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141.
Heribert A. Graetsch 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(11):i152-i153
The title compound, SrZnCoFe16O27 (ZnCo‐W), strontium zinc cobalt hexadecairon oxide, crystallizes in space group P63/mmc, with the Sr atom at a site with symmetry and Zn2+ located at two tetrahedral sites (4e and 4f, each with 3m symmetry) of the spinel blocks. The Zn occupancy is 36% on equipoint 4e and 14% on 4f. The enrichment of diamagnetic ions on one of seven sublattices is thought to be responsible for the high temperature dependence of the saturation magnetization. 相似文献
142.
The growth history of Hg1−xCdxTe films deposited on (100) CdTe substrates by chemical vapor transport (CVT) has been studied, for the first time, by using
a transient growth technique. The observed morphological evolution of Hg1−xCdxTe films deposited at 545°C shows a transition behavior from three-dimensional (3D) islands to two-dimensional (2D) layer
growth. The experimental results indicate that the so-called critical time needed for the above morphological transition is
about lh under present experimental conditions. Based on the chemical bonding properties of Hg1−xCdxTe, and on the behavior of the morphological transition, the Stranski-Krastanov growth mode is suggested for the epitaxial
growth system. The time dependence of the growth thickness, of the growth rate (R100) along the [100] direction, and of the surface composition all reveal a transient behavior. These are related to the nature
of the Hg1-xCdxTe/ (100)CdTe heterojunction and to the surface reactions. Comparison of the growth rates and of the total mass deposited
as a function of time shows the relationship between epitaxial growth and mass flux of the Hg1−xCdxTe-HgI2 chemical vapor transport system. 相似文献
143.
As part of a systematic investigation of the effects of substrate surfaces on epitaxial growth, the transient behavior of
Hg1−xCdxTe film growth on (111)B CdTe by chemical vapor transport (CVT) has been studied as a function of growth time under vertical
stabilizing (hot end on top) and vertical destabilizing (hot end at bottom) ampoule orientations. The experim ental results
show the morphological transition of the Hg1−xCdxTe deposition on (111)B CdTe at 545°C from three-dimensional islands to layers within about 0.5 and 0.75 h for the growth
under vertical stabilizing and destabilizing conditions, respectively. The combined effects of small convective flow disturbances
on the growth morphology and defect formation are measurable. The overall trends of the time dependent growth rates and compositions
of the Hg1−xCdxTe epitaxial layers under stabilizing and destabilizing conditions are similar. The system atically higher growth rates of
the Hg1−xCdxTe films by about 10% under vertical destabilizing conditions could be influenced by a small convective contribution to the
mass transport. The combined results show that improved Hg1−xCdxTe epitaxial layers of low twin density on (111)B CdTe substrates can be obtained by CVT under vertical stabilizing conditions. 相似文献
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148.
Burkhard Horstkotte Stefan Wiedemeier Víctor Cerdà Reiner Luttmann 《Analytica chimica acta》2006,559(2):248-256
A sequential injection analysis (SIA) method for the at-line determination of formaldehyde in a cultivation process of Pichia pastoris is presented. A genetically modified yeast strain was used for cultivation processes wherein methanol feed induced the production of the recombinant protein 1-3del I-TAC. Recurring measurements of culture medium, its blank and including standard addition were performed with Nash reagent using an automated syringe device and photometric detection. The apparatus was coupled via a laboratory-made flow-through adapter to a continuous filtered and cell-medium flow from the bioreactor. At-line monitoring of formaldehyde was performed at two cultivations, each of 250 h during fed-batch phases with glycerol and methanol as carbon sources. High reliability, robustness and reproducibility of the method, the software and the instrumentation as well as the high selectivity of the reaction were demonstrated. 相似文献
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150.
Heribert Wiedemeier 《Journal of solid state chemistry》2010,183(10):2317-2323
Correlations of computed Schottky constants () with structural and thermodynamic properties showed linear dependences of log KS on the lattice energies for the Zn-, Cd-, Hg-, Mg-, and Sr-chalcogenides and for the Na- and K-halides. These findings suggest a basic relation between the Schottky constants and the lattice energies for these families of compounds from different parts of the Periodic Table, namely, =−(2.303nRT log KS)+2.303nRmb+2.303nRTib. is the experimental (Born-Haber) lattice energy (enthalpy), n is a constant approximately equal to the formal valence (charge) of the material, mb and ib are the slope and intercept, respectively, of the intercept b (of the log KS versus linear relation) versus the reciprocal temperature. The results of this work also provide an empirical correlation between the Gibbs free energy of vacancy formation and the lattice energy. 相似文献