Thermodynamic study of point defects in Cu 2− δO. electrical conductivity measurements at low oxygen partial pressures

Abstract

The electrical conductivity of cuprous oxide has been measured in the temperature range 600–1100°C and for oxygen partial pressures between 10 −7 atm and the oxidation limit of Cu 2− δ O. Oxygen partial pressures lower than 10 −5 atm hav e been obtained either by the partial vacuum technique, the opening of an adjustable leak being tied to the response of an electrochemical gauge placed near the sample, or under a total pressure of 1 atm, the oxygen partial pressure in argon being lowered by passing through an electrochemical pump. The electrical conductivity values, obtained for oxygen partial pressures lower than 10 −5 atm, are in agreement with those measured at higher oxygen partial pressures, using a classical method for obtaining P O 2 . The results obtained may be explained assuming the existence of interactions among defects leading to the formation of complex associates of the type (V' CuV x Cu). At lower P O 2 , the values of the slope 1/ n= ( ∂ ln σ/ ∂ ln P O 2 ) T , lower than 1/8, may be explained by impurity effects or by the prevailing influence of interstitial copper defects.