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111.
Development of Ferroelectric Aerogels 总被引:1,自引:0,他引:1
Löbmann Peer Glaubitt Walther Geis Stefan Fricke Jochen 《Journal of Sol-Gel Science and Technology》1999,16(1-2):173-182
For ultrasonic applications in gases porous piezoelectric transducers with low acoustic impedances are required. Highly porous piezoceramics can be prepared by sol-gel processing, supercritical drying and subsequent firing. These PT and PZT aerogels are obtainable as crystalline monoliths with porosities up to 70 vol%. In this paper the influence of sol-gel-synthesis, stoichiometry, drying conditions and heat treatment on the material properties are reviewed.Lowering the coercive field strength by dopants is necessary in order to facilitate the polarization of highly porous PZT-ceramics. New results show that the introduction of 2 mol% neodymium is possible in the sol-gel synthesis of the aerogel precursor. Most structural properties of the resulting PbNd0.02Zr0.53Ti0.47O3 aerogels are similar to those of the undoped material. 相似文献
112.
P. Kürpick H. J. Lüdde W. -D. Sepp B. Fricke 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1992,25(1):17-21
Using the independent particle model as our basis we present a scheme to reduce the complexity and computational effort to calculate inclusive probabilities in many-electron collision system. As an example we present an application toK?K charge transfer in collisions of 2.6 MeV Ne9+ on Ne. We are able to give impact parameter-dependent probabilities for many-particle states which could lead toKLL-Auger electrons after collision and we compare with experimental values. 相似文献
113.
114.
Y. J. Yu J. G. Li C. Z. Dong X. B. Ding S. Fritzsche B. Fricke 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,44(1):51-56
Multi-configuration Dirac-Fock method (MCDF) is employed to
calculate excitation energies, ionization potentials and oscillator
strengths for all neutral and up to 5 times ionized species of
element Uub, as well as the homologue elements Zn, Cd and Hg. On
the basis of not too extended MCDF calculations, we studied some peculiar
properties of element Uub resulting from its stronger relativistic
and electron correlation effects. Using an extrapolative scheme,
improved ionization potentials of Uub were obtained with
an uncertainty of less than 0.5 eV. Furthermore, we calculated the
low-lying resonance excitation energies, absorption oscillator
strengths and the first ionization potential for Hg and Uub using
large scale MCDF calculations, which improved the uncertainty of
the excitation energies to less than 0.25 eV for element Hg. We hope
that such calculations yield good results for element Uub. 相似文献
115.
The influence of relativistic effects on properties and volatility of the group-8 tetroxides MO4, where M=Ru, Os, and element 108, Hs, was studied on the basis of results of the fully relativistic (four component) and nonrelativistic density functional theory calculations. Relativistic effects were shown to increase bond strengths and decrease bond lengths in these molecules. They are responsible for a decrease in molecular polarizabilities and an increase in ionization potentials. The effects are much stronger in HsO4 than in the lighter congeners. Relativistic effects were also shown to slightly decrease dispersion interaction energies of RuO4, OsO4, and HsO4 with an inert (quartz or silicon nitride) surface, i.e., they increase volatility of these compounds as studied in the "one-atom-at-a-time" gas-phase chromatography experiments. They do, however, not influence the trend in group 8: both relativistically and nonrelativistically, volatility should change as RuO4相似文献
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We investigate for very general cases the multiplet and fine structure splitting of muonelectron atoms arising from the coupling of the electron and muon angular momenta, including the effect of the Breit operator plus the electron state-dependent screening. Although many conditions have to be fulfilled simultaneously to observe these effects, it should be possible to measure them in the 6h-5g muonic transition in the Sn region. 相似文献
120.