Effects of synthesis methods on stability and sintering of praseodymium-(cubic Ca-ZrO2) solid solution

Effect of synthesis method on stability and sintering of praseodymium cubic CaZrO2 solid solution was studied in this paper. Samples in a molar composition (ZrO2)0.7(CaO)0.2(Pr2O3)0.05 were prepared by ceramic method (CE) and several sol-gel methods: colloidal method (CG), protected gel route (GE), citrate method (CI) and polymeric method (PG). DTA-TG analysis was carried out on all samples. The thermal treatment was designed to stabilise cubic zirconia before sintering in all samples. Fired powders were characterised by XRD, crystallite size, concentration of metastable zirconia and SEM-EDX. Powders which cubic zirconia had been stabilised were sieved at 40 μm, uniaxially pressed at 20 MPa and fired at 1450 °C/24 h. The obtained compacts were checked by XRD, SEM-EDX, density measurements, Vickers hardness, complex impedance spectroscopy and lattice parameters calculated by Rietveld method. Pr(Ca-cubic zirconia) solid solution is remained at sintering conditions. Results indicate that ceramic sample with lower porosity than gels samples present better densification and microhardness. Colloidal samples with large open porosity present bad sintering behaviour. Conductivity is associated with reactivity: samples, such as ceramics or colloidal samples, with cubic zirconia single phase present the lower resistance contribution.