Electrical conductivity at high temperature and thermodynamic study of point defects in single crystalline cuprous oxide

Abstract

In order to follow the variation of point defect interactions in relatively concentrated solutions we have studied the electrical conductivity of cuprous oxide in the range of temperature 650–1100°C and for oxygen partial pressures greater than 10 −6 atm. The P 1 π O 2 dependence of the conductivity varied non linearly from about n = 8 for P o 2 close to 10 −6 atm. to lower values of n with increasing oxygen partial pressure. The activation enthalpy of conductivity determined in these ranges of temperature and oxygen partial pressure has been found to be also a function of temperature and varied between 12 and 17 kcal mol −1. The interpretation of these results has permitted us to show that the departure from linearity of the plots of log σ = ƒ(log P 0 2 ) or log σ = ƒ( l T ) excludes the existence of an ideal solution of ionized and non-ionized copper vacancies as was proposed previously in the literature. To explain these results it is possible to take into account a partially disordered distribution of these defects. It is shown that the increase of interactions and consequently the variation of the electrical conductivity as a function of the thermodynamic parameters, may be simulated by an ideal solution including new charged species of the type ( V' Cu V x Cu).