20 research outputs found
CCDC 1567343: Experimental Crystal Structure Determination
No full textRelated Article: Liurukara D. Sanjeewa, Vasile O. Garlea, Michael A. McGuire, Matthias Frontzek, Colin D. McMillen, Kyle Fulle, Joseph W. Kolis|2017|Inorg.Chem.|56|14842|doi:10.1021/acs.inorgchem.7b02024,An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures
CCDC 1567344: Experimental Crystal Structure Determination
No full textRelated Article: Liurukara D. Sanjeewa, Vasile O. Garlea, Michael A. McGuire, Matthias Frontzek, Colin D. McMillen, Kyle Fulle, Joseph W. Kolis|2017|Inorg.Chem.|56|14842|doi:10.1021/acs.inorgchem.7b02024,An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures
Neutron diffraction from aligned stacks of lipid bilayers using the WAND instrument
No full textNeutron diffraction from aligned stacks of lipid bilayers is examined using the Wide-Angle Neutron Diffractometer (WAND), located at the High Flux Isotope Reactor, Oak Ridge, Tennessee, USA. Data were collected at different levels of hydration and neutron contrast by varying the relative humidity (RH) and H2O/D2O ratio from multi-bilayers of dioleoylphosphatidylcholine and sunflower phosphatidylcholine extract aligned on single-crystal silicon substrates. This work highlights the capabilites of a newly fabricated sample hydration cell, which allows the lipid bilayers to be hydrated with varying H/D ratios from the RH generated by saturated salt solutions, and also demonstrates WAND's capability as an instrument suitable for the study of aligned lipid multi-bilayers.</jats:p
On the elusive nature of oxygen binding at coordinatively unsaturated 3d transition metal centers in metal–organic frameworks
No full textLow and ambient temperature binding of oxygen, O2, in MOF-74, CPO-27-M (M = Mn, Co, Ni, Cu, Zn) framework materials remains in the physisorption regime, with energetics very similar to that of nitrogen, N2, sorption.</p
Layered oxychlorides [<tex>PbBiO_{2}</tex>(A = Pb/Bi, B = Fe/Ti) : intergrowth of the hematophanite and sillen phases
No full textAbstract: New layered structures corresponding to the general formula [PbBiO2]A(n+1)B(n)O(3n-1)Cl(2) Were prepared. Pb5BiFe3O10Cl2 (n = 3) and Pb5Bi2Fe4O13Cl2 (n = 4) are built as a stacking of truncated A(n+1)B(n)O(3n-1) perovskite blocks and alpha-PbO-type [A(2)O(2)](2+) (A = Pb, Bi) blocks combined with chlorine sheets. The alternation of these structural blocks can be represented as an intergrowth between the hematophanite and Sullen-type structural blocks. The crystal and-Magnetic structures of Pb5BiFe3O10Cl2 and Pb5Bi2Fe4O13Cl2 were investigated in the temperature range of 1.5-700 K using X-ray and neutron powder diffraction, transmission electron microscopy and Fe-57 Mossbauer spectroscopy. Both compounds crystallize in the I4/mmm space group with the unit cell parameters a approximate to a(p) approximate to 3.92 angstrom (a unit-cell parameter of the perovskite-structure), c approximate to 43.0 angstrom for the n = 3 member and c approximate to 53.5 angstrom for the n = 4 member. Despite the large separation between the slabs containing the Fe3+ ions (nearly 14 angstrom), long-range antiferromagnetic order sets in below similar to 600 K with the G-type arrangement of the Fe magnetic moments aligned along the c-axis. The possibility of mixing d(0) and d(n) cations at the B sublattice of these structures was also demonstrated by preparing the Ti-substituted n = 4 member Pb6BiFe3TiO13Cl2
Investigation of a Structural Phase Transition and Magnetic Structure of Na<sub>2</sub>BaFe(VO<sub>4</sub>)<sub>2</sub>: A Triangular Magnetic Lattice with a Ferromagnetic Ground State
No full textMechanical Activation and Cation Site Disorder in MgAl2O4
No full textThe synthesis and crystallographic site occupancy were investigated for MgAl2O4 with and without mechanical activation of the precursor powders. Heating to 1200 °C or higher resulted in the formation of a single spinel phase regardless of whether the powders were mechanically activated or not. Neutron diffraction analysis was used to determine cation site occupancy and revealed that mechanical activation resulted in a lower degree of cation site inversion compared to the nonactivated materials, which indicated that the powders were closer to thermodynamic equilibrium. This is the first study to characterize the effects of mechanical activation on crystallographic site occupancy in magnesium aluminate spinel using neutron diffraction
Spin Waves in Dirac Semimetal Ca0.6Sr0.4MnSb2 Investigated with Neutrons by the Diffraction Method
No full textThe tunability of Dirac semimetals with antiferromagnetic Mn layers is of great interest. The observed sign change of interlayer magnetic coupling between CaMnBi2 and SrMnBi2 suggests ionic substitution as a potential tuning mechanism. If so, novel behavior near the compensation point could be expected. To explore this, we study a mixed-cation analog, Ca0.6Sr0.4MnSb2, where Bi is replaced by Sb. Conventional inelastic neutron scattering is impractical due to the small crystal size (≈0.28 g) available for compositional studies; however, we find that using a neutron diffractometer with a wide-angle area detector we can obtain a good quality spin-wave signal, which is shaped by energy-momentum conservation and retains spectroscopic information even without direct energy analysis. Spin-wave modeling reveals an interlayer coupling quantitatively similar to SrMnSb2, indicating it is not directly tuned by ionic size and that the sign change in Bi-based compounds likely arises from the observed change in lattice symmetry. Beyond this key insight, our results present an efficient method for parametric and compositional studies of spin dynamics in small crystals
Spin waves in Dirac semimetal CaSrMnSb investigated with neutrons by the diffraction method
No full textWe report neutron diffraction measurements of CaSrMnSb, a
low-carrier-density Dirac semimetal in which the antiferromagnetic Mn layers
are interleaved with Sb layers that host Dirac fermions. We have discovered
that we can detect a good quality inelastic spin wave signal from a small (m ~
0.28 g) single crystal sample by the diffraction method, without energy
analysis, using a neutron diffractometer with a position-sensitive area
detector; the spin-waves appear as diffuse scattering that is shaped by
energy-momentum conservation. By fitting this characteristic magnetic
scattering to a spin-wave model, we refine all parameters of the model spin
Hamiltonian, including the inter-plane interaction, through use of a
three-dimensional measurement in reciprocal space. We also measure the
temperature dependence of the spin waves, including the softening of the spin
gap on approaching the Neel temperature, . Not only do our results provide
important new insights into an interplay of magnetism and Dirac electrons, they
also establish a new, high-throughput approach to characterizing magnetic
excitations on a modern diffractometer without direct energy analysis. Our work
opens exciting new opportunities for the follow-up parametric and compositional
studies on small, ~0.1 g crystals.Comment: 6 pages including 4 figures and bibliography plus 13-page
supplementary with figures S1-S1
Neutron Powder Diffraction Study on the Magnetic Structure of NdPd<sub>5</sub>Al<sub>2</sub>
No full text
