Electrochemical behaviors of single microcrystals of iron Hexacyanides/NaCl solid solution.

Solid-state solution with excellent ionic conductivity and redox activity has potential applications in electrochemical microdevices, such as transistors, switches, sensors, and actuators, due to its controllable assembly, integration, and package in microchips. In this paper, we present an electrochemical method to synthesize single microcrystals of an iron hexacyanides/NaCl solid solution and to assemble them into microdevices based on scanning electrochemical cell microscopy. The redox behaviors of the single microcrystals were investigated systematically, especially in the "all-in-solid-state", that is, without exposure to any external liquid environment. The unique metal/solid solution interface has similar electrochemical properties as the conventional metal/liquid solution interface. The apparent concentration of ion hexacyanides (1.05 × 10(-3) mol/L), the diffusion coefficient of the counterion Na(+) (8.05 × 10(-8) cm(2)/s), and the electron transfer rate in the lattice (1.22 × 10(-4) cm/s) were evaluated from the data obtained through all-in-solid-state cyclic voltammetry and electrochemical impedance. All the results are comparable to the conventional metal/solution theory of electrochemistry.