Double NASICON-type cell: ordered Nd3+ distribution in Li0.2Nd0.8/3Zr2(PO4)3.

The NASICON compound Li(0.2)Nd(0.8/3)Zr(2)(PO(4))(3), synthesized by a sol-gel process, has been structurally characterized by TEM and powder diffraction (neutron and X-ray). It crystallizes in the space group R3[combining macron] (No. 148): at room temperature, the Nd(3+) ions present an ordered distribution in the Zr(2)(PO(4))(3) network which leads to a doubling of the classical c parameter (a = 8.7160(3) A, c = 46.105(1) A). Above 600 degrees C, Nd(3+) diffusion occurs leading at 1000 degrees C to the loss of the supercell. This reversible cationic diffusion in a preserved 3D Zr(2)(PO(4))(3) network is followed through thermal X-ray diffraction. Ionic conductivity measurements have been undertaken by impedance spectroscopy, while some results concerning the sintering of the NASICON compound are given.