Christos Argirusis | PubMed Health

PubMed2005

Enhancement of oxygen surface exchange kinetics of SrTiO(3) by alkaline earth metal oxides.

The oxygen incorporation reaction in undoped SrTiO(3) was investigated by electrical measurements (pressure modulation technique) in the temperature range from 650-920 degrees C and by means of tracer exchange experiments in the temperature range from 458-600 degrees C. The surface of the undoped SrTiO(3) single crystals was modified by alkaline earth metal compounds leading to a tremendous enhancement of the effective surface exchange rate for oxygen incorporation as compared to the uncoated surface.

Kinetics↗

PubMed2004

Lanthanide transport in stabilized zirconias: interrelation between ionic radius and diffusion coefficient.

The diffusion of all stable lanthanides was measured both in calcia stabilized zirconia (CSZ) and in yttria stabilized zirconia (YSZ) in the temperature range between 1,286 and 1,600 degrees C. The lanthanide diffusion coefficients obtained increase with increasing ionic radius. The experimental activation enthalpy of diffusion is near 6 eV for CSZ and between 4 and 5 eV for YSZ and is not strongly affected by the type of lanthanide. The results were correlated with defect energy calculations of the lanthanide diffusion enthalpy using the Mott-Littleton approach. An association enthalpy of cation vacancies with oxygen vacancies of about 1 eV (96 kJ/mol) was deduced in the case of CSZ, while there is no association in the case of YSZ. Furthermore, the change in diffusion coefficients can be correlated to the interaction parameter for the interaction between the lanthanide oxide with zirconia: The higher the interaction parameter, the higher the lanthanide diffusion coefficient.

Journal Article↗