Proceedings of the NMR USERS MEETING
PROCEEDINGS OF THE 18ᵗʰ NMR USERS MEETING

The design of Na-ion all-solid-state batteries requires the optimization of materials to be used as solid electrolytes. Fast ion-conducting glass-ceramics are suitable for this purpose since they present the features of both glass phase and fast ion-conducting crystallites[1]. Glass-ceramics based on superionic crystalline structure Na5RESi4O12 (N5, RE = Sc, Y) can be produced by controlled crystallization of sodium silicate glasses with specific compositions [2] and can reach ionic conductivities up to 0.1 S/cm [3]. Their compositions and properties can be isostructurally modified by Si –> P substitution. Precursor glasses of compositions Na3.9RE0.6P0.3Si2.7O9 (NREPS) and Na4.2RE0.6Si3O9 (NRES), (RE = Sc, Y), were synthesized by the melting-quenching technique, and glass-ceramics were prepared according to the crystallization temperatures found by DSC. X-ray diffraction pattern of the glass-ceramics showed that the N5 crystal structure was found for NScS and NScPS glass-ceramics annealed at 905 and 925 °C, respectively. Multinuclear (29Si, 23Na, 31P and 45Sc) MAS NMR was used to monitor the conversion of the glassy precursor phase into the multi-phase glass ceramics at different stages of thermal annealing, confirming the successful substitution of (SiO4)4- by (PO4)3- ions in the N5 structure. Impedance spectroscopy and static 23Na experiments were used to investigate ion dynamics of glass-ceramics containing the N5 structure.