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1.
Vasyl' I. Zaremba Dariusz Kaczorowski Galyna P. Nychyporuk Ute Ch. Rodewald Birgit Heying Rainer Pttgen 《无机化学与普通化学杂志》2006,632(6):975-980
New indides Ce3Ge0.66In4.34 and Ce11Ge4.74In5.26 were synthesized from the elements by arc‐melting and subsequent annealing at 870 K. Single crystals were grown through special annealing procedures in sealed tantalum tubes in a high‐frequency furnace. Both compounds were investigated on the basis of X‐ray powder and single crystal data: I4/mcm, La3GeIn4 type, a = 848.8(1), c = 1192.0(2) pm, Z = 4, wR2 = 0.0453, 499 F2 values, 17 variables for Ce3Ge0.66In4.34 and I4/mmm, Sm11Ge4In6 type (ordered version of the Ho11Ge10 type), a = 1199.3(2), c = 1662.0(3) pm, wR2 = 0.0507, 1217 F2 values, 41 variables for Ce11Ge4.74In5.26. The Ce3Ge0.66In4.34 structure shows a mixed Ge/In occupancy on the 4c Wyckoff position. This site is octahedrally coordinated by cerium atoms. These octahedra share all edges, leading to a three‐dimensional network. The latter is penetrated by a two‐dimensional indium substructure which consists of flattened tetrahedra at In–In distances of 291 and 300 pm. The Ce11Ge4.74In5.26 structure contains three crystallographically independent germanium sites. The latter are coordinated by eight or nine cerium neighbors. These CN8 and CN9 polyhedra are condensed to a complex network which is penetrated by a three‐dimensional indium network with In–In distances of 301–314 pm. The 16m site shows a mixed In/Ge occupancy. Chemical bonding in both compounds is dominated by the p elements. Both ternaries studied exhibit localized magnetism due to the presence of Ce3+ ions. The compound Ce3GeIn4 remains paramagnetic down to 1.72 K, whereas Ce11Ge4In6 orders ferromagnetically at TC = 7.5 K. 相似文献
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3.
Synthesis of potassium bismuth titanate ferroelectric by heating of mixtures prepared using oxide precursors, i.e. Bi2O3, TiO2 and K2CO3 was investigated. DTA, TG, XRD and SEM methods were used to study the formation of intermediate compounds and the final product.
Usage of associated homogenization and grinding of precursors mixture permits to decrease the temperature of formation of
K0.5Bi0.5TiO3.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
4.
Ihor R. Muts Falko M. Schappacher Vasyl’ I. Zaremba 《Journal of solid state chemistry》2007,180(8):2202-2208
New indides SrAu3In3 and EuAu3In3 were synthesized by induction melting of the elements in sealed tantalum tubes. Both indides were characterized by X-ray diffraction on powders and single crystals. They crystallize with a new orthorhombic structure type: Pmmn, Z=2, a=455.26(9), b=775.9(2), c=904.9(2) pm, wR2=0.0425, 485 F2 values for SrAu3In3 and a=454.2(2), b=768.1(6), c=907.3(6) pm, wR2=0.0495, 551 F2 values for EuAu3In3 with 26 variables for each refinement. The gold and indium atoms build up three-dimensional [Au3In3] polyanionic networks, which leave distorted hexagonal channels for the strontium and europium atoms. Within the networks one observes Au2 atoms without Au-Au contacts and gold zig-zag chains (279 pm Au1-Au1 in EuAu3In3). The Au-In and In-In distances in EuAu3In3 range from 270 to 290 and from 305 to 355 pm. The europium atoms within the distorted hexagonal channels have coordination number 14 (8 Au+6 In). EuAu3In3 shows Curie-Weiss behavior above 50 K with an experimental magnetic moment of 8.1(1) μB/Eu atom. 151Eu Mössbauer spectra show a single signal at δ=−11.31(1) mm/s, compatible with divalent europium. No magnetic ordering was detected down to 3 K. 相似文献
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6.
Irina O. Zhuravel Oleg V. Zaremba Oleksandr S. Detistov Svitlana S. Kovalenko Valentin P. Chernykh 《合成通讯》2013,43(21):3778-3784
New 5-hydroxymethyl-8-methyl-3-(3-aryl-[1,2,4]oxadiazol-5-yl)-2H-pyrano-[2,3-c]pyridin-2-ones and their esters were synthesized. The structure of obtained compounds was determined through a complete 1H NMR analysis. 相似文献
7.
Finite-temperature simulations are used to study quadrupole excitations of a trapped Bose-Einstein condensate. We focus specifically on the m = 0 mode, where a long-standing theoretical problem is to account for an anomalous variation of the mode frequency with temperature. We explain this behavior in terms of the excitation of two separate modes, corresponding to the coupled motion of the condensate and the thermal cloud. The relative amplitude of the modes depends sensitively on the temperature and on the frequency of the harmonic drive used to excite them. Good agreement with experiment is found for appropriate drive frequencies. 相似文献
8.
The feasibility of studying the energetics of light impurities in metallic hosts by treating the impurity ion plus its screening cloud as a unit, or “quasi-atom”, is explored. In the simplest approximation the energy of the impurity is given in terms of the local host electron density. This approach is tested against results taken from the literature for the energy of light atoms in inhomogeneous electronic environments. Corrections to the simplest approximation are discussed. 相似文献
9.
E. Zaremba 《Surface science》1985,151(1):91-102
A continuum dielectric theory is used to investigate the Van der Waals interaction between an atom and a point defect on a planar surface. A vacancy (or adsorbed atom) is modelled by a hemispherical pit (or bump) which perturbs the dielectric response of the defect-free surface. The anisotropy of the interaction is found to be qualitatively different for the vacancy and adsorbate situations. The estimated magnitude of the interaction seems consistent with recent experimental results. 相似文献
10.
Motivated by the far-infrared transmission experiments of Demel et al., we have investigated the magnetoplasmon excitations in an array of quantum dots within the Thomas–Fermi–Dirac–von Weizsäcker (TFDW) approximation. Detailed calculations of the magnetic dispersion and power absorption from a uniform radiation field unambiguously demonstrates that the noncircular symmetry of the individual dots is responsible for the anticrossing behaviour observed in the experiments. The interdot Coulomb interaction is unimportant at the interdot separation of the samples studied. 相似文献