Influence of gadolinium doping on the structure and defects of ceria under fuel cell operating temperature

Abstract

Correlation between atomic positional shift, oxygen vacancy defects, and oxide ion conductivity in doped ceria system has been established in the gadolinium doped ceria system from X-ray diffraction (XRD) and Raman spectroscopy study at operating temperature (300–600 °C) of Intermediate Temperature Solid Oxide Fuel Cell (IT-SOFC). High temperature XRD data are used to quantify atomic positional shift from mean position with temperature. The Raman spectroscopy study shows additional vibration modes related to ordering of defect spaces (Gd′Ce−V••o)∗ and (2Gd′Ce−V••o)x generated due to association of oxygen vacancies and reduced cerium or dopant cations site (Gd3+), which disappear at 450 °C; indicating oxygen vacancies dissociation from the defect complex. The experimental evidences of cation-anion positional shifting and oxygen vacancies dissociation from defect complex in the IT-SOFC operating temperature are discussed to correlate with activation energy for ionic conductivity. The author S.A.A. wants to acknowledge the financial support from DST, New Delhi, India under project of SR/FTP/PS-106/2009 (G) and UGC under MRP F.N. 41-871/2012. S.K.K. thanks DST, India Nano-Mission Initiative Project SR/NM/NS-42/2009 and UGC, India for the continuous support.