In situ EPR studies of chemical diffusion in oxides

Electron paramagnetic resonance (EPR) was applied as an in situ technique at high temperatures up to 1000 degrees C for defect chemical and transport studies of ionic and mixed conductors. Equilibrium absorption intensities were examined as a function of oxygen partial pressure temperature and doping content for the model materials Y2O3-stabilized ZrO2 and Fe-doped SrTiO3. By this novel use of EPR in the field of solid state ionics, chemical diffusion coefficients and surface exchange coefficients of oxygen can be measured without any probe electrodes under diffusion conditions. This study moreover confirmed the ability to depress substantially the chemical diffusivity by using deep dopants such as Mn or Fe.