LiTa2PO8: a fast lithium-ion conductor with new framework structure

A new lithium-ion conducting oxide, LiTa2PO8, with a three-dimensional (3D) framework structure was synthesized. The complementary use of synchrotron XRD and neutron diffraction revealed that LiTa2PO8 crystallized into a monoclinic system (space group C2/c) with lattice parameters a approximate to 9.716 angstrom, b approximate to 11.536 angstrom, c approximate to 10.697 angstrom, and = 90.04 degrees. In this structure, the TaO6 octahedra and PO4 tetrahedra are connected via corner-sharing to form an unprecedented anionic framework, [(TaO6/2)(2)(PO4/2)](-), providing a 3D pathway for lithium-ion conduction. The sintered LiTa2PO8 pellets exhibited excellent lithium-ion conductivities: bulk conductivity of 1.6 x 10(-3) S cm(-1) and total conductivity of 2.5 x 10(-4) S cm(-1) at 25 degrees C.