High pressure solid electrolyte redox experiments: Application to silver iodide

To investigate the chemical effects of electron transfer in ionic materials at high pressures and to explore the feasibility of performing redox reactions at high pressures, we performed a series of electrochemical investigations of the solid electrolyte silver iodide (AgI) at pressures up to 10 GPa and at room temperature in a hydrothermal diamond anvil cell. A controlled-voltage power supply connecting two electrodes in the sample chamber forced the dissociation of AgI into component elements. Experiments were performed under non-hydrostatic conditions as well as under quasi-hydrostatic conditions. The progression of the reactions was measured by image processing of movie files generated during the reactions. The rate of the dissociation reaction increased as a function of voltage, and decreased as a function of pressure. Potential applications of these experiments include methods to investigate the effect of pressure on electrochemical processes, point defect creation and transport behavior, redox reactions under pressure, transport and reactions in the deep Earth, and innovative technological potential, such as producing miniature electronic devices at high pressures.