BCsGaH0 9 P 2 , monoclinic, P12i/cl (No. 14), a = 9.259(1) Á, è = 8.6462(9) Â, c = 9.615(1) k,ß= 103.059(6)°,V= 749.8 Â 3 Z==4 > R g i(F) = 0.050, wR rei (F 2 ) = 0.104, T= 295 K.
The curvature of space-time and its consequences are often far removed from experimental accessibility. A particularly elusive effect is the generation of a heat current by the mixed axial-gravitational anomaly. However, recent theoretical investigations suggest that the magneto-thermal conductivity of condensed matter Weyl systems is linked to such an anomaly-related heat current even in flat space-time. In this paper, we report a positive magneto-thermal conductivity in the semimetal GdPtBi for collinear temperature gradients and magnetic fields ($\nabla T\parallel\mathbf{B}$). The positive magneto-thermal conductivity emerges concurrently with the established anomaly-related magneto-electrical conductivity of Weyl fermions, and is locked to the parallel alignment of $\nabla T$ and $\mathbf{B}$. This observation is consistent with the generation of an anomalous heat current, a fingerprint of the existence of the mixed axial-gravitational anomaly.
The reaction of W6Br12 with AgBr in evacuated silica tubes (temperature gradient 925 K/915 K) yielded brownish black octahedra of Ag[W6Br14] (I) and yellowish green platelets of Ag2[W6Br14] (II) both in the low temperature zone. (I) crystallizes cubically (Pn3 (no. 201); a = 13.355 Å, Z = 4) and (II) monoclinically (P21/c (no. 14); a = 9.384 Å, b = 15.383 Å, c = 9.522 Å, β = 117.34°, Z = 2). Both crystal structures contain isolated cluster anions, namely [(W6Bri8)Bra6]1– and [(W6Bri8)Bra6])]2–, respectively, with the mean distances and angles: (I) d(W–W) = 2.648 Å, d(W–Bri) = 2.617 Å, d(W–Bra) = 2.575 Å, d(Bri…Bri) = 3.700 Å, d(Bri…Bra) = 3.692 Å, ∠W–Bri–W = 60.78°. (II) d(W–W) = 2.633 Å, d(W–Bri) = 2.624 Å, d(W–Bra) = 2.613 Å, d(Bri…Bri) = 3.710 Å, d(Bri…Bra) = 3.707 Å, ∠W–Bri–W = 60.23°. The Ag+ cations are trigonal antiprismatically coordinated in (I) with d(Ag–Br) = 2.855 Å, but distorted trigonally planar in (II) with d(Ag–Br) = 2.588–2.672 Å. The structural details of hitherto known compounds with [W6Br14] anions will be discussed. Die Clusterverbindungen Ag[W6Br14] und Ag2[W6Br14] Bei der Umsetzung von W6Br12 mit AgBr in evakuierten Quarzglasampullen (Temperaturgradient 925 K/915 K) entstehen in der kalten Zone nebeneinander schwarzbraune Oktaeder von Ag[W6Br14] (I) und gelbgrüne Blättchen von Ag2[W6Br14] (II). (I) kristallisiert kubisch (Pn3 (Nr. 201); a = 13.355 Å, Z = 4) und (II) monoklin (P21/c (Nr. 14); a = 9.384 Å, b = 15.383 Å, c = 9.522 Å, β = 117.34°, Z = 2). Die Kristallstrukturen enthalten die isolierten Clusteranionen [(W6Bri8)Bra6]1– bzw. [(W6Bri8)Bra6])]2–, mit den mittleren Abständen und Winkeln: (I) d(W–W) = 2.648 Å, d(W–Bri) = 2.617 Å, d(W–Bra) = 2.575 Å, d(Bri…Bri) = 3.700 Å, d(Bri…Bra) = 3.692 Å, ∠W–Bri–W = 60.78°. (II) d(W–W) = 2.633 Å, d(W–Bri) = 2.624 Å, d(W–Bra) = 2.613 Å, d(Bri…Bri) = 3.710 Å, d(Bri…Bra) = 3.707 Å, ∠W–Bri–W = 60.23°. Die Ag+-Kationen sind in (I) trigonal-antiprismatisch koordiniert mit d(Ag–Br) = 2.855 Å, in (II) verzerrt trigonal-planar mit d(Ag–Br) = 2.588–2.672 Å. Die strukturellen Einzelheiten der bisher bekannten Verbindungen mit [W6Br14]-Anionen werden diskutiert.
Ag2.10Ce2P3.8O, tetragonal, Wmmm (No. 139), a = 4.0037(2) Â, c = 20.435(1)Â, V= 327.6 Â 3 , Z= 2, RgdF) = 0.049, wRobs(F) = 0.049, Τ = 293 Κ. Source of materialInitial components in atomic ratio 1:1:2 were mixed, pressed into pellets and sealed together with 0.15 g of iodine into evacuated silica ampoule with the length of 25 cm.Total mass of the sample was about 1 g.A two-zone heating with the temperatures of 1070 Κ and 870 Κ on the "hot" and "cold" end of the ampoule, respectively, was used for the synthesis.The sample was kept at
Nanoparticle assemblies with long-range packing order and preferred crystallographic orientation of building blocks, i.e., mesocrystals, are of high interest not only because of their unique physical properties but also due to their complex structure and morphogenesis. In this study, faceted mesocrystals have been assembled from the dispersion of truncated cubic-shaped iron oxide nanoparticles stabilized by oleic acid (OA) molecules using the nonsolvent "gas phase diffusion technique" into an organic solvent. The effects of synthesis conditions as well as of the nanoparticle size and shape on the structure and morphogenesis of mesocrystals were examined. The interactions of OA-capped iron oxide nanoparticles with solvent molecules were probed by analytical ultracentrifugation and double difference pair distribution function analysis. It was shown that the structure of the organic shell significantly depends on the nature and polarity of solvent molecules. For the nonpolar solvents, the interaction of the aliphatic chains of OA molecules with the solvent molecules is favorable and the chains extend into the solvent. The solvation shell around the nanoparticles is more extended in nonpolar and more compact in polar solvents. There is a clear trend for more spherical particles to be assembled into the fcc superlattice, whereas less truncated cubes form rhombohedral and tetragonal structures. The observed changes in packing symmetry are reminiscent of structural polymorphism known for "classical" (atomic and molecular) crystals.
[Co 2 (CO) 6 (μ-S 2 )] 2+ (AsF 6 -) 2 · 1/2SO 2 is formed in the reaction of S 8 2+ (AsF 6 -) 2 with Co 2 (CO) 8 in SO 2 at R.T.. The complex crystallizes in the orthorhombic space group Pbcn (No. 60) with a = 1508.0(9), b = 1642.7(8), c = 871.3(6) pm, V = 2158(2)•10 6 pm 3 , Z = 4. In the tetrahedral Co 2 S 2 unit a short S–S distance (198 pm) is observed.
A comparative study of the filled skutterudite compounds $\mathrm{Yb}{\mathrm{Fe}}_{4}{\mathrm{Sb}}_{12}$ and $\mathrm{Ca}{\mathrm{Fe}}_{4}{\mathrm{Sb}}_{12}$ is presented. Crystal structure investigations and measurements of magnetic susceptibility, specific heat and electrical resistivity in magnetic field, and x-ray absorption spectroscopy have been performed. Almost identical structural, magnetic, and electronic properties of both compounds are observed. Electronic structure calculations support this similarity. It is concluded that ytterbium in ${\mathrm{Yb}}_{1\ensuremath{-}x}{\mathrm{Fe}}_{4}{\mathrm{Sb}}_{12}$ is stable divalent and the magnetic moments in both materials are solely due to itinerant-electron paramagnetism of the $\mathrm{Fe}\ensuremath{-}\mathrm{Sb}$ polyanion. The calcium and ytterbium iron-antimony skutterudites are nearly ferromagnetic metals and their properties are mainly governed by spin fluctuations.
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An unusual and chiral molecular framework characterizes the crystal structure of the air-sensitive title coumpound 1, which solidifies at 273 K. The molecular fragments on either side of the stretched CC bond (138 pm) are twisted by 28° relative to each other (picture bottom right). Even in the gas phase 1 shows an unusual molecular structure, dictated by steric congestion. The four nitrogen electron pairs of the substantially flattened dimethylamino substituents are bent out of the optima1 orientation for π interaction (the torsion angle ω(CC-NC2) is 55o.
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