A REDUCED NEODYMIUM TITANATE WITH A NEW INTERGROWTH STRUCTURE TYPE

Single crystals of a new reduced neodymium titanate, Nd3Ti4O12, have been obtained by slow cooling of a reduced Nd-Ti-O ceramic precursor in a molten neodymium borate flux under high vacuum. Single crystal X-ray diffraction (space group Pcmn, a = 5.420(1) Å, b = 7.610(1) Å, c = 22.015(5) Å, Z = 4, Pearson symbol oP76) showed that the structure of Nd3Ti4O12 is built from an arrangement of corner-sharing and edge-sharing TiO6-octahedra that can be considered as a regular intergrowth of the GdFeO3 and CaTa2O6 structure types. The material is nonmetallic (R(25°C) = 35 Ωcm) which may arise due to the localization of the Ti 3d-electrons in the edge-sharing pairs of TiO6-octahedra (short Ti-Ti distance of 2,760(3) Å). © 1993 Academic Press, Inc.