JOURNAL OF SOLID STATE CHEMISTRY 96, 446-450 (1992) Preparation of LiTi204 Single Crystals with the Spinel Structure J. AKIMOTO, Y. GOTOH, K. KAWAGUCHI, AND Y. OOSAWA National Chemical Laboratory for Industry, Tsukuba, lbaraki 305, Japan Received July 1, 1991; in revised form September 13, 1991 Single crystals of the spinel-type LiTi:O 4(Cubic, Fd3m, a = 8.4095(12) A) have been prepared by the reaction of lithium metal and TiO2 at 1373 K in a sealed iron vessel. The structure refinement by a single crystal X-ray diffraction study confirmeda normal spinel cation distribution; the lithium cations are located at the tetrahedral 8a sites, the titanium cations occupy the octahedral 16d sites, and the oxygen parameter u = 0.2622(4) with the final R = 3.8% (R, = 2.7%) for 60 independent observed reflections. The octahedral Ti-O distance is 2.005(3) A, and the tetrahedral Li-O distance is 1.999(3) A. The superconductivity for the crystals was observed by the magnetization measurements. 1992 Academic Press, Inc. Introduction The spinel-type LiTi204 is known to be a superconductor with a transition tempera- ture Tc = 11 K (1). This compound was originally synthesized and structurally char- acterized by Deschanvres et al. (2) as an end-member in the solid solution system Li 1 +xTi2_xO4 (0 =< x =< ~). The solid solution system LiMxTi 2 xO4 (M = Li +, Mn 2+, Mg z+, Cr 3+, AI 3+) was also investigated with regard to the compositional depen- dence of the lattice parameters and physical properties such as the normal superconduct- ing or metallic-semiconducting transition (3-6). In all the experimental studies re- ported to date, sintered powder samples were used, although single crystals were needed in order to investigate the more pre- cise structural and electronic properties. Recently, single crystals of the reduced alkaline titanates (e.g., NaTi20 4 (7), NaTisO13 (8), Na0 25TIO 2 (9), and hollandite- 0022-4596/92 $3.00 Copyright 1992 by Academic Press, Inc. All rights of reproduction in any form reserved. type KxTiO2 (10) and CsxTiO2 (11)) were prepared by the reactions of alkaline metals (Na, K, Cs) and titanium oxides using sealed Fe or Ni vessels at high temperatures. We have applied this preparation method to the Li-Ti-O system and have succeeded in the preparation of the stoichiometric LiTi20 4 single crystals. In this paper, we report the preparation and crystal structure of LiTi204 single crystals. Experimental and Results Preparation of the Crystal Starting materials were TiQ powder (99.9%), which was composed of rutile and anatase and was dried at 673 K, and lithium metal blocks with 99% purity. They were placed in a sealed iron vessel with an atomic ratio of Li/Ti = 1/2, heated in a resistance furnace at 1373 K in an argon gas flow for 10 hr, and slowly cooled to room tempera- 446