排序方式: 共有18条查询结果,搜索用时 15 毫秒
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Y. Liu B. S. Senturk J. V. Mantese M. Aindow S. P. Alpay 《Journal of Materials Science》2011,46(20):6563-6570
A study of the microstructure, development of contact resistance during oxidation, and abrasive wear behavior for a Ni–18 at.%Ru
alloy is presented in this article. It is shown that the alloy can be solutionized and aged, resulting in a fine lamellar
mixture of FCC α-Ni and HCP β-Ru phases. Upon oxidation in air for 400 h, the measured contact resistance of the alloy is
two orders of magnitude lower than that of pure Ni after 400-h oxidation. This behavior results from the formation of a low-resistivity
rutile RuO2 scale on the β phase lamellae, which gives conducting pathways through the insulating NiO scale that forms on the α phase.
After an initial run-in period, the steady-state abrasive wear rate measured for the Ni–Ru alloy is an order of magnitude
less than that of pure Ni. Since the micro-cutting and flaking wear mechanisms are the same, the differences in the wear rates
are ascribed to the presence of the well-dispersed hard Ru-rich β phase. The combination of a low-resistivity self-healing
native oxide scale and good wear properties makes the alloy an excellent candidate for electrical contact applications. 相似文献
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Zhong S Alpay SP Roytburd AL Mantese JV 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2006,53(12):2349-2356
Ferroelectric multilayers and superlattices have gained interest for dynamic random access memory (DRAM) applications and as active elements in tunable microwave devices in the telecommunications industry. A number of experimental studies have shown that these materials have many peculiar properties which cannot be described by a simple series connection of the individual layers that make up the heterostructures. A thermodynamic analysis is presented to demonstrate that ferroelectric multilayers interact through internal elastic, electrical, and electromechanical fields and the strength of the coupling can be quantitatively described using Landau theory of phase transformations, theory of elasticity, and principles of electrostatics. The theoretical analysis shows that compositional variations across ferroelectric bilayers result in a broken spatial inversion symmetry that can lead to asymmetric thermodynamic potentials favoring one ferroelectric ground state over the other. Furthermore, the thermodynamic modeling indicates that there is a strong electrostatic coupling between the layers that leads to the suppression of ferroelectricity at a critical paraelectric layer thickness for ferroelectric-paraelectric bilayers. This bilayer is expected to have a gigantic dielectric response similar to the dielectric anomaly near Curie-Weiss temperature in homogeneous ferroelectrics at this critical thickness. 相似文献
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Abstract Both direct current (d.c.) and alternating current (a.c.) conductivity measurements were undertaken on lead zirconate titanate (PZT) films synthesized by laser ablation deposition. Direct current (I) displayed an initial time dependence of the form I ∝ t?γ (γ ∝ 0.5–1.0). The possible reasons for this time dependence are discussed. At lower temperatures, the a.c. electrical conductivity shows a frequency dependence of the form σ ∝ ω′ which is explained as electrical charge hopping. At higher temperatures, the d.c. component of electrical conductivity becomes dominant, and is accompanied by a strong low frequency dispersion of the dielectric constant. The results are compared to published data on conductivity in SrTiO3, and discussed in terms of the latest theories for dielectric response of materials. 相似文献
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Y. Liu L. C. Zhang B. S. Senturk J. V. Mantese S. P. Alpay M. Aindow 《Journal of Materials Science》2012,47(15):5701-5705
The precipitation of β-Ru phase upon aging of a solutionized Ni–18 at.% Ru alloy was studied by X-ray diffraction and electron microscopy. It was shown that: the β phase forms by discontinuous lamellar decomposition from nucleation sites on α grain boundaries; the phases exhibit well-defined orientation relationships; and the hardness of the alloy correlates strongly with the extent of decomposition. The implications for the use of heat treatment to control the microstructure and mechanical properties of the alloy are discussed. 相似文献
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Semenov A.A. Karmanenko S.F. Kalinikos B.A. Srinivasan G. Slavin A.N. Mantese J.V. 《Electronics letters》2006,42(11):641-642
A novel electric and magnetic field tunable microwave resonator with a yttrium iron garnet and barium strontium titanate layered structure is investigated. The measured characteristics at 3.6 GHz, corresponding to the proximity of magnetic and dielectric resonance modes, show a broadband electrical tunability. A tuning range of 1.5% of the central resonance frequency is obtained for nominal electric fields. 相似文献
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Mantese J.V. Micheli A.L. Schubring N.W. Catalan A.B. Soch K.L. Ng K. Klapper S.H. Lopez R.J. Lung G. 《Electron Devices, IEEE Transactions on》1993,40(2):320-324
Potassium tantalum niobate (KTN) films, 10-μm thick, with a nominal Curie temperature of -20°C were formed on polished platinum-coated sacrificial yttria substrates by metalorganic deposition (MOD). These KTN films were used to fabricate focal plane arrays consisting of 128×128 pixels with each pixel on 50-μm centers and 50-μm2. Using f /1 optics and a 2.5-V/μm 2 detector bias, a noise equivalent temperature (NEΔT) of 0.65°C was obtained for the best 1% of the pixels when the detector and blackbody source operated at 25°C 相似文献
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