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21.
Basing on a formerly described model, the fluctuation of the growth velocity is computed for the growth of a crystal with rotating seed and a solidification interface, which has an maximum at r = rc = 0. The distribution of the velocity and the pattern of the resulting striations is discussed. 相似文献
22.
Abstract Novel liquid crystalline 2-phenyl-1,3,4-thiadiazole based oligomers with three and four rigid aromatic units linked by a flexible central unit have been investigated by polarizing microscopy. The synthesis of these compounds and the influence of structural variations on the mesomorphic properties are described. The combination of suitable mesogenic moieties with appropriate central units leads to oligomers which exhibit Sc phases. 相似文献
23.
Teuscher C 《Chaos (Woodbury, N.Y.)》2007,17(2):026106
Future nanoscale electronics built up from an Avogadro number of components need efficient, highly scalable, and robust means of communication in order to be competitive with traditional silicon approaches. In recent years, the networks-on-chip (NoC) paradigm emerged as a promising solution to interconnect challenges in silicon-based electronics. Current NoC architectures are either highly regular or fully customized, both of which represent implausible assumptions for emerging bottom-up self-assembled molecular electronics that are generally assumed to have a high degree of irregularity and imperfection. Here, we pragmatically and experimentally investigate important design tradeoffs and properties of an irregular, abstract, yet physically plausible three-dimensional (3D) small-world interconnect fabric that is inspired by modern network-on-chip paradigms. We vary the framework's key parameters, such as the connectivity, number of switch nodes, and distribution of long- versus short-range connections, and measure the network's relevant communication characteristics. We further explore the robustness against link failures and the ability and efficiency to solve a simple toy problem, the synchronization task. The results confirm that (1) computation in irregular assemblies is a promising and disruptive computing paradigm for self-assembled nanoscale electronics and (2) that 3D small-world interconnect fabrics with a power-law decaying distribution of shortcut lengths are physically plausible and have major advantages over local two-dimensional and 3D regular topologies. 相似文献
24.
H. Neumann M. Mast J. Enderlein R. D. Tomlinson M. V. Yakushev 《Crystal Research and Technology》1996,31(1):75-85
X-ray excited photoelectron spectroscopy is used to analyse the near-surface properties of CuInTe2 single crystals grown by the vertical Bridgman method. It is found that keeping the crystals at room temperature in air for relatively short times is sufficient for the formation of an oxide layer which consists mainly of TeO2. No detectable amounts of copper or indium oxides could be observed. 相似文献
25.
The high-temperature thermal properties of the ternary oxides LiGaO2 and NaGaO2 are studied by simultaneous differential thermal analysis and thermogravimetry between room temperature and about 1700 °C. For the melting temperature of LiGaO2 a value of 1595 ± 10 °C is determined. NaGaO2 undergoes a solid state phase transition at 1280 ± 10 °C and melts at 1395 ± 10 °C. 相似文献
26.
27.
H. Neumann 《Crystal Research and Technology》1993,28(1):73-82
Theoretical relations are derived for the amplitude of the photoacoustic signal of a gas-coupled cell for thick semiconductor samples including the influence of multiple reflections of light within the sample. It is shown that in the range of low absorption coefficients characteristic of impurity absorption spectra the sensitivity of the cell can be enhanced by using a highly reflecting metal as backing material. Numerical estimates for CuInSe2 are given to illustrate this effect. 相似文献
28.
Doz. Dr. sc. C. Ascheron Doz. Dr. sc. H. Neumann Prof. Dr. sc. G. Kühn 《Crystal Research and Technology》1991,26(3):273-281
Implantation induced changes of the microhardness are studied in GaP single crystals which were bombarded with ions in the range of mass numbers M = 1–40. It is observed that point defects and incorporated hydrogen have a stronger hardening effect. The effect of defect complexes is lower, and amorphized layers are softer than crystalline layers. 相似文献
29.
Infrared reflectivity spectra of thermally oxidized CuInSe2 single crystals are measured at room temperature in the wavenumber range from 180 to 4000 cm−1. A Kramers-Kronig analysis of the spectra reveals seven vibrational modes with frequencies which agree with mode frequencies in In2O3. No vibrational modes due to Cu–O and Se–O bonds could be observed. The results obtained are compared with previous studies of oxidized CuInSe2 crystals. 相似文献
30.
H. Neumann 《Crystal Research and Technology》1991,26(8):1001-1010
The lattice vibrations of the AIIBIII2CVI4 semiconductors with defect-chalcopyrite structure are treated in a simplified version of the Keating model considering only interaction with nearest neighbours and assuming that all anions occupy their ideal lattice sites. It is found that in this model the frequencies of the nonpolar and polar modes with highest energy are determined by the properties of the BIII–CVI sublattice alone. The frequencies of all the other optical modes depend not only on the AII–CVI and BIII–CVI interactions but are also influenced by the presence of the ordered array of vacancies. The results obtained are compared with previous model considerations. 相似文献