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31.
Astrid Brandt Wilhelm Schwieger Karl-Heinz Bergk Paul Grabner Martin Porsch 《Crystal Research and Technology》1989,24(1):47-54
The mechanism of the thermal behaviour of Na-magadiite at a temperature range from 293–573 K was developed based on X-ray diffraction, DTA, DTL, Q-TG, and gravimetric measurements. A structure model (BRANDT et al.) previously proposed was additionally used. It is possible to show that there probably is a connection between the typical modifications of basal spacing and significant shiftings of silicate sheets. Different steps of dehydration, decrystallization and structure variations can be ascribed to the several thermal transitions. The results depend on sample treatment such as the existent or not existent solid-water vapour interaction and the establishment of equilibrium. It seems that there is a predominance of the first mentioned influence. 相似文献
32.
K. Fichtner 《Crystal Research and Technology》1983,18(1):77-84
The thr notation is introduced to describe any stacking variant as a mixture of fractions of the three simplest or regular polytypes: 2H (trigonal), 4H (hexagonal), and 6R (rhombohedral). The new notation is compared with existing ones and applied to pairs of homometric structures and to the characterization of stacking faults. 相似文献
33.
Song Xue Richard W. Haid Regina M. Kluge Xing Ding Batyr Garlyyev Johannes Fichtner Sebastian Watzele Shujin Hou Aliaksandr S. Bandarenka 《Angewandte Chemie (International ed. in English)》2020,59(27):10934-10938
Herein, we demonstrate an easy way to improve the hydrogen evolution reaction (HER) activity of Pt electrodes in alkaline media by introducing Ni–Fe clusters. As a result, the overpotential needed to achieve a current density of 10 mA cm?2 in H2‐saturated 0.1 m KOH is reduced for the model single‐crystal electrodes down to about 70 mV. To our knowledge, these modified electrodes outperform any other reported electrocatalysts tested under similar conditions. Moreover, the influence of 1) Ni to Fe ratio, 2) cluster coverage, and 3) the nature of the alkali‐metal cations present in the electrolyte on the HER activity has been investigated. The observed catalytic performance likely originates from both the improved water dissociation at the Ni–Fe clusters and the subsequent optimal hydrogen adsorption and recombination at Pt atoms present at the Ni–Fe/Pt boundary. 相似文献
34.
35.
K. Fichtner 《Crystal Research and Technology》1984,19(9):K94-K96
36.
Abstract By combination of energy and time of flight detection in ERDA or NRA measurement, the particles' masses can be determined, additionally to the depth information. This leads to unique depth profile determination even for complex targets. Combination with th concept of Jacobi transformations results in extremely fast measurements. In this paper, a way is shown how this concept can be realized even for accelerators ofenergies as low as about 1 MeV. 相似文献
37.
Dupont J Fonseca GS Umpierre AP Fichtner PF Teixeira SR 《Journal of the American Chemical Society》2002,124(16):4228-4229
1-n-Butyl-3-methylimidazolium hexafluorophosphate room-temperature ionic liquid is not only suitable as a medium for the preparation and stabilization of iridium nanoparticles but also ideal for the generation of recyclable biphasic catalytic systems for hydrogenation reactions. Thus, Ir(0) nanoparticles with a mean diameter of 2 nm have been prepared by reduction of Ir(I) dissolved in the ionic liquid with H2. This catalytic solution can be reused several times for the biphasic hydrogenation of olefins under mild reaction conditions. 相似文献
38.
Karl-Heinz Jansen 《Mathematische Annalen》1969,183(3):185-200
Ohne Zusammenfassung 相似文献
39.
Joseph Foricher François Montavon Karl-Heinz Pfoertner Peter Schönholzer 《Helvetica chimica acta》1985,68(3):592-599
Synthesis and Reactions of 5-[p-(Dimethylamino)phenyl]-2,2-dimethyl-4-phenyl-3-oxazoline The title compound 8 has been synthesized in a one-pot reaction of 4′-(dimethylamino)benzoin ( 4 ) with 2-propanone and NH3. The preparation of the intermediate 4 from 3 is the first example of an acid-catalyzed transformation of the stable benzoin 3 into the corresponding less stable benzoin 4 . Structures and yields of various by-products occurring under different reaction conditions during the synthesis of 8 from 4 are given. The O-atom of the 3-oxazoline ring in 8 could be replaced by S from P2S5 yielding the 3-thiazoline 14 . Separation of the enantiomers of the racemate 8 could only be performed by transforming them into the trimethylanilinium salts 8b and 8c of (−)- and (+)-10-camphorsulfonic acid, respectively. Solid NaOAc in boiling toluene caused the precipitation of the 10-camphorsulfonic acids from the quaternary ammonium salts as sodium salts and the removing of the third methyl group from the quaternary ammonium salts as AcOMe to give the enantiomers (−)-(5S)- 8 and (+)-(5R)- 8 . Their absolute configurations are deduced from an X-ray analysis of 8b . 相似文献
40.