Christopher S. Knee

Crystal structure of the ferromagnetic superconductorRuSr2(Gd1.3Ce0.7)Cu2O10 − δby powder neutron diffraction

The 1222-type ferromagnetic, superconducting cuprate, RuSr2(160Gd1.3Ce0.7)Cu2O10xa0−xa0δ, contains RuO6 noctahedra that are rotated 13.4° around the c-axis and tilted nreducing the Cu–O(1)–Ru angle to 168.2° at 295xa0K. The noxygen deficiency δ has been determined as 0.22, indicating na hole doping mechanism, similar to that proposed for GdSr2RuCu2O8, nfacilitates superconductivity.

Syntheses, structures and properties of some osmates(IV,V) adopting the pyrochlore and weberite structures

Samples of the complex osmates Ca2Os2O7, Tl2Os2O7 − nx and Pb2Os2O7 − nx have been obtained by direct reaction of the component oxides in sealed tubes. The structures and compositions of these materials have been investigated by powder neutron and X-ray diffraction at room temperature and through variable temperature studies. Ca2Os2O7 adopts a stoichiometric, orthorhombic weberite structure but the distortion of the OsO6 octahedra and eightfold Ca–O co-ordinations decrease with increasing temperature indicating that this material lies close to the weberite/pyrochlore phase boundary. The lead and thallium phases adopt oxygen deficient, cubic pyrochlore structures under the synthesis conditions employed though no evidence was found of cation non-stoichiometry. Preliminary measurements of the electronic nproperties of weberite Ca2Os2O7 are also reported and discussed in comparison with the lead, thallium, cadmium and mercury osmate pyrochlores.