Electron microscopy studies of W18O49. 1. Crystals formed by gaseous reduction of WO3

W₁₈O₄₉ samples were prepared by reduction of WO₃ crystals at various temperatures (at about 1170, 1270, and 1370K) by equilibration with a gaseous buffer of controlled oxygen pressure. The samples were studied by high-resolution electron microscopy. The results show that an amorphous phase is an intermediary step in the formation of W₁₈O₄₉. Defects are very rarely observed in as-reduced W₁₈O₄₉, which differs in this respect from other tungsten oxides. Apart from twinning, however, three types of extended defects have been observed occasionally, and these are interpreted and discussed.     

The first three anisotropy constants of nickel

The technique of ferromagnetic resonance at 23 GHz has been used to determine the first three anisotropy constants of pure Ni down to 4.2K. A temperature and orientation dependent linewidth has also been observed.     

Nonlinear pressure dependence of the interaction potential of dense protein solutions

The influence of pressure on the structure and protein-protein interaction potential of dense protein solutions was studied and analyzed using small-angle x-ray scattering in combination with a liquid state theoretical approach. The structural as well as the interaction parameters of dense lysozyme solutions are affected by pressure in a nonlinear way. The structural properties of water lead to a modification of the protein-protein interactions below 4?kbar, which might have significant consequences for the stability of proteins in extreme natural environments.     

X‐ray Raman spectroscopy of lithium‐ion battery electrolyte solutions in a flow cell

The effects of varying LiPF₆ salt concentration and the presence of lithium bis(oxalate)borate additive on the electronic structure of commonly used lithium‐ion battery electrolyte solvents (ethylene carbonate–dimethyl carbonate and propylene carbonate) have been investigated. X‐ray Raman scattering spectroscopy (a non‐resonant inelastic X‐ray scattering method) was utilized together with a closed‐circle flow cell. Carbon and oxygen K‐edges provide characteristic information on the electronic structure of the electrolyte solutions, which are sensitive to local chemistry. Higher Li⁺ ion concentration in the solvent manifests itself as a blue‐shift of both the π* feature in the carbon edge and the carbonyl π* feature in the oxygen edge. While these oxygen K‐edge results agree with previous soft X‐ray absorption studies on LiBF₄ salt concentration in propylene carbonate, carbon K‐edge spectra reveal a shift in energy, which can be explained with differing ionic conductivities of the electrolyte solutions.     

Electrical conductivity and high resolution electron microscopy studies of WO3−x crystals with 0 ≤ x ≤ 0.28

WO_3?x crystals with 0 ≤ x ≤ 0.28 have been studied by means of HREM and electrical conductivity measurements. Semiconducting behavior with andE_a of the order 0.06 eV was observed for crystals which, according to the HREM study, contained {102}CS planes (x ? 0.03). Plots of conductivity vs1–T for WO₃ and WO_3?x containing disordered {102}CS planes are also presented. Metallic behavior was found for crystals with ordered {103}CS planes (x ? 0.11), for W₁₂O₃₄ (x = 0.167), and for W₁₈O₄₉ (x = 0.28).     

Accommodation of oxygen loss in WO3 equilibrated with CO + CO2 buffers

Tungsten trioxide reduced at about 1270 K by means of controlled atmospheres (P₀₂ = 3.7 · 10^?8 to 1.7 · 10^?13 atm) was studied by high resolution transmission electron microscopy, electron diffraction, and X-ray powder diffraction. The accommodation of oxygen loss in the parent WO₃ lattice in the range WO₃ to WO_2.72 was clarified. The results indicate a solid state mechanism. Intergrowth has been found to take place between several of the structural types that occur in this composition range. The intergrowth features include directional changes in shear plane arrays (“swinging shear planes”). Details of the structural variation with the oxygen content are reported. Ordered shear planes on {102} directions were found to stabilize the orthorhombic WO₃ parent lattice at room temperature. W₂₄O₆₈ has been prepared in a fairly well-defined state.