NEUTRON-DIFFRACTION STUDY OF TETRAGONAL ZIRCONIAS CONTAINING TETRAVALENT DOPANTS

In tetragonal zirconia, the cation is coordinated by two interpenetrat ing tetrahedra of oxygen ions, implying two different cation-oxygen bo nd lengths. Neutron powder diffraction was used to study tetragonal Zr O2-2 mol% Y2O3 incorporating various amounts of the different tetraval ent ions Ge, Ti, Sn and Ce. Precise and accurate values for the lattic e parameters and the variable oxygen position parameter have been obta ined, and from these the bond lengths derived. The results are compare d with those from an earlier X-ray and Raman study on the same materia ls. Of interest are the confirmation of the increase in cell volume oc curring when Zr is replaced by the smaller Sn ion, and the observation of departures from Vegard's law in the case of substitution of Zr by Ti.