Direct electrochemical reduction of Dy _2O _3 in CaCl _2 melt

摘要

The electrochemical reduction of Dy _2O _3 in CaCl _2 melt was studied. The cyclic voltammetry, chronoamperometry, AC impedance and constant voltage electrolysis were employed. A single cathodic current peak in the cyclic voltammogram and one response semicircle in the AC impedance spectrum were observed, supporting a one-step electrochemical reduction mechanism of Dy _2O _3. No intermediates were observed by XRD, which confirmed the following electrochemical reduction sequence: Dy _2O _3 → Dy. The charge transfer resistances and the activation energies involved in the electrochemical reduction step of Dy _2O _3 were obtained by simulating the AC impedance spectra with equivalent circuits. The electrochemical reduction reaction of Dy _2O _3 is controlled by the charge transfer process at a low voltage range and by the diffusion process at a high voltage range.