Verwey-Type Charge Ordering and Site-Selective Mott Transition in FeO under Pressure.

The metal-insulator transition driven by electronic correlations is one of the most fundamental concepts in condensed matter. In mixed-valence compounds, this transition is often accompanied by charge ordering (CO), resulting in the emergence of complex phases and unusual behaviors. The famous example is the archetypal mixed-valence mineral magnetite, FeO, exhibiting a complex charge-ordering below the Verwey transition, whose nature has been a subject of long-time debates.

First-Order Phase Transition in BaNiGe and the Influence of the Valence Electron Count on Distortion of the ThCrSi Structure Type.

Structural instability has a strong influence on the understanding of superconductivity in iron-containing 122 phases. Similar to the 122 iron-based high-temperature superconductors, the intermetallic compound BaNiGe undergoes an orthorhombic-to-tetragonal structural phase transition. The compound was prepared by arc-melting mixtures of the elements under an argon atmosphere.

Anomalous compression and new high-pressure phases of vanadium sesquioxide, V2O3.

We report results of a powder x-ray diffraction (XRD) study of vanadium sesquioxide, V2O3, under pressurization in a neon pressure-transmitting medium up to 57 GPa. We have established a bulk modulus value for corundum-type V2O3 of B0 = 150 GPa at B' = 4. This bulk modulus value is the lowest among those known for the corundum-type-structured oxides, e.

Structure induced Yb valence changes in the solid solution Yb(x)Ca(1-x)C2.

The solid solution Yb(x)Ca(1-x)C2 (0 ≤ x ≤ 1) was synthesized by reaction of the elements at 1323 K. The crystal structures within this solid solution, as elucidated from synchrotron powder diffraction data, depend on x and exhibit some interesting features that point to a structure dependent valence state of Yb. Compounds with x ≥ 0.

Structural phase transition study of the morphotropic phase boundary compositions of Na(0.5)Bi(0.5)TiO(3)-PbTiO(3).

Neutron, synchrotron x-ray powder diffraction and dielectric studies have been performed for morphotropic phase boundary (MPB) compositions of the (1-x)Na(1/2)Bi(1/2)TiO(3)-xPbTiO(3) system. At room temperature, the MPB compositions (0.10 View Article and Find Full Text PDF

Mixed LiCo(0.6)M(0.4)PO(4) (M = Mn, Fe, Ni) phosphates: cycling mechanism and thermal stability.

The electrochemical delithiation of LiCo(0.6)M(0.4)PO(4) phosphates (M = Mn, Fe, Ni) was studied by in situ synchrotron diffraction.

Structural behaviour of synthetic Co2SiO4 at low temperatures.

Synthetic Co2SiO4 has an olivine structure with isolated SiO4 groups (space group Pnma) and shows magnetic ordering below 50 K. Single-crystal neutron diffraction was applied to determine precise crystal structure parameters at low temperatures. No structural phase transition was revealed in the temperature range 2.