WEDNESDAY 12:00
RARE EARTH DOPED APATITES FOR SOLID OXIDE FUEL CELLS
Gema Gonzalez
Escuela Politécnica Nacional, Dpto. Física, Quito, Ecuador
Instituto Venezolano de Investigaciones Científicas, Centro Ing. Materiales y Nanotecnología, Caracas, Venezuela.
ABSTRACT
Materials displaying high oxide-ion conductivity have attracted considerable interest due to technological applications in solid oxide fuel cells (SOFCs), oxygen sensors and separation membranes. The interest in SOFC devices is mainly related to clean energy conversion.
Zirconia based materials have been considered the best electrolyte up to now. However they operate at very high temperatures, therefore there is a great interest in the development of new materials that operate at lower temperatures. A new classes of oxide-ion conductors, of the apatite-type has recently been proposed.
In the present work rare earth doped apatites has been studied, isostructural with hydroxyapatite biomaterials, with fast oxide-ion conductivity. The materials studied were apatite type substituted with Ce and Sm in different concentrations, additionally the phosphate group was substituted by silicate. The materials were characterized by XRD, FTIR, SEM, complex impedance and luminescence spectroscopy. Conductivity was also measured. It was found that these systems presented a conductivity higher than zirconia based systems, in the temperature range of 600-800 C. The systems with the highest conductivity were SmCe doped apatite (Ce7Sm2(SiO4) and Ce7Sm2(PO4))
These results suggest that the conductivity involves interstitial oxide-ions. Additionally, the high luminescence properties and biocompatibility of these materials give them potential applications in magnetic resonance and bioimaging.