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Abstract
The equilibrium defect chemistry of Pb(Zr1−xTix)O3 with x = 0.5 has been studied in the oxygenexcess, p-type region by measurement of the equilibrium electrical conductivity over the experimental range 500-700°C and 10−4 < P(O2) < 1 atm, and of the equilibrium oxygen activity as a function of temperature at constant defect concentrations from 600 to 730°C. The results are consistent with there being a higher concentration of trapped holes than of free holes under equilibrium conditions. The enthalpy of formation of free holes is +123 kJ/mol (+1.28 eV) per added oxygen, while that of trapped holes, and hence of the stoichiometric excess of oxygen, is −54 kJ/mole (-0.56 eV). These values indicate that the sum of the depth of the hole-trapping level plus any activation enthalpy for the hole mobility is about 90 kJ/mole (0.9 eV).