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101.
Surface analytical investigation of the tritium getter ZrCO after exposure to various gases 总被引:1,自引:0,他引:1
Heike Glasbrenner Hanns Klewe-Nebenius Michael Bruns Gerda Pfennig Ralf-Dieter Penzhorn Hans Joachim Ache 《Mikrochimica acta》1992,107(3-6):207-217
ZrCo is a hydride forming material frequently investigated and proposed for storage and handling of hydrogen isotopes. It is of special interest for deuterium and tritium storage needed for the operation of a nuclear fusion reactor. An interaction of ZrCo powder with contaminant gases particularly during the thermal release of the hydrogen isotopes from the hydride at temperatures above 300 °C was found to cause a reduction of the reactivity of the powder. Consequently, a serious decrease of the hydrogen storage capacity occurs. From surface analytical investigations of ZrCo after exposure to the contaminant gases CO, CO2, O2, N2, CH4, and C2H4 it was concluded that CH4, C2H4, O2, or N2 react predominantly with Zr, the principal hydride forming alloy component, to carbide, nitride, and/or oxide. The resulting decrease of the storage capacity is possibly due to either a reduction in the amount of unreacted Zr available for the formation of Zr hydrides or to a formation of a thick protective overlayer. CO or CO2, which react mainly with the Co component but with Zr in surface near layers only, cause a less pronounced decrease in storage capacity. 相似文献
102.
E. Cesari J. Ortín J. Vińals J. Hatt W. Zielenkiewicz V. Torra 《Thermochimica Acta》1983,71(3):351-357
Quantitative criteria to ascertain the quality of calorimetric models based on physical parameters are presented. These include not only a comparison between model and experimental pulse responses, especially for the larger time constants, but also an analysis of their spectra up to the frequential limit brought about by the experimental noise.A calorimetric model based on the physical parameters of a Unipan 600 calorimeter is used to reconstruct a given power dissipation. The results are then compared to those given by other methods, i.e. dynamic optimization, inverse filtering and harmonic analysis. 相似文献
103.
Hauke Reddmann Prof. Dr. Marc Heinrich Prosenc Prof. Dr. Hanns‐Dieter Amberger 《无机化学与普通化学杂志》2012,638(5):791-797
The far and mid infrared (FIR/MIR) spectra of powdered Os(η5‐C5Me5)2 (OsCp*2) as well as the polarized Raman spectra of an oriented single crystal (where the two molecules of D5h symmetry in the unit cell are uniformly oriented) have been recorded. The latter allow the assignment of the observed Raman lines to irreducible representations (irreps) which agree well with the predictions of a calculation applying density functional theory. This finding suggests additional correlation of the observed (unpolarized) bands in the FIR/MIR spectra with the calculated wavenumbers (and their irreps) of IR active normal modes. Neglecting νCH vibrations an r.m.s. deviation of 15.8 cm–1 for 40 assignments (Raman and IR) could be achieved. Skeletal and intra‐ligand vibrations could be identified and a number of previous assignments of the latter had to be revised. Because of mixing with skeletal modes some of the low frequency intra‐ligand vibrations display a noticeable dependence on the mass of the central atom which prevents the direct transfer of the identified γCCH3 and βCCH3 normal modes from MCp*2 (M = Fe, Ru, Os) to LnCp*3 (Ln = La, Ce, Pr, Nd, Sm) complexes. 相似文献
104.
105.
A. J. Hatt N. A. Spaldin 《The European Physical Journal B - Condensed Matter and Complex Systems》2009,71(3):435-437
BiMnO3 has long been at the forefront of multiferroics research. Controversy exists, however, over whether it is actually ferroelectric
and thus multiferroic, or whether the stereochemically active lone pairs order in an anti-polar centrosymmetric arrangement.
Here we investigate the effect of epitaxial strain on the electronic ordering and symmetry of BiMnO3 to determine whether strain effects might explain the apparently contradictory experimental results regarding ferroelectricity.
Using ab-initio methods, we calculate the polarization of BiMnO3 under bi-axial strain in the pseudo-cubic (001) plane, examining both tensile and compressive values of strain. We find no
significant polarization or re-ordering of Bi lone-pairs under experimentally achievable strain values, and conclude that
BiMnO3 remains centrosymmetric and non-polar. 相似文献
106.
Maxim Bykov Stella Chariton Elena Bykova Saiana Khandarkhaeva Timofey Fedotenko Alena V. Ponomareva Johan Tidholm Ferenc Tasndi Igor A. Abrikosov Pavel Sedmak Vitali Prakapenka Michael Hanfland Hanns‐Peter Liermann Mohammad Mahmood Alexander F. Goncharov Natalia Dubrovinskaia Leonid Dubrovinsky 《Angewandte Chemie (International ed. in English)》2020,59(26):10321-10326
Polynitrides are intrinsically thermodynamically unstable at ambient conditions and require peculiar synthetic approaches. Now, a one‐step synthesis of metal–inorganic frameworks Hf4N20?N2, WN8?N2, and Os5N28?3 N2 via direct reactions between elements in a diamond anvil cell at pressures exceeding 100 GPa is reported. The porous frameworks (Hf4N20, WN8, and Os5N28) are built from transition‐metal atoms linked either by polymeric polydiazenediyl (polyacetylene‐like) nitrogen chains or through dinitrogen units. Triply bound dinitrogen molecules occupy channels of these frameworks. Owing to conjugated polydiazenediyl chains, these compounds exhibit metallic properties. The high‐pressure reaction between Hf and N2 also leads to a non‐centrosymmetric polynitride Hf2N11 that features double‐helix catena‐poly[tetraz‐1‐ene‐1,4‐diyl] nitrogen chains [?N?N?N=N?]∞. 相似文献
107.
Christoph Helling George E. Cutsail Hanns Weinert Christoph Wlper Stephan Schulz 《Angewandte Chemie (International ed. in English)》2020,59(19):7561-7568
We report on the structures of three unprecedented heteroleptic Sb‐centered radicals [L(Cl)Ga](R)Sb. ( 2‐R , R=B[N(Dip)CH]2 2‐B , 2,6‐Mes2C6H3 2‐C , N(SiMe3)Dip 2‐N ) stabilized by one electropositive metal fragment [L(Cl)Ga] (L=HC[C(Me)N(Dip)]2, Dip=2,6‐i‐Pr2C6H3) and one bulky B‐ ( 2‐B ), C‐ ( 2‐C ), or N‐based ( 2‐N ) substituent. Compounds 2‐R are predominantly metal‐centered radicals. Their electronic properties are largely influenced by the electronic nature of the ligands R, and significant delocalization of unpaired‐spin density onto the ligands was observed in 2‐B and 2‐N . Cyclic voltammetry (CV) studies showed that 2‐B undergoes a quasi‐reversible one‐electron reduction, which was confirmed by the synthesis of [K([2.2.2]crypt)][L(Cl)GaSbB[N(Dip)CH]2] ([K([2.2.2]crypt)][ 2‐B ]) containing the stibanyl anion [ 2‐B ]?, which was shown to possess significant Sb?B multiple‐bonding character. 相似文献
108.
Stefanie Schwamborn Leonard Stoica Dr. Sebastian Neugebauer Dr. Torsten Reda Dr. Hanns‐Ludwig Schmidt Prof. Dr. Wolfgang Schuhmann Prof. Dr. 《Chemphyschem》2009,10(7):1066-1070
Local redox conversion of nitro end groups of a 4‐nitrothiophenol self‐assembled monolayer on gold is achieved by direct‐mode scanning electrochemical microscopy (SECM). Potential pulses are applied to the modified gold surface leading to local reduction of nitro end groups to either hydroxylamine (?0.47 V, see picture) or amino groups (?0.6 V) exclusively beneath the positioned SECM tip.
109.
Janusz Lipkowski Anna Zielenkiewicz Jacek Hatt Wojciech Zielenkiewicz 《Journal of inclusion phenomena and macrocyclic chemistry》1989,7(5):511-518
The selectivity of inclusion ofp-xylene andp-dibromobenzene from their liquid mixtures by the host [Ni(NCS)2(4-methylpyridine)4] and the enthalpy of clathration were determined.p-Dibromobenzene is clathrated significantly more thanp-xylene. The heats of clathration show a linear dependence upon the composition of the enclathrated mixture and are considered to be indicative of the conclusion that the guest-guest interactions are negligible from the thermochëmical point of view. By comparing data presented herein with some literature data on competitive clathration an attempt to derive the entropy of guest exchange in the clathrate was performed.Presented at the International Seminar on Inclusion Compounds, Jaszowiec, Poland, 24–26 September, 1987. 相似文献
110.
Tummas Napoleon Arge Zuzana Konpkov Drthe Haase Hanns‐Peter Liermann Ullrich Scherf Suchismita Guha Matti Knaapila 《Journal of Polymer Science.Polymer Physics》2019,57(7):392-396
We report on X‐ray scattering measurements of helical poly[9,9‐bis(2‐ethylhexyl)‐fluorene‐2,7‐diyl] by mapping the sample with 10 μm spatial resolution from 0.3 GPa to 36 GPa. We follow the strongest 00l reflection, which moves toward higher scattering angles with pressure indicating planarization of helical polyfluorene. Lateral inhomogeneity is increased for >10 GPa concomitant with the solidification of the pressure transmitting medium (a 4:1 mixture of methanol and ethanol). We also follow the 00l reflection with increasing temperature at the constant pressure of 4.3 GPa in neon. We observe a sharp shift toward higher scattering angles indicative of a phase transition at 167–176 °C. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 392–396 相似文献