Microstructure and charge carrier dynamics in Pr-Sm-Eu triple-doped nanoceria

In this work, microstructural, charge carrier dynamics and dielectric relaxation properties of triple rare earth (Praseodymium, Samarium and Europium) doped ceria nanomaterials have been investigated. The microstructural investigation of the compositions has been done using Rietveld analysis of X-Ray Diffraction data. The total conductivity was found to depend on oxygen vacancy, dopant vacancy interaction and charge carrier concentration. The highest ionic conductivity was obtained for the composition containing Pr = 0.15 and Sm/Eu = 0.075. The temperature dependence of conductivity was found to follow the Vogel-Tammann-Fulcher (VTF) relation. The complex dielectric permittivity and electric modulus have been investigated using Havriliak-Negami function. The shape parameters obtained from modulus spectra and the frequency exponent obtained from conductivity spectra were found to be slightly temperature dependent. The small polaron hopping in localized states and correlated barrier hopping conduction mechanism were confirmed from complex conductivity data. The temperature independent nature of conductivity and relaxation mechanism was confirmed from master plots of modulus and conductivity spectra. The reciprocal temperature dependence of the relaxation times obtained from electrical properties was also found to follow VTF relation. (C) 2016 Elsevier B.V. All rights reserved.