Influence of K+ substitution on germanium doped strontium silicate (Sr3-3xK3xSi3-3yGe3yO9-δ; 0 ≤ x ≤ 0.20, y=0.1) for application as solid electrolyte.

The different alkali metal substitution strategies of the strontium meta -silicate based ion conductors have been enormously cross-examined to synthesize cost-effective novel electrolyte for Intermediate Temperature Solid Oxide Fuel Cells (IT-SOFCs). In the present investigation, crystal structure, phase formation, microstructure, total conductivity and stability of the Potassium and Germanium incorporated Sr 3 Si 3 O 9 based system, Sr 3-3x K 3x Si 3-3y Ge 3y O 9-δ (0 ≤ x ≤ 0.20, y = 0.1), is examined for their application as solid electrolyte for electrochemical devices such as ITSOFCs. These samples have been made via solid state reaction route. X-ray Rietveld refinement method was used for the structural investigation. Raman and FT-IR spectroscopy were performed to examine the phase formation and absorption of light by the bonds of vibrating molecules to provide molecular characteristics and vibrational modes of the molecules. The X-ray Photoelectron Spectroscopy study was used to validate the characteristic valence states of the constituting elements. Thermo-gravimetric analysis was performed to inspect the thermal stability and weight changes in the compounds during heating process. In the SEM and EDS mapping, an amorphous phase of K 2 Si 2 O 5 can be visualized which seems to segregate along grain boundaries and this amorphous complexion augmented with K+ dopant concentration. AC Electrical impedance spectroscopy studies suggest that the ionic conduction in Sr 3-3x K 3x Si 3-3y Ge 3y O 9-δ could be from the oxide ions along with mobility of K+ ions of the glassy phase. In this study, we also tried to get the optimal doping condition with compositions to minimize numerous concern of the system. [Display omitted] [ABSTRACT FROM AUTHOR]