Hydrothermal Synthesis of AgCrO₂ Delafossite in Supercritical Water: A New Single-Step Process

It was previously reported that the synthesis of silver based delafossites as pure phases is challenging and requires more often delicate preparations as ion-exchange rather than simple solid state reaction or hydrothermal synthesis. For the first time, polycrystalline AgCrO2 samples are synthesized by a one-step reaction between Ag2O and Cr(OH)3 in supercritical water conditions (400 °C, 40 MPa) using K2Cr2O7 as an oxidizing agent via a hydrothermal method. K2Cr2O7 is proved to be a good oxidizing agent, which avoids the formation of metallic silver and increases the solubility of precursors that lead to the formation of AgCrO2. The quality of the so-obtained compound is checked by structural as well as magnetic and optical properties characterizations.