Structural implications on transport dynamics in K-doped monomeric SrSiO3 system

Abstract

Excellent ionic conductivity of alkali metal doped strontium meta silicate solid electrolytes has widely made consideration to their usage in electrochemical devices e.g. solid oxide fuel cells (SOFCs). The present study aimed to explore the conductivity enhancement in the potassium (K) doped monomeric SrSiO3 solid electrolyte with its structural changes by variation of dopant concentration. A series of different K-doped monomeric system SrSiO3 (i.e. Sr1-xKxSiO3) were synthesized with varying K concentration (in %) as x = 0, 10, 15, 20, 25, 30. The structural, optical and transport properties were investigated via XRD, BET, SEM, FTIR, Raman and Impedance spectroscopy techniques. The investigations confirm the co-existence of crystalline phase along with amorphous phases and strengthened by visualizing SEM micrographs which was further correlated with the Raman and FTIR results. The thermal stability measurement of the prepared samples conducted through TGA analysis led to the inference that introduction of K in this system results in generation of K-rich glassy phases. The above deduction was strengthened by impedance measurements showing highest conductivity of 0.38 × 10−3 S-cm−1, at 873 K in air for Sr0.7K0.3SiO3, among all synthesized samples. Furthermore, un-doped strontium silicate showed presence of more than one phase apart from monoclinic phase and behave as nonconducting phase material in the deliberated temperature range (473 K – 973 K). Changes in crystallinity or the formation of secondary phases can impact transport dynamics through altered grain boundaries, defect concentrations, and diffusion pathways. © 2024 Elsevier B.V.