Defect structure of YSZ and its influence on ionic conductivity
Stabilized zirconia ceramics have been the subject of extensive scientific research owing to the diverse technological applications these materials find as fuel cells, oxygen sensors, and artificial diamonds. Despite this attention, a number of questions remain to be resolved, including the temperature and concentration dependence of the structural disorder and its interrelationship with the high ionic conductivity which underlies many of the industrial uses of these systems. Analysis of both Bragg and diffuse neutron scattering using SXD at ISIS has identified the three principle types of defect on the anion deficient fluorite lattice. For low defect concentrations the lattice exhibits a tetragonal distortion, but oxygen vacancies stabilize the cubic structure. Isolated mono-vacancy clusters become mobile at elevated temperature, and these are responsible for the high ionic conductivity. Oxygen vacancies form pairs, and as the yttrium content increases, these di-vacancy clusters form static aggregates, eventually leading to a decrease in the ionic conductivity.
Goff JP, Hayes W, Hull S, Hutchings MT and Clausen KN
Phys. Rev. B 59, 14202 (1999). http://dx.doi.org/10.1103/PhysRevB.59.14202