Synthesis of Delafossite-Type Ag_0.9MnO₂ by the Precipitation Method at Room Temperature

A delafossite-type Ag-Mn oxide was successfully synthesized using the precipitation method at room temperature. The delafossite is Ag⁺-deficient and has a chemical composition of Ag_0.9MnO₂. Thermogravimetry of the Ag_0.9MnO₂ delafossite revealed that on heating to 900 °C, it decomposed to Ag and Mn₂O₃ in air and to Ag and Mn₃O₄ under N₂. While cooling to room temperature in air, the delafossite phase reformed from Ag and Mn₃O₄. The reversibility of the decomposition/reformation process is related to the similarity between the delafossite and spinel-type structures, both of which contain an octahedral layer. The reformation process could be used as a new synthetic route to Ag⁺-containing delafossite-type oxides.