Ionic conductivity, structural and thermal properties of pure and Sr~(2+) doped Y_2Ti_2O_7 pyrochlores for SOFC

摘要

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 °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 Y_2Ti_2O_7 phase with relative density of 94%. It was observed that further doping of SrO (x = 0.2-0.4) leads to formation of Y_2Ti_2O_7 phase along with SrTiO_3 phase. Excessive SrO (x = 0.4) results in increase in ionic conductivity to 1.50 × 10~(-1) S cm~(-1) whereas it impedes the densification process with relative density of 85%.