Synthesis, Structure and Magnetic Properties of NiFe3O5

A new CaFe3O5-type phase NiFe3O5 (orthorhombic Cmcm symmetry, cell parameters a = 2.89126(7), b = 9.71988(21) and c = 12.52694(27) Å) has been synthesised under pressures of 12-13 GPa at 1200 °C. NiFe3O5 has an inverse cation site distribution and reveals an interesting evolution from M2+(Fe3+ )2Fe2+O5 to Fe2+(M2+ 0.5Fe3+ 0.5)2Fe3+O5 distributions over three distinct cation sites as M2+ cation size decreases from Ca to Ni. Magnetic susceptibility measurements show successive transitions at 275, ~150, and ~20 K and neutron diffraction data reveal a series of at least three spin-ordered phases with evolving propagation vectors k = [0 0 0] [0 ky 0]  [½ ½ 0] on cooling. The rich variety of magnetically ordered phases in NiFe3O5 likely results from frustration of Goodenough-Kanamori exchange interactions between the three spin sublattices, and further interesting magnetic materials are expected to be accessible within the CaFe3O5-type family.

On the Lithium Distribution in Halide Superionic Argyrodites by Halide Incorporation in Li7−xPS6−xClx

<p>Superionic lithium argyrodites are attractive as solid electrolytes for all-solid-state-batteries. These materials of composition Li₆PS₅X (X = Cl, Br, and I) exhibit structural disorder between the X⁻/S²⁻ positions, with higher disorder realizing better Li⁺ transport. Further replacement of the sulfide by chloride anions (for the series Li₇_−xPS₆_−xCl_x) has been shown to increase the ionic conductivity. However, the underlying changes to the lithium substructure are still relatively unknown. Here we explore a larger range of nominal halide compositions in this material from x = 0.25 to x = 1.5 and explore the changes with neutron diffraction and impedance spectroscopy. The replacement of S²⁻ by Cl⁻causes a lowered average charge in the center of the prevalent Li⁺ “cages”, which in turn causes weaker interactions with Li⁺ ions. Analysis of neutron diffraction data reveals that the increased Cl⁻ content causes these clustered Li⁺ “cages” to become more interconnected, thereby increasing Li⁺ conductivity through the structure. This study explores the understanding of the fundamental structure–transport correlations in the argyrodites, specifically structural changes withinthe Li⁺ ion substructure upon changing anionic charge distribution.</p>

On the Lithium Distribution in Halide Superionic Argyrodites by Halide Incorporation in Li7−xPS6−xClx

<p>Superionic lithium argyrodites are attractive as solid electrolytes for all-solid-state-batteries. These materials of composition Li₆PS₅X (X = Cl, Br, and I) exhibit structural disorder between the X⁻/S²⁻ positions, with higher disorder realizing better Li⁺ transport. Further replacement of the sulfide by chloride anions (for the series Li₇_−xPS₆_−xCl_x) has been shown to increase the ionic conductivity. However, the underlying changes to the lithium substructure are still relatively unknown. Here we explore a larger range of nominal halide compositions in this material from x = 0.25 to x = 1.5 and explore the changes with neutron diffraction and impedance spectroscopy. The replacement of S²⁻ by Cl⁻causes a lowered average charge in the center of the prevalent Li⁺ “cages”, which in turn causes weaker interactions with Li⁺ ions. Analysis of neutron diffraction data reveals that the increased Cl⁻ content causes these clustered Li⁺ “cages” to become more interconnected, thereby increasing Li⁺ conductivity through the structure. This study explores the understanding of the fundamental structure–transport correlations in the argyrodites, specifically structural changes withinthe Li⁺ ion substructure upon changing anionic charge distribution.</p>

Incommensurately modulated crystal structure of α′ (O′3)-type sodium cobalt oxide Na x CoO2 (x ∼ 0.78)

A single-phase sample of α′ (O′3)-type layered sodium cobalt oxide Na x CoO2 (x ∼ 0.78) was prepared and its incommensurately modulated crystal structure was analyzed using the (3+1)-dimensional superspace approach to the powder neutron diffraction data. The crystal structure of the cobaltate is accurately described based on the superspace group C2/m(α0γ)00, wherein the positions of Na atoms are most significantly modulated in the monoclinic a direction to form an ordered arrangement. Such a displacive modulation causes a quasi-periodic shift of Na atoms from the centers of the NaO6 polyhedra between undulated CoO2 sheets, changing the form of the NaO6 polyhedron from an octahedral coordination (O) to a trigonal prismatic (P) one, via an intermediate capped trigonal prismatic NaO7 coordination (C). At the positions where the Na atoms are most significantly shifted, the neighboring Na atoms are located at almost touching distances. However, the occupation factor of Na atoms becomes zero at such positions, yielding Na-deficient sites V Na, sandwiched either between C and P, or C and C-type polyhedra.

Preliminary results of neutron and X-ray diffraction data collection on a lytic polysaccharide monooxygenase under reduced and acidic conditions

Lytic polysaccharide monooxygenases (LPMOs) are copper-center enzymes that are involved in the oxidative cleavage of the glycosidic bond in crystalline cellulose and other polysaccharides. The LPMO reaction is initiated by the addition of a reductant and oxygen to ultimately form an unknown activated copper–oxygen species that is responsible for polysaccharide-substrate H-atom abstraction. Given the sensitivity of metalloproteins to radiation damage, neutron protein crystallography provides a nondestructive technique for structural characterization while also informing on the positions of H atoms. Neutron cryo-crystallography permits the trapping of catalytic intermediates, thereby providing insight into the protonation states and chemical nature of otherwise short-lived species in the reaction mechanism. To characterize the reaction-mechanism intermediates of LPMO9D from Neurospora crassa, a cryo-neutron diffraction data set was collected from an ascorbate-reduced crystal. A second neutron diffraction data set was collected at room temperature from an LPMO9D crystal exposed to low-pH conditions to probe the protonation states of ionizable groups involved in catalysis under acidic conditions.

The structure of oxide glasses studied by high-energy x-ray diffraction

The use of high‑energy x‑ray diffraction techniques with the latest generation synchrotron sources has created new approaches to study quantitatively the structure of noncrystalline materials. Recently, this technique has been combined with neutron diffraction at pulsed source to provide more detailed and reliable structural information not previously available. This article reviews and summarises recent results obtained from the high energy x‑ray diffraction on several oxide glasses, SiO2, B2O3 and PbSiO3, using bending magnet beamlines at SPring‑8. In particular, it addresses the structural models of the oxide glasses obtained by the reverse Monte Carlo (RMC) modelling technique using both the high energy x‑ray and neutron diffraction data.

Neutron Diffraction Study on the Magnetic Structure of 153EuMnO3-δ: One Way to Assess the Magnetic Structure of EuMnO3-δ

Owing to the strong neutron absorption of 151Eu, 151Eu free 153EuMnO3-δ has been synthesized to collect the neutron diffraction data for analyzing the magnetic structure of EuMnO3-δ. The obtained neutron diffraction data of 153EuMnO3-δ indicates that the magnetic diffraction peaks corresponding to cAAFM (canted A-type antiferromagnetic) phase can be observed, but the magnetic diffraction peaks corresponding to expected ICAFM (incommensurate antiferromagnetic) phase may be too weak to be observed.