Effect of crystallinity on proton conductivity in yttrium-doped barium zirconate thin films

The effect of crystallinity on proton conductivity in amorphous, single crystal and polycrystal yttrium-doped barium zirconate (BYZ) thin films grown 120 nm in thickness on amorphous (quartz) and single crystal MgO(100) substrates has been studied. The conductivity was measured in the temperature range of 150 ~ 350 °C. By altering the film deposition temperature, varying degrees of crystallization and microstructure were observed by x-ray diffraction and transmission electron microscopy. The epitaxial BYZ film grown on MgO(100) substrate at 900 °C showed the highest proton conductivity among other samples with an activation energy of 0.45 eV, whereas polycrystalline and amorphous BYZ films showed lower conductivities due to grain boundaries in their granular microstructure.     

A Generalized Plasma and Interpolation Between Classical Random Matrix Ensembles

The eigenvalue probability density functions of the classical random matrix ensembles have a well known analogy with the one component log-gas at the special couplings β=1,2 and 4. It has been known for some time that there is an exactly solvable two-component log-potential plasma which interpolates between the β=1 and 4 circular ensemble, and an exactly solvable two-component generalized plasma which interpolates between β=2 and 4 circular ensemble. We extend known exact results relating to the latter—for the free energy and one and two-point correlations—by giving the general (k ₁+k ₂)-point correlation function in a Pfaffian form. Crucial to our working is an identity which expresses the Vandermonde determinant in terms of a Pfaffian. The exact evaluation of the general correlation is used to exhibit a perfect screening sum rule.     

Water-soluble Self-assembled {Pd84}Ac Polyoxopalladate Nano-wheel as a Supramolecular Host

Polyoxopalladates (POPs) are a class of self-assembling palladium-oxide clusters that span a variety of sizes, shapes and compositions. The largest of this family, {Pd₈₄}^Ac, is constructed from 14 building units of {Pd₆} and lined on the inner and outer torus by 28 acetate ligands. Due to its high water solubility, large hydrophobic cavity and distinct ¹H NMR fingerprint {Pd₈₄}^Ac is an ideal molecule for exploring supramolecular behaviour with small organic molecules in aqueous media. Molecular visualisation studies highlighted potential binding sites between {Pd₈₄}^Ac and these species. Nuclear Magnetic Resonance (NMR) techniques, including ¹H NMR, ¹H Diffusion Ordered Spectroscopy (DOSY) and Nuclear Overhauser Spectroscopy (NOESY), were employed to study the supramolecular chemistry of this system. Here, we provide conclusive evidence that {Pd₈₄}^Ac forms a 1 : 7 host-guest complex with benzyl viologen (BV²⁺) in aqueous solution.