Chemical and Physical Aspects of the Misfit Layer Oxides Tlα[(Sr1-yCay)O]1+x(CoO2)

Using a combination of microscopy, powder X-ray diffraction, and model building, we recently reported evidence for the first misfit layer oxide, Tl 0.41 (Sr 0.9 O) 1.12 CoO 2 (Boullay et al. Chem. Mater. 1996, 8, 1482). In this work, we present a more detailed structural characterization from an additional high-resolution electron microscopy (HREM) study as well as extended X-ray absorption fine structures (EXAFS) from the Co K edge and the Tl L III edge. We find a structural picture largely consistent with the one originally proposed, but much more quantitative. The work has been extended over a structural family, obtained by replacing Sr by Ca to obtain the title misfit phases. The evolution of composition and lattice parameters, as well as the magnetic and electrical transport properties of representative members of the misfit oxide family, are studied.