Mechanosynthesis, Radiation-Thermal Modification and Characterization of Nanostructured Scandia Stabilized Zirconia Ceramics

SSZ-based ceramics were obtained by sintering of nanopowders derived at room temperature by mechanochemical synthesis from refined technical grade ZrO2 nano-precursors. RT-treatment by 2.5 MeV electrons up to 1563 K was used for the modification of ceramics. Powders and ceramics were characterized by XRD, Raman, SEM and EDS, TEM, SIMS techniques. The phase composition of Zr0.89Sc0.1Ce0.01O1.95 ceramics was very close to cubic structure but better fitting of XRD patterns was obtained for rhombohedral lattice. Conductivity of solid electrolytes for IT SOFC was studied by complex impedance method. To stabilize cubic structure and increase conductivity at operation temperature of To ∼ 1000 K, the composition of SSZ solid electrolyte was optimized by addition of yttria and sintering aids. The interaction of admixtures with minor dopants leading to intergrain phase was revealed. During fast sintering, ceramics keep a memory about inhomogeneous disordered solid solutions in a form of nanostructuring. Conductivity data indicate nanostructuring of ceramics too: activation energies of bulk and grain boundary conductivities are close (Eb ∼ 0.9 eV, Egb ∼ 1.05 eV). Annealing of ceramics at high temperatures increases conductivity at To and promotes grain growth.