The Organization of Two Soft (Cu2Ө, Ni2Ө) Metal Centers in Heterotrinuclear Complexes of a Macrocyclic Ligand by Cocomplexation with Ba2Ө

The short distances between the two transitionmetal centers in the trinuclear complexes 3 are caused by cocomplexation of Ba2Ө: Cu2Ө:...Cu2Ө 3.50, Ni2Ө ...Ni2Ө 3.42 Å. The macrocyclic ligand is formed as the complex 2 from o-phenylenediamine and 1 in the presence of Ba2Ө. Complexes 3, in turn, are obtained by treatment of 2 with copper or nickel acetate

The atomic surface structure of SrTiO3 (001) studied with synchrotron X-rays

The atomic surface structure of single terminated SrTiO3(0 0 1) (1 × 1) is investigated employing surface X-ray diffraction. In order to obtain these surfaces a special treatment is needed consisting of chemical etching and annealing. Since this is done in an aqueous and subsequently oxygen environment, after which the crystals are kept at ambient conditions, the surface is studied in air. Crystal truncation rods are measured and several models that are proposed in literature in recent years are tested against the experimental data. These models include surface rumpling, low temperature-like distortions, strontium adatom and lateral displacement distortions for both TiO2 and SrO-terminated surfaces. None of these models represents the data very accurately. A much better fit to the experimental results is obtained by using a model in which a TiO2-terminated crystal is covered by an oxygen layer

Interface structure of SrTiO3-LaAlO3 at elevated temperatures studied in-situ by synchroton x-rays

The atomic interface structure between SrTiO3 and LaAlO3 was studied at elevated temperatures employing in situ surface x-ray diffraction. The results at 473 K indicate that the lattice distorts significantly in two ways. First, the interatomic distances between the cations across the interface become as large as 4.03(2) Å. Second, the TiO6 octahedra at the interface contract their principal axis along the surface normal considerably and the Ti displaces off center. These distortions can be ascribed to the charge inbalance introduced by the change in atomic species across the interface and to a Jahn-Teller effect. The latter distortion suggests the presence of extra electrons at the interface, which is important for understanding the electronic properties of this system