Microwave technique applied on the hydrothermal synthesis and sintering of calcia stabilized zirconia nanoparticles
|Antonino Rizzuti 1, Cristina Leonelli 1, Anna Corradi 1, Witold Łojkowski 2, Roman Pielaszek 2|
1. Department of Materials and Environmental Engineering University of Modena and Reggio Emilia, Modena 41100, Italy
Calcia as well as di- or-tri-valent oxides stabilized zirconia have received the most attention because of their high oxygen-ion conductivity which combined to their high thermochemical stability makes them as the best candidate for electrochemical devices, such as oxygen sensors, solid oxide fuel cells and oxygen pumps which operate at high temperatures. Main preparation methods of these compounds consist of solid state reaction and also sol-gel route, which require drastic or complex conditions. Hydrothermal treatment appears to be the more simple and less expensive method for the preparation of zirconia nanopowders characterised by high purity and high degree of compositional homogeneity which ensure an appropriate sinterability. The hydrothermal synthesis of calcia zirconia powders has been reported in few papers, never mentioning the possibility to have a microwave-assisted technique. This work is focused on synthesis zirconia nanopowders stabilized by 6 mol% calcium oxide prepared under hydrothermal conditions in combination, for the first time, with microwave technology. Microwave technology is, as diffusely reported, an advantageous tool for the efficient obtainment of inorganic oxides nanoparticles. Hydrolysis of calcium and zirconium nitrates followed by microwave irradiation to reach 200°C for 90 minutes was sufficient to obtain calcia stabilized zirconia as white powders. XRD analysis has evidenced the formation of nanocrystallites of tetragonal symmetry as the main phase with a size of ca 8 nm. The sintering of these nanopowders was performed under microwave irradiation on the sample in the form of a pressed pellet which contains polyvinyl alcohol as binder at a temperature of 1300°C in air. SEM has confirmed that the sample was successfully sintered and the grains have maintained their nanometric size very narrowly dispersed, ranged between 100 and 150 nm.
Presentation: Oral at E-MRS Fall Meeting 2007, Symposium A, by Antonino Rizzuti
See On-line Journal of E-MRS Fall Meeting 2007
Submitted: 2007-05-14 13:44 Revised: 2009-06-07 00:44