DEFECT STRUCTURE AND DIFFUSE-SCATTERING OF ZIRCONIA SINGLE-CRYSTALS AT ELEVATED-TEMPERATURES AND SIMULTANEOUSLY APPLIED ELECTRIC-FIELD

In situ neutron diffraction experiments on cubic zirconia single cryst als were carried out at elevated temperatures and, simultaneously, und er an applied DC electric field, i.e. lasting ionic current. Disorder diffuse scattering of CaO (15 mol%) stabilized ZrO2 (CSZ15) and Y2O3 ( 9.5 mol%, 21 mol%) stabilized ZrO2 (YSZ9.5 and YSZ21, respectively) wa s measured up to 1200 K as function of an applied DC field E less than or equal to 20 V cm(-1) with the E field vector parallel to [100]. At 1000 K, CSZ15 showed a sharpening of the diffuse maxima with increasi ng E field strength; the integrated intensities remained, however, con stant. No such differences were found at 800 and 1200 K. Based on an i nterpretation of the diffuse maxima by microdomains, an ordering proce ss between the microdomains (the correlation length increases from 25 Angstrom at RT to 60 Angstrom at 1000 K) is supported by an enhanced i onic motion at high temperatures. On the other hand the higher mobilit y of the oxygen vacancies at 1200 K acts to destroy the microclusters and leads to a subsequent loss of correlation between them. The equiva lent measurements with YSZ showed no significant changes of diffuse in tensity distributions indicating a different order/disorder behaviour.