Chemistry of noble metal oxides. I. Syntheses and properties of ABO2 delafossite compounds

Article abstract of DOI:10.1021/ic50098a011

Syntheses of the new members of the delafossite-type oxides PtCoO₂, PdCoO₂, PdCrO₂, PdRhO₂, AgCoO₂, AgGaO₂, AgScO₂, AgInO₂, and AgTlO₂ and single-crystal growth of PtCoO₂, PdCoO₂, CuCoO₂, CuFeO₂, AgCoO₂, AgGaO₂, AgInO₂, and AgTlO₂ are reported. Accurate cell dimensions for 17 members of the delafossite series are given along with thermal stability data for many of the compounds. Palladium and platinum are shown to be formally monovalent in PdCoO₂, PdCrO₂, PdRhO₂, and PtCoO₂. The platinum composition appears also to exist over a compositional range Pt_1+nCo₂-_(2n/3)O₄ where n = 0.6-0.8. In this latter series, platinum is presumably divalent. Thus, the Pt compound may contain either Pt⁺, Pt²⁺, or a mixture of the monovalent and divalent ions. Closed systems are shown to be effective in preparing ternary noble metal oxides which cannot generally be prepared under autogenous pressure.