Praseodymium doped ceria as electrolyte material for IT-SOFC applications

Abstract

Praseodymium-doped ceria (PDC, Ce0.9Pr0.1O2) electrolyte material for intermediate temperature solid oxide fuel cells (IT-SOFCs) has been successfully synthesised by EDTA-citrate method. From X-Ray diffraction (XRD), fluorite structure along with a crystallite size of 5.4 nm is obtained for PDC nanopowder calcined at 350 degrees C/24 h. Raman spectroscopy confirmed the structure, presence of oxygen vacancies with the manifestation of the main peak at 457 cm(-1) and with a secondary peak at 550 cm(-1). From Transmission Electron Microscopy (TEM) analysis, the average particle size is around 7-10 nm and selected area electron diffraction (SAED) patterns further confirmed the fluorite structure of PDC nanopowder. The PDC nanopowder displayed a BET surface area of 65 m(2)/g with a primary particle size of similar to 13 nm (calculated from BET surface area). Dilatometer studies revealed a multi-step shrinkage behaviour with the multiple peaks at 522, 1171 and 1461 degrees C which may be originated due to the presence of multiple size hard agglomerates. The PDC electrolyte pellet sintered at 1500 degrees C displayed an ionic conductivity of 1.213E-03 S cm(-1) along with an activation energy of 1.28eV. Instead of a single fluorite structure, XRD of sintered PDC pellet showed multiple structures (Fluorite structure (CeO2) and cubic structure (PrO2).