X-RAY-ABSORPTION STUDY ON NANOSTRUCTURED ZIRCONIA AND YTTRIA

Nanostructured zirconia and yttria powders with grain sizes between 5 and 30 nm have been studied by extended X-ray absorption fine structur e (Y and Zr K-edges). Due to the high specific surface area of the pow ders (75 to 120 m(2)/g) the fraction of surface atoms is drastically i ncreased. The effective coordination number of the zirconium and yttri um atoms is reduced (up to 40%) in the powders. The decrease of the co ordination number is most obvious in the cation-cation-distances. Full y dense ceramic samples with a grain size of 80 nm have nearly the sam e coordination number compared to samples with conventional grain size s of about 1 mu m.