Defect Interaction Mediated Charge Carrier Dynamics in Gd-Y co-doped Nanocrystalline Ceria

摘要

Defect associates and their interactions with charge carriers influencing the ion dynamics have been discussed for Gd~(3+) and Y~(3+) co-doped nanocrystalline ceria. Detailed Rietveld analysis of the X-Ray Diffraction data confirmed the single phase cubic fluorite structure of the compositions with space group Fm3m. An overall increase of lattice parameter with Gd~(3+) ion concentration has been found. Grain and specific grain boundary conductivity have been evaluated from the complex impedance plots. A higher value of dielectric constant has been found for co-doped sample at 20% doping concentration. The interaction between dopant cations with oxygen vacancies has been found to form different defect associates and defect clusters. The association energy of co-doped samples at 20% doping concentration is found minimum in comparison with the singly doped samples of same concentration. It has also been found that different defect clusters have a significant role on ionic conduction. The correlation among structural parameters, dielectric and conductivity response has been discussed and established.