Effect of potassium substitution at Sr-site on the structural, morphological and electrical properties in Sr3 − 3x K3x Si3O9 (0.0 ≤ x ≤ 0.2) trimer strontium meta-silicate

Solid electrolytes are the principal component of solid oxide fuel cells (SOFCs) and play a vital role in controlling the conduction mechanism. We have prepared multiple compositions of Sr3 − 3xK3xSi3O9 (0.0 ≤ x ≤ 0.2) via solid-state reaction route for the possible application as solid electrolyte for SOFCs. We have studied the phase formation and phase evolution via XRD, Raman and FTIR; morphological transformation via SEM and EDX and the ion-conducting behaviour of the system via conductivity measurements with varying the potassium concentration. Band gap of the investigated compositions was determined via the Tauc plot of UV-Vis measurement. A correlation between the dopant concentration, phase formation and conductivity has been established to explain the conductivity behaviour. The results indicate that high K concentration is helpful in achieving the required transport behaviour as required for IT-SOFC electrolytes.