CHEMICAL AND PHYSICAL ASPECTS OF THE MISFIT LAYER OXIDES TL-ALPHA[(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 ox ide, Tl-0.41(Sr0.9O)(1.12)CoO2 (Boullay et al. Chem. Mater. 1996, 8, 1 482). In this work, we present a more detailed structural characteriza tion from an additional high-resolution electron microscopy (HREM) stu dy as well as extended X-ray absorption fine structures (EXAFS) from t he Co K edge and the Tl L-III edge. We find a structural picture large ly consistent with the one originally proposed, but much more quantita tive. The work has been extended over a structural family, obtained by replacing Sr by Ca to obtain the title misfit phases. The evolution o f composition and lattice parameters, as well as the magnetic and elec trical transport properties of representative members of the misfit ox ide family, are studied.