High‐Temperature Mechanical Behavior of the Solid‐State Electrolyte: La0.8Sr0.2Ga0.85Mg0.15 O 2.825

The creep behavior of fine‐grained La0.8Sr0.2Ga0.85Mg0.15O2.825 (LSGM-2015) was investigated over the temperature range 1200 to 1300°C in air. The brief creep transients, value of the stress exponent close to unity, absence of deformation‐induced dislocations, and lack of grain‐shape change due to deformation suggest that the creep behavior of LSGM-2015 is controlled by grain boundary sliding accommodated by diffusion. The value of the grain‐size exponent close to two indicates that the rate‐controlling step is lattice diffusion. A comparison of the activation energy for creep with activation energies determined by ionic conductivity, oxygen tracer diffusion, and theoretical predictions reveal that the creep rate of LSGM-2015 is controlled by cation lattice diffusion. © 2000 The Electrochemical Society. All rights reserved.