NMR investigations unveil phase composition-property correlations in SrNaSiO fast ion conductor.

This paper reports results of Na and Si solid-state NMR investigations carried out on sodium strontium silicate ion conductor, SrNaSiO and presents the first experimental evidence to show that different synthesis conditions induce multiple devitrified phases. Along with 1-dimensional NMR, Na MQMAS spectra have been used to identify the phases corresponding to polymorphs of NaSiO, in addition to the crystalline SrSiO and the glass/amorphous NaSiO phases. The surprising observation of about an order of magnitude higher ionic conductivity achieved in devitrified samples is attributed to the growth of the crystalline δ-NaSiO phase within the amorphous NaSiO phase domains, identified using NMR.