GROWTH AND STRUCTURE-ANALYSIS OF NONSTOICHIOMETRIC SINGLE-CRYSTAL NAXTIO2 (X INFINITY 0.5) WITH THE ALPHA-NAFEO2-TYPE STRUCTURE

Single crystals ofNaxTiO2 (x ∼ 0.5)with the rhombohedral α-NaFeO2-type structure were successfully prepared from high-temperature solutions of sodium metal and titanium dioxide. The structure refinement by a single crystal X-ray diffraction study confirmed a triangular lattice outstanding two-dimensionality of Na0.54TiO2 and the space groupR-3mwith the finalR = 5.7% (Rw = 5.1%)for 170 independent observed reflections. The lattice parameters of the present Na0.54TiO2 crystal area = 2.9791(6)Å,c = 16.928(3)Å, andV = 130.11(5)Å3. These crystals are strongly attacked by air atmosphere, and a remarkable lattice contraction toward thec-axis direction in the trigonal lattice was observed when the Na contents were decreased. The most highly contracted lattice constants for the compound with the chemical formula Na0.3TiO2 area = 2.9665(5)Å,c = 15.755(9)Å, andV = 120.07(8)Å3. © 1990 Academic Press, Inc. All rights reserved.