10,698 research outputs found
Synthesis and characterization of multiferroic BiMnO
We report on the high pressure synthesis of BiMnO, a manganite
displaying a "quadruple perovskite" structure. Structural characterization of
single crystal samples shows a distorted and asymmetrical coordination around
the Bi atom, due to presence of the lone pair, resulting in
non-centrosymmetric space group Im, leading to a permanent electrical dipole
moment and ferroelectric properties. On the other hand, magnetic
characterization reveals antiferromagnetic transitions, in agreement with the
isostructural compounds, thus evidencing two intrinsic properties that make
BiMnO a promising multiferroic material.Comment: 4 pages, 3 figure
Crystallographic disorder and electron scattering on structural two-level systems in ZrAs1.4Se0.5
Single crystals of ZrAs1.4Se0.5 (PbFCl type structure) were grown by chemical
vapour transport. While their thermodynamic and transport properties are
typical for ordinary metals, the electrical resistivity exhibits a shallow
minimum at low temperatures. Application of strong magnetic fields does not
influence this anomaly. The minimum of the resistivity in ZrAs1.4Se0.5
apparently originates from interaction between the conduction electrons and
structural two-level systems. Significant disorder in the As-Se substructure is
inferred from X-ray diffraction and electron microprobe studies
1-(4-Bromo-3-chlorophenyl)-3-methoxy-3-methylurea (chlorbromuron)
In the title urea-based herbicide, C9H10BrClN2O2, there exist multiple inter- and intramolecular interactions. Most notably, the intramolecular hydrogen bond between the urea carbonyl O atom and an aromatic H atom affects the planarity and torsion angles of the molecule by restricting rotations about the Ar—secondary amine N and the secondary amine N and the carbonyl C. The two N atoms in the urea fragment are in different environments. One is planar; the other, pseudo-C
3v. It is likely that the different nitrogen-atom geometries and the restricted rotations within the molecule impact the bioactivity of chlorbromuron
Non-Fermi liquid behavior in a fluctuating valence system, the filled skutterudite compound CeRu_{4}As_{12}
Electrical resistivity , specific heat C, and magnetic susceptibility
measurements made on the filled skutterudite CeRu_4As_{12} reveal
non-Fermi liquid (NFL) T - dependences at low T, i.e., (T) T^{1.4}
and weak power law or logarithmic divergences in C(T)/T and (T).
Measurements also show that the T - dependence of the thermoelectric power S(T)
deviates from that seen in other Ce systems. The NFL behavior appears to be
associated with fluctuations of the Ce valence between 3^+ and 4^+ rather than
a typical Kondo lattice scenario that would be appropriate for an integral Ce
valence of 3^+.Comment: 18 pages, 5 figure
Synthesis and crystal structure of N-6-[(4-pyridylamino) carbonyl]-pyridine-2-carboxylic acid methyl ester zinc complex
A reaction between monoamide ligand namely N-6-[(4-pyridylamino)carbonyl]-pyridine-2-carboxylic acid methyl ester (L4) and zinc chloride has been attempted in order to generate a carboxylate complex suitable for anion inclusion. This reaction gives rise to a formation of discrete complex with general formula [ZnCl2(L4)2]. Complex [ZnCl2(L4)2] crystallizes in the monoclinic space group, P21/c, with one zinc(II) center, one molecule of ligand L4, one coordinated chloride and one methanol molecule in the asymmetric unit. The extended structure of this molecule shows that the zinc atom is coordinated by four donors: two L4 and two chloride anions. The zinc atom adopts distorted tetrahedral geometry with the angles between the donors in the range 103.62(11)-122.74(8)°. In this study, the amide cavity is bound with methanol through hydrogen-bonding interactions. The methanol molecules is hydrogen bonded to the amide moiety with bond lengths O30-H8···O12 and N17-H17···O30 of 1.988 and 2.078 Å, respectively
NaV2O4: a Quasi-1D Metallic Antiferromagnet with Half-Metallic Chains
NaV2O4 crystals were grown under high pressure using a NaCl flux, and the
crystals were characterized with X-ray diffraction, electrical resistivity,
heat capacity, and magnetization. The structure of NaV2O4 consists of double
chains of edge-sharing VO6 octahedra. The resistivity is highly anisotropic,
with the resistivity perpendicular to the chains more than 20 times greater
than that parallel to the chains. Magnetically, the intrachain interactions are
ferromagnetic and the interchain interactions are antiferromagnetic; 3D
antiferromagnetic order is established at 140 K. First principles electronic
structure calculations indicate that the chains are half metallic.
Interestingly, the case of NaV2O4 seems to be a quasi-1D analogue of what was
found for half-metallic materials.Comment: 14 pages, including 4 figures and 1 table, accepted for publication
in PR
cis-Bis[4-amino-N-(pyrimidin-2-yl)benzenesulfonamido-κ2 N,N′]bis(dimethyl sulfoxide-κO)cadmium
The complete molecule of the title compound, [Cd(C10H9N4O2S)2(C2H6OS)2], is completed by the application of a twofold rotation axis. The CdII atom is six coordinated by two bidentate sulfadiazinate anions and two dimethylsulfoxide molecules. The resulting N4O2 donor set displays a distorted trigonal–prismatic coordination geometry. The S atom and methyl groups of dimethylsulfoxide are disordered over two sets of sites, with site occupancies of 0.715 (4) and 0.285 (4). The crystal structure features intermolecular N—H⋯N and N—H⋯O hydrogen bonds that lead to the formation of layers in the ab plane
Bis[4-amino-N-(pyrimidin-2-yl)benzenesulfonamidato]-κ2 N,N′;κN-aquabis(dimethylformamide-κO)cadmium(II) monohydrate
In the title compound, [Cd(C10H9N4O2S)2(C3H7NO)2(H2O)]·H2O, the CdII ion displays a grossly distorted octahedral (or irregular) mer-CdN3O3 coodination polyhdron arising from its coordination by one N,N′-bidentate sulfadiazinate anion, one monodentate sulfadiazinate anion, two O-bonded dimethylformamide molecules and one water molecule. A short Cd⋯N contact [2.890 (3) Å] to the monodentate sulfadiazinate ion also occurs. The dihedral angles between the planes of the aromatic rings of the anions are 86.81 (14) and 68.65 (14)°. The crystal structure features intermolecular N—H⋯O, O—H⋯O and O—H⋯N hydrogen bonds
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