Microstructural Arrangement and Densification of 10GDC-xTZP Solid Solutions

Solid solutions between tetragonal zirconia polycrystals (TZP) and gadolinia doped ceria with a norminal composition Ce0.9G0.1O1.95(10GDC) powders were studied. The selected composition was 5-15 wt% TZP. The XRD results showed that a complete solid solution between TZP and 10GDC had occurred after sintering at 1500-1600 C, resulting in a progressive decrease of the cubic lattice parameters of the 10GDC. At 1500 C sintering, when the TZP content was increased, porosity was also increased while grain growth was suppressed. However, when the sintering temperature was changed to 1600 C, a rapid grain growth with ananisotropic grain morphologyfor the samples with 10 and 15wt% TZPwas obtained. Vickers hardness was slightly improved with increasing TZP contents when there was no effect of porosity. Fracture toughness was, however, slightly decreased with increasing TZP content. Unfavourable flexural strength was always obtained in all samples mainly due to the anomalous microstructure. The ionic conductivity was not only governed by microstructure but also by lattice deformation due to the solid solution.