Ionic conductivity, structural and thermal properties of pure and Sr2+ doped Y2Ti2O7 pyrochlores for SOFC

In the present study, SrO doped Yttrium titanate pyrochlore was synthesized using solid state reaction technique. The sintering characteristics, crystal structure, thermal and conductivity behavior of doped and undoped pyrochlores have been studied to find their suitability in solid oxide fuel cells (SOFC). The as-prepared samples were characterized using X-ray diffraction (XRD), Fourier-Transform-Infrared spectroscopy (FT-IR), thermal-gravimetric analysis (TGA) and ac conductivity up to 900 degrees C. The results are discussed in light of oxygen vacancy formation and structural disordering. Undoped and doped yttrium titanate with SrO (x = 0.1) exhibits single Y2Ti2O7 phase with relative density of 94%. It was observed that further doping of SrO (x = 0.2-0.4) leads to formation of Y2Ti2O7 phase along with SrTiO3 phase. Excessive SrO (x = 0.4) results in increase in ionic conductivity to 1.50 x 10(-1) S cm(-1) whereas it impedes the densification process with relative density of 85%. (C) 2011 Elsevier Masson SAS. All rights reserved.