Titanium local environment and electrical conductivity of TiO2-doped stabilized tetragonal zirconia

Solid state reactions in the ZrO2-Y2O3-TiO(2)system have been studied and t he solid solubility limit of TiO2 in yttria stabilized tetragonal zirconia Y-TZP has been stablished. Structural characterization was carried out by X RD studies, and the changes in local structures with increasing TiO2 in ytt ria stabilized tetragonal zirconia was analyzed for the first time by EXAFS and XANES measurements. The XANES results indicate a displacement of Ti io ns from the center of symmetry with increasing titania content leading to a ssume a non randomly substitution of Ti4+ on Zr4+ sites in the tetragonal z irconia lattice. From the Ti-O and Ti-Ti measured distances, it has been as sumed that the found electrical conductivity decrease with increasing titan ia content was due to both a trapping of the oxygen ion vacancies at Ti ion s (Ti'(Zr) Vo) and the formation of more complex associations like (Ti'(Zr) Vo Ti'(Zr) Vo), which giving rise to a reduction in the global concentrati on of moving oxygen vacancies. (C) 2000 Kluwer Academic Publishers.