Mackinawite,tetragonal FeS, has been synthesised by reacting iron with Na2S solutions. A Rietveld structure refinement of X-ray powder diffractipn data, recorded using X-rays monochromated from synchrotron radiationwith a wavelength of 0.6023 A, has been performed. The structure has been refined in the tetragonal sJ'.!lcegroup, P4/nmm, and has the following cell parameters: a = 3.6735(4), c = 5...

Department of Chemistry, University of Cal CA 95616, USA. E-mail: [email protected] Chemical and Engineering Materials Divisi Ridge, Tennessee 37830, USA Laboratoire CRISMAT, ENSICAEN, CNRS U F-14050 Caen, France † Electronic supplementary information tables of crystal structure renements an CIFs, synchrotron X-ray and neutron p plots, additional TEM and elemental an structure diagrams. See D...

A new form of delafossite-type AgCoO2+δ was prepared using ion exchange from Na0.75CoO2 in molten AgNO3-NH4NO3 at 175°C. Its structure was determined by Rietveld refinement from XRD data; it is hexagonal, space group P63/mmc, a = 2.871 and c = 12.222 Å. Its structure differs from previously reported AgCoO2 (R-3m, 3R polytype) by the stacking of Co-O layers; in the new phase the 2H stacking of t...