Ionic Conductivity of the NASICON-Related Thiophosphate Na1+x Ti2-x Gax (PS4 )3

Chemistry. 2019 Mar 15;25(16):4143-4148. doi: 10.1002/chem.201805569. Epub 2019 Feb 18.

Abstract

Inspired by the recent interest in fast ionic conducting solids for electrolytes, the ionic conductivity of a novel ionic conductor Na1+x Ti2-x Gax (PS4 )3 has been investigated. Using X-ray diffraction and impedance spectroscopy the sodium ionic conductivity in this compound was demonstrated, in which bond valence sum analysis suggests a tunnel diffusion for Na+ . Substitution with Ga3+ leads to an increasing Na+ content, an expansion of the lattice and an increasing conductivity with increasing x in Na1+x Ti2-x Gax (PS4 )3 . Given the relation to the NASICON family, upon replacement of the phosphate by a thiophosphate group, a rich structural chemistry can be expected in this class of materials. This work demonstrates the potential for making NaTi2 (PS4 )3 an ideal system to study structure-property relationships in ionic conductors.

Keywords: NTPS; Thio-NASICON; ionic conductors; sodium thiophosphate.