Phase pure rhombohedral R3¯m$R\bar{3}m$ AgCoO2 delafossite: Rietveld,selected area electron diffraction,X-ray photoemission spectroscopy,and magnetic studies

A p-type rhombohedral AgCoO₂ (S.G. $R\overline{3}m$) reported to form only at pressures greater than 300 MPa at 773 K, is stabilized in pure phase at 0.2 MPa oxygen pressure. Analysis of powder X-ray diffraction pattern by Rietveld and selected area electron diffraction patterns confirms the purity of rhombohedral phase. Core-shell X-ray photoemission spectroscopy studies show that Ag ions are in +1 oxidation state with Co ions largely in +3 state. AgCoO₂ is paramagnetic undergoing super-paramagnetic transition at 44 K. The magnetic moment of Co is 0.001 μB which corresponds to low spin (LS) Co³⁺ along with a small fraction of LS Co⁴⁺ ions.