A Titanium and Tantalum Phosphate LiNaTiTa2P2O13 with An Open Framework hosting Li and Na Ions

Abstract

Herein, we report a detailed structural, electric, thermal and optical analysis of a titanium and tantalum phosphate LiNaTiTa 2 P 2 O 13 . The title compound is comprised of typical ReO 3 -type layers constituted by corner-sharing TiO 6 and TaO 6 octahedra, bridged by PO 4 tetrahedra, which is closely related to monophosphate niobium bronzes. The existence of pentagonal tunnels, hosting the Li + and Na + ions, endow LiNaTiTa 2 P 2 O 13 a moderate ion transportation behavior (4.67×10 -4 S/cm at 823 K). In addition, the successful substitution of Nb for Ta in LiNaTiTa 2 P 2 O 13 results in the optical absorption red-shift towards visible range with a narrowing band gap, which may provide a route of isomorphic replacement to band engineering for photo-catalysis.