Grain shape effect on dielectric properties and ionic conductivity of Gd-doped ceria

Abstract

Dielectric behaviour and ionic conductivity of nanostructured Ce0.9Gd0.1O2-δ (GDC) are investigated to probe morphology influence of grains on ion transport mechanism at microscopic level. GDC are synthesized in two different morphologies of grains (rod-shape and round-shape particles). TEM study confirmed shape and size; diameter of rods are observed around 20 nm and length are in range of 50-100 nm, while diameter of round particles are found about 10 nm. The dielectric behaviour is studied using the dielectric functions such as dielectric permittivity (ε') and electric modulus (M"). The ionic conductivity is studied by temperature dependent impedance spectra. Both these properties are observed to be finely manipulative by morphology and size. Activation energy of charge carrier relaxation and charge carrier orientation are calculated from impedance spectra and electric modulus spectra and are found to be more in rod-shape GDC. Dielectric relaxation times are also observed to be more for GDC rods. This study provides clear evidence that grain shape and size affect on dopant-oxygen vacancies ineraction, which affect on ion migration and hence ionic conductivity. 1D morphology of grains in oxy-ion conductor has high potential to enhance ionic conductivity. © 2014 VBRI press.