Effect of nickel substitution on defect chemistry, electrical properties, and dimensional stability of calcium-doped yttrium chromite

摘要: Abstract The effect of nickel substitution on defect chemistry, electrical properties, and dimensional stability calcium-doped yttrium chromite was studied for use as an interconnect material in high temperature solid oxide fuel cells (SOFCs). compositions Y 0.8 Ca 0.2 Cr 1 − x Ni x O 3 ± δ (x = 0–0.15), prepared using the glycine nitrate process, showed single phase orthorhombic perovskite structures over a wide range oxygen partial pressures (4.6 × 10 − 20  atm ≤  p 2  ≤ 0.21 atm at 900 °C). X-ray diffraction (XRD) analysis indicated that most ions replacing chromium are divalent act acceptor dopants, leading to substantial increase conductivity. In particular, conductivity 900 °C air increased from 10 S/cm 34 S/cm with 15% substitution, charge carrier density confirmed by Seebeck measurements, which validated predominant 2+ oxidation state. A point model derived, relationship between pressure successfully fitted into proposed model. modeling results improves toward reduction suppresses vacancy formation, significantly reducing environment. 0.85 0.15 atmosphere (  = 10 − 17  atm) 5.8 S/cm, more than order magnitude higher CrO (0.2 S/cm). Improved further dilatometry measurements showing reduced isothermal “chemical” expansion, expansion pO decreased 0.07% 0.03% . Based these results, enhanced performance mechanical integrity is expected SOFC operating conditions.