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Komornikov V. A. Grebenev V. V. Timakov I. S. Ksenofontov D. A. Andreev P. V. Makarova I. P. Selezneva E. V. 《Crystallography Reports》2019,64(3):479-483
Crystallography Reports - The phase equilibria in the K3H(SO4)2–Rb3H(SO4)2–H2O cross section have been investigated under isothermal conditions at 25°C. The concentration limits of... 相似文献
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Gieck C Derstroff V Block T Felser C Regelsky G Jepsen O Ksenofontov V Gütlich P Eckert H Tremel W 《Chemistry (Weinheim an der Bergstrasse, Germany)》2004,10(2):382-391
The new quaternary niobium thiophosphates ANb(2)P(2)S(12) (A=K, Rb, Cs) have been prepared and characterized. The title compounds were synthesized by reacting Nb metal, A(2)S, P(2)S(5), and S at 600-700 degrees C in evacuated silica tubes. They crystallize as "stuffed" variants of the tetragonal TaPS(6) structure type in the tetragonal space group I$\bar 4$2d with eight formula units per unit cell and lattice constants a=15.923(2) and c=13.238(3) A for CsNb(2)P(2)S(12), a=15.887(3) and c=13.132(3) A for RbNb(2)P(2)S(12), and a=15.850(2) and c=13.119(3) A for KNb(2)P(2)S(12). Their structures are based on double helices formed from interpenetrating, noninteracting spiral chains of binuclear [Nb(2)S(12)] cluster units and [PS(4)] thiophosphate groups. The cavities and tunnels, which are formed by the helical chains, are filled with A(+) ions. Temperature-dependent conductivity studies reveal thermally activated electrical transport behavior. This result is consistent with the observation of a temperature-dependent contribution to the (31)P MAS-NMR shift, suggesting that the delocalized s-electron spin density increases with increasing temperature. These findings are supported by the results of tight-binding band structure calculations which reveal that the unusual electrical transport behavior of ANb(2)P(2)S(12) is a consequence of the structure symmetry. Therefore, CsNb(2)P(2)S(12) may be considered a chalcogenide analogue of metal phosphate bronzes. 相似文献
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Results of TDDFT calculations of characteristics for excited singlet states of mono- and diisocyanates and carbamates containing from one to three phenyl groups are presented. The influence of the structural composition of the isocyanate/carbamate on the formation of its UV absorption spectrum was analyzed. 相似文献
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M.?B.?ShundalauEmail author P.?S.?Chybirai A.?I.?Komyak A.?P.?Zazhogin M.?A.?Ksenofontov D.?S.?Umreiko 《Journal of Applied Spectroscopy》2011,78(3):326-336
We present results of ab initio and DFT calculations of the structure and IR vibrational spectra of the monomer and dimers of N,N-dimethylformamide (DMF).
The calculations were carried out in the B3LYP/cc-pVDZ approximation with subsequent force-field scaling. The calculated characteristics
of the vibrational spectra of DMF show satisfactory agreement with experimental values, allowing them to be used in spectral
and structural analysis. 相似文献