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排序方式: 共有2390条查询结果,搜索用时 15 毫秒
51.
Giuseppe BattistoniFrancesco Broggi Markus BruggerMauro Campanella Massimo CarboniAnton Empl Alberto FassòEttore Gadioli Francesco CeruttiAlfredo Ferrari Anna FerrariMatthias Lantz Andrea MairaniM. Margiotta Cristina MoroneSilvia Muraro Katia ParodiVincenzo Patera Mauricio PelliccioniLarry Pinsky Johannes RanftStefan Roesler Sofia RolletPaola R. Sala Mario SantanaLucia Sarchiapone Massimiliano SioliGeorge Smirnov Florian SommererChristian Theis Stefania TrovatiR. Villari Heinz VinckeHelmut Vincke Vasilis Vlachoudis Joachim VollaireNeil Zapp 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2011,269(24):2850-2856
52.
Dual-Color InAs/GaSb Superlattice Focal-Plane Array Technology 总被引:1,自引:0,他引:1
Robert Rehm Martin Walther Frank Rutz Johannes Schmitz Andreas Wörl Jan-Michael Masur Ralf Scheibner Joachim Wendler Johann Ziegler 《Journal of Electronic Materials》2011,40(8):1738-1743
Within a very few years, InAs/GaSb superlattice technology has proven its suitability for high-performance infrared imaging
detector arrays. At the Fraunhofer Institute for Applied Solid State Physics (IAF) and AIM Infrarot-Module GmbH, efforts have
been focused on developing mature fabrication technology for dual-color InAs/GaSb superlattice focal-plane arrays for simultaneous,
colocated detection at 3 μm to 4 μm and 4 μm to 5 μm in the mid-wavelength infrared atmospheric transmission window. Integrated into a wide-field-of-view missile approach warning
system for an airborne platform, a very low number of pixel outages and cluster defects is mandatory for bispectral detector
arrays. Process refinements, intense root-cause analysis, and specific test methodologies employed at various stages during
the process have proven to be the key for yield enhancements. 相似文献
53.
Stijn F. L. Mertens Matthew Gara Alla S. Sologubenko Joachim Mayer Sönke Szidat Karl W. Krämer Timo Jacob David J. Schiffrin Thomas Wandlowski 《Advanced functional materials》2011,21(17):3259-3267
Dynamic core–shell nanoparticles have received increasing attention in recent years. This paper presents a detailed study of Au–Hg nanoalloys, whose composing elements show a large difference in cohesive energy. A simple method to prepare Au@Hg particles with precise control over the composition up to 15 atom% mercury is introduced, based on reacting a citrate stabilized gold sol with elemental mercury. Transmission electron microscopy shows an increase of particle size with increasing mercury content and, together with X‐ray powder diffraction, points towards the presence of a core–shell structure with a gold core surrounded by an Au–Hg solid solution layer. The amalgamation process is described by pseudo‐zero‐order reaction kinetics, which indicates slow dissolution of mercury in water as the rate determining step, followed by fast scavenging by nanoparticles in solution. Once adsorbed at the surface, slow diffusion of Hg into the particle lattice occurs, to a depth of ca. 3 nm, independent of Hg concentration. Discrete dipole approximation calculations relate the UV–vis spectra to the microscopic details of the nanoalloy structure. Segregation energies and metal distribution in the nanoalloys were modeled by density functional theory calculations. The results indicate slow metal interdiffusion at the nanoscale, which has important implications for synthetic methods aimed at core–shell particles. 相似文献
54.
Anna Jarosik Sarminala Hore Nitin Kaskhedikar Christian Pfaffenhuber Joachim Maier 《Electrochimica acta》2011,(24):14514
We have applied the concept of heterogeneous doping [1] to prepare and examine composite electrolytes, consisting of silica particles, low molecular weight polyethylene glycol solvents and lithium perchlorate salt. These “soggy sand” electrolytes combine high ionic conductivities (on the order of mS cm−1) and high Li transference numbers (typically 60–80%) with improved mechanical properties. They were characterized using differential scanning calorimetry, dc-polarization and ac-impedance spectroscopy, zeta potential measurements and viscosimetry. Oxide, size and concentration as well as solvent molecular weight were varied to better understand the influence of ceramic oxide fillers on the ion conduction in these systems. As regarding the filler content, we observe that both conductivity and transference number of Li+ start increasing already at low volume fractions of oxide particles, reach a maximum and subsequently decrease to low values. The percolating network is – after initial partial coarsening – found to be stable within the time periods of the measurements. 相似文献
55.
Thermal barrier coatings (TBCs) are successfully applied in turbines and could also protect combustion chambers in rocket engines. Apart from different loading conditions, the main difference between these applications is the substrate material, which is nickel-based for turbines and copper-based for rocket engines. To optimize the coating system, more knowledge of possible failure modes is necessary.In this work a standard coating system was applied by atmospheric plasma spraying to copper specimens. These specimens were exposed to thermal cycling with different cooling rates and to laser shock testing. A laser-cycling set-up was developed to qualify different coating systems. This set-up consists of a high-power diode laser (3 kW) which provides high heating rates to up to 1500 °C. Laser shock testing has proven to be a suitable alternative to burner rig testing.The results were different to the common failure modes for TBCs on nickel substrates as the coatings system does not fail at the interface between top coat and bond coat, but at the interface between substrate and bond coat. Two failure modes were observed: copper oxide was undermining the coatings at the substrate/bond coat-interface in the case of thermal cycling experiments, and complete delamination occurred at the same interface in the case of laser shock testing. Consequently, this interface is critical in the investigated material system. 相似文献
56.
Sarah Panowitz Jakob Barz Michael Müller Joachim Franzke Christian Oehr Thomas Hirth 《Surface & coatings technology》2011
We investigated low pressure microplasmas for surface modification. The aim of this work was to functionalize only the inner surface of a porous polymeric hollow fiber membrane with amino groups. For the surface functionalization with amino groups, especially the concentrations of NH and NH2 in the plasma gas-phase are of relevance. They can be generated for example from ammonia with admixtures of helium. A limitation is that all plasmas should have a gas temperature below the melting temperature of thermoplastic polymers.The temperature was measured in two ways; one was a fiber optical temperature sensor attached on the outside of a glass capillary, used as plasma chamber, the other one was carried out by estimation of the rotational temperature with optical emission spectroscopy from the distribution of the rotational transitions of the first negative system N2+(B2 ∑ u+→X2 ∑ g+). By using plasma excitation in the kHz range, temperatures below 50 °C were measured with the temperature sensor. With MHz-excitation, however, the temperature raised up to 200 °C. With optical emission spectroscopy, the products of decomposition of ammonia were investigated. A gas mixture with a high amount of NH molecules in the gas phase was found. By means of the investigated microplasmas, we were able to functionalize the inner surface of a porous hollow fiber with amino-groups. 相似文献
57.
58.
Relaxor/Ferroelectric Composites: A Solution in the Quest for Practically Viable Lead‐Free Incipient Piezoceramics 下载免费PDF全文
Claudia Groh Daniel J. Franzbach Wook Jo Kyle G. Webber Jens Kling Ljubomira A. Schmitt Hans‐Joachim Kleebe Soon‐Jong Jeong Jae‐Shin Lee Jürgen Rödel 《Advanced functional materials》2014,24(3):356-362
Recently developed lead‐free incipient piezoceramics are promising candidates for off‐resonance actuator applications with their exceptionally large electromechanical strains. Their commercialization currently faces two major challenges: high electric field required for activating the large strains and large strain hysteresis. It is demonstrated that design of a relaxor/ferroelectric composite provides a highly effective way to resolve both challenges. Experimental results in conjunction with numerical simulations provide key parameters for the development of viable incipient piezoceramics. 相似文献
59.
Joachim Koeser Thiago Saads Carvalho Uwe Pieles Adrian Lussi 《Journal of materials science. Materials in medicine》2014,25(7):1671-1677
Fluorides are used in dental care due to their beneficial effect in tooth enamel de-/remineralization cycles. To achieve a desired constant supply of soluble fluorides in the oral cavity, different approaches have been followed. Here we present results on the preparation of CaF2 particles and their characterization with respect to a potential application as enamel associated fluoride releasing reservoirs. CaF2 particles were synthesized by precipitation from soluble NaF and CaCl2 salt solutions of defined concentrations and their morphology analyzed by scanning electron microscopy. CaF2 particles with defined sizes and shapes could be synthesized by adjusting the concentrations of the precursor salt solutions. Such particles interacted with enamel surfaces when applied at fluoride concentrations correlating to typical dental care products. Fluoride release from the synthesized CaF2 particles was observed to be largely influenced by the concentration of phosphate in the solution. Physiological solutions with phosphate concentration similar to saliva (3.5 mM) reduced the fluoride release from pure CaF2 particles by a factor of 10–20 × as compared to phosphate free buffer solutions. Fluoride release was even lower in human saliva. The fluoride release could be increased by the addition of phosphate in substoichiometric amounts during CaF2 particle synthesis. The presented results demonstrate that the morphology and fluoride release characteristics of CaF2 particles can be tuned and provide evidence of the suitability of synthetic CaF2 particles as enamel associated fluoride reservoirs. 相似文献
60.