Nonstoichiometry and electrical conduction of CuO

Electrical conductivity, thermoelectric power and weight changes were measured between room temperature and 800 or 1000 degrees C on CuO with varying sintering temperatures to determine nonstoichiometric and defect properties of CuO. CuO was confirmed to be a metal deficient p-type semiconductor with copper vacancies at low temperature. Copper vacancy formation was favored with decreasing sintering temperature indicating the negative enthalpy of the defect generation reaction. Nonstoichiometry in Cu-1-y O was a few percent at 700 - 900 degrees C. Conduction in Cu-1-y O was judged to be due to hopping of charge carriers with an activation energy of 0.1 eV. The band gap energy of CuO, estimated from high temperature intrinsic conductivity was similar to 1.2 eV.