Influence of Si/P ordering on Na+ transport in NASICONs

The influence of Si/P ordering on Na+ transport in the high conducting NASICON composition, Na3Zr2Si2PO12, is investigated using molecular dynamics simulation. The study demonstrates that the Na+ conductivity in the system changes by more than an order of magnitude depending on the Si/P order in the structure. This rather surprising observation is attributed to the modulations in the electrostatic potential energy landscape along the conduction channel originating out of the increased coulombic repulsion of Na+ with P5+ ions compared to Si4+. The study reveals the significance of the order of framework cations in fast ion transport in solids with aliovalent substitutions.