THE STRUCTURE OF NA5TI(PO4)3

The sodium titanium phosphate Na5Ti(PO4)3 crystallizes in the trigonal space group R32 (a = 9.0607(2) Å, c = 21.734(1) Å, V = 1545.3 Å3, dm = 2.84(2), dc = 2.89 Mg · m-3, Z = 6). R = 0.022 and Rw = 0.023 for 831 reflections. The structure belongs to the Nasicon-type family and is characterized by a 2-2 titanium-sodium ordering along the c axis. The four crystallographically independent sodium atoms show coordination numbers 6 and 8. The cell parameters and the cationic distribution are consistent with the rules governing the structural evolution of such types of material. © 1993 Academic Press, Inc.