitation (ki- netic control). On the contrary, with a slow dehumidifi- cation rate, the same crystal plane would resume a flatten termination to reduce the total surface energy (thermody- namic control).
  • 机译 凹c换能器
    摘要:A new type of cymbal transducer, called the concave cymbal, has been developed to increase the pressure tolerance and reliability of the transducer under high hydrostatic pressure. The main feature of the new design is a lead zirconate titanate ceramic ring sand- wiched between two concave metal endcaps. It shows much improved pressure performance and can withstand a pressure of up to 6 MPa while maintaining high effec- tive hydrostatic piezoelectric coefficients. When incorpo- rated into a planar array with a radiating area of 5.5 cm x 5.5 cm and weight of only 30 g, a transmitting voltage response of around 125 dB re I mu Pa/V @ I m was obtained over a frequency range between 20 and 50 kHz.
  • 机译 用于热释电应用的PCLT / P(VOF-TrFE)0-3纳米复合薄膜
    摘要:Nanocrystalline calcium and lanthanum modi- fied lead titanate (PCLT) powder was prepared by a sol- gel process followed by annealing at 850 deg. C. 0-3 nano- composite thin films of PCLT powder dispersed in a vi- nylidene fluoride /trifluoroethylene (P(VDFTrFE)) co- polymer matrix were fabricated on glass substrates using the spin-coating technique. The permittivity, pyroelectric coefficient, specific heat and pyroelectric figures-of-mer- it were measured as functions of the volume fraction of ceramic for pi up to 0. 16. Single-element pyroelectric sensors with PCLT/P(VDF-TrFE) nanocomposites as the sensing elements were fabricated and characterized. The voltage and current responsivities Rv and Ri, of the sen- sors were measured as functions of frequency and found to agree well with the calculated values. Since the pyro- electric coefficients of PCLT and P(VDF-TrFE) have like signs while the piezoelectric coefficients have opposite signs, the poled composite has high pyroelectric but low piezoelectric activity, thereby reducing the vibration-in- duced electrical noise in pyroelectric sensor applications.
  • 机译 适用于传感器和执行器应用的新型压电陶瓷和复合材料
    • 作者:Ahmad Safari;
    • 刊名:Materials research innovations
    • 1999年第5期
    摘要:Novel piezoelectric ceramic, and ceramic polymer composite structures were fabricated by solid freeform fabrication (SFF) for sensor and actuator appli- cations. SFF techniques including: Fused Deposition of Ceramics (FDC), and Sanders Prototyping (SP) were uti- lized to fabricate a variety of complex structures directly from a computer aided design (CAD) file. Many novel and complex composite structures including volume fraction gradients (VFG), staggered rods, radial and curved composites, and actuator designs such as tubes, spirals and telescoping were made using the f1exibility provided by the above processes. Radial composites with various connectivities in the radial direction were made for towed array applications. VFG's were incorporated into some of these designs, with the ceramic content de- creasing from the center towards the edges. Many new designs are also being used to manufacture high authori- ty actuators utilizing the FDC technique. The telescoping actuation of the device is the summation of actuation of all individual tubes making of the actuator, therefore, in- creasing the number of the tubes which are the driving component of the actuator will further enhance the dis- placement. The design, fabrication and electromechani- cal properties of these sensor and actuator structures are discussed in this paper.
  • 机译 TGS单晶的高阶铁性
    摘要:It follows from symmetry consideration that ferroelectrics should possess ferroelastoelectric proper- ties also. The form of ferroelastoelectric domains of uni- axial upuren ferroelectric triglycine sulphate (TGS) is determined. The effects of the influence of uniaxial me- chanical pressure on dielectric hysteresis loops of TGS single crystals are observed. Pressure applied in y-direc- tion decreases height of saturated hysteresis loops (case of high ac-voltage) and increases height of non-saturated loops (case of low ac-voltage). In both cases coercitive field decreases with the pressure increase. Such a behay- ior may be connected with ferroelastoelectric properties of TGS crystals when uniaxial pressure produces favor- able conditions on the domain wall motion.
  • 机译 薄型,低频,高排量执行器面板
    摘要:An advanced type of thin, high displacement, low frequency actuator panel is being developed for in- air active vibro-acoustic control applications. The 10 cmx l0 cm actuator panel consists of cymbal-type flextensional sub-elements placed mechanically and electrically in parallel with each other between two stiff cover plates. The total thickness of the actuator panel is 6.35 mm. Two panel designs are currently under investi- gation. One consists of sixty-four 127 mm diameter cymbals in an 8 x 8 square arrangement. It is intended for use in the frequency band from 1 kHz to 10 kHz. The other panel has sixteen 25.4 mm diameter elements in a 4x4 square configuration and is designed for use below l kHz. Laser Doppler velocimetry (LDV) measurements show peak displacements on the order of 1 mu m or more are obtained when driving the panels at one Volt at their respective resonance frequencies .
  • 机译 压电细纤维复合材料-压电行为的初步证据
    摘要:The integration of functional components into composite materials is still a challenge for materials sci- ence. The integrated components themselves acting as sensor and/or as actuator should not interfere with the excellent mechanical properties of fiber-reinforced com posite materials. Using this approach the implementation of “one-dimensional”geometries like fibers with small diameters is recommended. Thin fibers consisting of piezoelectric materials like PZT are among the promis- ing candidates offering the sensor/actuator coupling. Sol- gel processing is useful for fabricating PZT fibers thin enough to behave flexibly. Therefore, they offer the op- portunity to make composite materials adaptive while maintaining the structural conformity. Sol-gel derived high-quality PZT fibers with diameters smaller than 30 mu m have been successfully integrated into planar fiber architectures. Within them the fibers are oriented uni-di- rectionally. These architectures are embedded with inter- digital electrodes. After embedding the fiber/electrode architectures within glass flber-reinforced polymers the fibers can be poled and become piezoelectric. The result- ing structures were suitable to be tested as adaptive com- ponents. It has been demonstrated that such structures can detect impacts and tensions. They can also be driven actively leading to a vibration of the structure.
  • 机译 改性Tazos薄膜的增强介电性能
    摘要:Tantalum oxide (Ta2O5) is a promising high dielectric constant material for the DRAM applications because of its ease of integration compared to other com- plex oxide dielectrics. The dielectric constant and ther- mal stability characteristics of bulk Ta2O5 samples were reported to enhance significantly through small substitu- tions of Al2O3. However, this improvement in the dielec- tric constant of (l-x)Ta2O5-xAl2O5 is not clearly under- stood. The present research attempts to explain the high- er dielectric constant of (1-x)Ta2O5-xAl2O5 by fabricat- ing thin films with enhanced dielectric properties. A higher dielectric constant of 42.8 was obtained for 0'gTa2O5-0.1 AI2O5 thin fllms compared to that reported for pure Ta2O5 (25-30). This increase was shown to be closely related to a-axis orientation. Pure Ta2O5 thin films with similar a-axis orientation also exhibited a high dielectric constant of 5l .7, thus confirming the orienta- tion effect. The leakage current properties and the reli- ability characteristics were also found to be improved with Al2O5 addition.
  • 机译 溶胶-凝胶法从无碱金属前体中析出BaTio3晶体的温度演化
    • 作者:K.M.S. Khalil;
    • 刊名:Materials research innovations
    • 1999年第5期
    摘要:Bulk structure and surface texture of BaTiO3 materials synthesized at low temperature using solgel technique have been investigated. The materials were produced by the pyrolysis of an xerogel precursor of the tentative formula BaTiO3-x(CH3COO)2x, which was pre- pared using 1 : I molar ratio of barium acetate and titani- um oxyacetate solution. The present method avoids us- ing alkali-metal hydroxides (as a hydrolyzing agent), and thus produces an alkali-metal free precursor. The decom- position course of the xerogel at the onset of formation of crystalline BaTiO3 was probed applying thermogravi- metry (TG), differential scanning calorimetery (DSC), Fourier-transform infrared spectroscopy (FTIR), and X- ray diffraciion (XRD) techniques. Resulis indicated that most of the precursor weight loss occurs below 400 deg.C, with the formation of titania rich intermediates. Howev- er, it was not until the temperature reached > 600 de.C that well crystallized BaTiO3 was produced. The specific sur- face area and porosity were assessed for BaTiO3 pro duced at 600-1000 deg C using Nz adsorption at liquid N2 temperature.
  • 机译 低损耗,可调介电材料取得突破性进展
    摘要:Low loss. tunable dielectric materials are im- portant for phased array antenna and other device appli- cations. Various composites of barium strontium titani- um oxide (BSTO) combined with other nonelectrically active oxide ceramics have been formulated for such us- es. The dielectric constant and the loss tangents of these composites have been reduced to enhance the overall im- pedance matching and thereby lowering the overall in sertion loss of the device. The material has been fabricat ed in bulk ceramic, thick film, and thin film form to ad- dress a broad range of frequency applications. The mate- rial fabrication methods and the electronic properties of these composites will be discussed in this article.
  • 机译 气功外气影响某些材料的结构和性能变化
    摘要:Temperature, time, pressure (or stress) are considered important factors in changing the Gibbs free energy and optimizing the structure and properties of materials during materials processing. The effects of some other variables, including the magnetic field, elec- trical field, electromagnetic and ultrasonic radiation, and chemical reactions have also been well characterized. These factors have been widely applied in materials pro- cessing, and their limitations have been discovered. Thus additional factors and innovative techniques are con- stantly being sought to overcome those limitations. This paper presents such an innovative technique called qigong. Three sets of materials-related experiments con- ducted by qigong doctor Yan and his collaborators are described in which for the first time the effects of qi on inanimate matter samples with no mechanical or electri- cal connection to the system are revealed on laboratory
  • 机译 用声发射法研究铁相边界
    摘要:By the acoustic emission, dilatometric and op- tic methods the phase transitions have been investigated in PbTiO3, PbZrO3 and PbHfO3 ferroelectric crystals. By the quantities of the acoustic emission activity the related coherence of the phase boundaries have been appraised. In general case the distribution on the transitions by co- herence of the boundaries between the transforming phases in perovskite-type crystals are following: para- electric-ferroelectric, paraelectric-antiferroelectric, ferro- electric-antiferroelectric, antiferroelectric-antiferroelec- tric. The received results have been discussed general- ized in order of the similarity between the ferroelectric and martensitic phase transitions. It is shown, that acous- tic emission method would be to apply for identiflcation of the phase transition type in the multiaxial ferroic crys- tals fruitful .
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