Current-voltage relation and charge distribution in mixed ionic electronic solid conductors

Abstract

Current-voltage relation and charge distribution in mixed ionic electronic solid conductors (MC) are evaluated for dc steady state conditions. Explicit dependence of the electronic and ionic currents on the applied voltage, V, are given for two models: (I) for a MC with a large and uniform ion disorder as, e.g., in δ-Bi 2O 3, doped CeO 2− x , stabilized and reduced ZrO 2 or α-AgI and (II) for a MC with equal concentrations of quasifree electrons and mobile ions as, e.g., in CeO 2− x . The composition of the current in model I depends on V. It is mainly electronic for V close to the polarization voltage and is mainly ionic for V → 0. In model II the current is mainly electronic. In model I the concentration of electrons, n, is not uniform when the MC is in contact with a nonunifonn surrounding. Furthermore, n and the stoichiometry depend both on V. When electrons are present dominantly in one side and holes in the other side of a MC, a p- n quasijunction is formed which depends on the applied voltage V. The charge distribution for V = 0 and for V equals the polarization voltage, is calculated.