DEFECT STRUCTURE OF ZrO₂ -Y₂O₃ ( Y₂O₃ -3,12,30 MOL%) SINGLE CRYSTALS. NEUTRON AND X-RAY INVESTIGATION. V.A. Sarin¹, E.E. Rider¹, D. Hohlwein², W. Depmeier³, H. Bessert³, F. Frey⁴, K. Hroudil⁴. ¹FLNP, JINR, Dubna, Russia; ²Institute fur Kristallographie, Uni Tubingen, BRD; ³Institute fur Mineralogie, Uni Kiel, BRD; ⁴Institute fur Kristallographie, Uni Munchen, BFD

Statistic defect structures of tetragonal and cubic yttria stabilized zirconia were investigated by X-ray and neutron methods using Bragg diffraction and diffuse scattering.

ZrO₂+3 mol% Y₂O₃ . Space group P42₁/nmc. Crystallographic relations between components of twins are proposed to be two 900 rotation axes a and b (a). There are diffuse scattering in reciprocal space in directions between splitted spots from different components of twins. These data are interpreted as due to domain microstructure and the internal stresses resulting from cubic-tetragonal transformation and differences between the fluorite cubic and tetragonal structures.

ZrO₂+12 and 30 mol% Y₂O₃. Space group Fm3m. From neutron diffuse scattering there were found the very similar experimental pictures. There are some satellite diffuse maxima with a wave vector (0.4, 0.4, (0.8)) and broad diffuse bands. But their integrated intensities are different for 12 and 30 mol% Y₂0₃. There is no such diffuse scattering for 3 mol% Y₂O₃.

For interpretation of defect structures of yttria stabilized zirconia two approaches connected with Bragg diffraction data and diffuse scattering will be compared and opportunities of neutron steady beam (flat cone diffractometer E2, BENSC, Berlin) and time of flight methods (DN2 & HRFD, IBR-2, FLNP, Dubna) will be discussed. [s1]