Influence of Al3+ on glass-forming ability, structural and electrical properties of the Na3.4Sc2Si0.4P2.6O12 superionic conductor

This work reports the microstructure, and structural and electrical properties of Na3.4AlxSc2-xSi0.4P2.6O12 (0.0 <= x <= 1.7) NASICON (Na+ Super-Ionic Conductor) compounds obtained from the crystallization of a precursor glass. The addition of aluminum in the Na3.4Sc2Si0.4P2.6O12 NASICON composition improves the glass-forming ability of the precursor glass, which is evaluated by thermal analysis. Moreover, the Al3+/Sc3+ isovalent substitution allows us to change the lattice parameters of the NASICON structure, without varying the number of charge carriers (Na+ ions) per unit formula. X-ray diffractograms reveal the formation of the Na3Sc2(PO4)(3) NASICON-type phase after crystallization of the parent glasses. From the structural characterization, it is also noted that the inclusion of Al3+ in the NASICON structure causes a volume contraction, which in turn, increases the activation energy and decreases the ionic conductivity. Thus, we demonstrated that the substitution of Sc3+ ions in the Na3Sc2(PO4)(3) NASICON-type structure by an ion of the same valence, but with a smaller atomic radius, decreases the ionic conductivity of the material. (C) 2020 Elsevier B.V. All rights reserved.

Automated summary

This study investigates the microstructure, thermal properties, and structural changes during crystallization of Na3.4AlxSc2-xSi0.4P2.6O12 NASICON compounds. It is found that adding aluminum in the NASICON structure improves glass-forming ability but decreases ionic conductivity.