High temperature ionic and electronic conductivity in MgPSZ

The high temperature ionic (sigma(i)) and n-type electronic conductivity (sigma(n)) of 7.5 mol% MgO-doped partially sta-bilized ZrO2 (7.5MgPSZ) were determined using 4 probe total conductivity (in air, 800-1600 C-?), and oxygen concentration cell open circuit voltage measurements (1200-1600 C-?). The latter involved two distinct cell configurations (Al or Cr-based electrodes versus air). The sigma n values of 4.78 x 10(-4) S.cm(-1) at 1600( ?)C (extrapolated to pO(2) = 1 atm) and activation energy of 424.0 kJ.mol(-1) are hereby reported for the first time. The observed ionic conductivity of 0.60 S.cm(-1) at 1600 C-? and activation enthalpy of 119.5 kJ.mol(-1) for the 1400-1600( ?)C temperature range are both within upper ranges reported for other PSZ materials. This high activation enthalpy suggests a strong defect association between oxide-ion vacancies and acceptor dopant, exceeding typical values observed with trivalent dopants. The reasons for wide literature data ranges on ionic transport are discussed taking into consideration the variable phase content, phase composition, and potential non-equilibrium conditions observed in experiments. The specific case of hysteresis in conductivity versus temperature curves is analyzed in detail. Complementary structural and microstructural characterization, besides thermal expansion behavior, are used to support the analysis of electrochemical performance.

Automated summary

The high temperature ionic and n-type electronic conductivity of MgO-doped partially stabilized ZrO2 material were determined. The results showed that the material exhibited high conductivity at high temperature, and had a high activation energy.