Polymorph co-existence and its implication on transport dynamics in monomer and trimer strontium meta-silicate

Abstract

Alkali metal doped strontium meta-silicate, a highly conductive system, is being studied as an alternative to solid electrolyte for Solid Oxide Fuel Cells (SOFCs). Its high electrical conductivity is attributed to its structure and dopant strategies. Based on the recent reports, it was observed that it can exist in multiple forms depending upon synthesis route and conditions. The present study deals with the analysis of polymorphism inside strontium meta-silicate (SrSiO3)X using two different configurations viz. monomer (M) corresponding to X = 1 and Trimer (T) corresponding to X = 3, and without any dopant, to ruled out any secondary glassy phase inside the parent compound. The structural analysis showed that for the samples prepared via solid state reaction (SSR) route, the compound contains multiple phases simultaneously irrespective of the temperature and configuration. The present work showed the co-existence and stability of three phases of meta-silicate synthesised via SSR even at high temperatures. The co-existence of multiple phases has led to the enhancement of conductivity by two orders of magnitude in intermediate temperature range of operation for SOFCs. © 2020 Elsevier Ltd