Structural interpretation of optical properties and ion transport mechanism in mixed valent Pr containing nanoceria

Microstructure, optical and ionic transport properties of chemically derived Ce1-xPrxO2-delta (0.05 <= x <= 0.2) has been investigated in this work. Rietveld analyses of the X-ray diffraction patterns showed that, microstructural parameters depend on Pr content as well as sintering temperature. The High Resolution Transmission Electron Microscopy together with Rietveld analyses confirmed the cubic fluorite structure of the samples. The Scanning Electron Microscope images showed gradual grain growth clue to sintering. The Energy Dispersive X-ray spectra showed decrease of oxygen content with Pr concentration. The direct optical band gap was found to show a red shift with dopant concentration and sintering temperature. The conductivity has been found to have strong dependency on the oxidation of Pr3+ to Pr4+, impurity, oxygen vacancy concentration, defect association and charge carrier concentration and found to obey Variable Range Hopping phenomenon. The ion dynamics-has been correlated with the structural changes due to Pr doping. (C) 2016 Elsevier Ltd. All rights reserved.