2007 Volume 48 Issue 3 Pages 332-336
The effect of titania doping on tetragonal to monoclinic (t-m) phase transformation of zirconia bioceramics is evaluated by ageing in hot water at 413 K. The examined materials are 3 mol%Y2O3 stabilized tetragonal zirconia polycrystal (3Y-TZP) and 1.5, 3.0 and 7.7 mol%TiO2-doped 3Y-TZP. The t-m phase transformation of 3Y-TZP is accelerated by titania doping in all the specimen examined. However, 7.7 mol%TiO2-doped TZP shows better phase stability than 1.5 or 3.0 mol%TiO2-doped one. This change in phase stability of 7.7 mol%TiO2-doped TZP cannot be simply explained from the difference of grain size or the change in the axial ratio, c⁄a. XRD analysis reveals that the distance between nearest neighbor anion and cation site significantly decreases only in 7.7 mol%TiO2-doped TZP. This result indicates that the binding energy between dopant and oxygen vacancy affects the phase stability as well as the change in the axial ratio, c⁄a.