Room temperature crystal structure of La1/3Zr2(PO4)3, a NASICON-type compound

The room-temperature crystal Structure of La1/3Zr2(PO4)(3), synthesized by the Pechim sol-gel process, has been determined from X-ray powder and neutron diffraction data [space group P3, Z = 6, a 8.7378(2) (A) over circle, c = 23.2156(7) (A) over circle]. It derives from the NASICON-structural type (space group R3c); if the [Zr-2(PO4)(3)](-) network is preserved, the two La3+ ions are found quasiordered along the c axis: 1 on the 1a (0, 0, 0), 0.82 on the 1b (0, 0, (1)/(2)) sites, and the remaining 0. 18 La3+ ions occupying partially a 2d site ((1)/(3), (2)/(3), 0.667(5)). One and two dimensional P-31 nuclear magnetic resonance (1D and 2D, respectively) investigations confirm this distribution.