Dense scales of the tetragonal phase were studied, at temperatures of between 1100 and 1300C, by using the so-called interruption kinetic (Rosenberg) method. By assuming that O vacancies were the predominant defects, estimates were made of the O self-diffusion coefficient in this oxide at its lower limit of stability. The results were described by:

D (cm2/s) = 0.0022 exp[-140(kJ/mol)/RT]

The studies also showed that the maximum non-stoichiometry, x, in tetragonal ZrO2-x was small and was equal to about 0.03 at temperatures ranging from 1000 to 1300C.

B.Oberlander, P.Kofstad, I.Kvernes: Materialwissenschaft und Werkstofftechnik, 1988, 19[6], 190-3