Mat. Res. Bull., Vol. 15, pp. 1655-1660, 1980. Printed in the USA. 0025-5408/80/111655-06502.00/0 Copyright (c) 1980 Pergamon Press Ltd. PHASE EQUILIBRIA IN THE SYSTEMLi20-TiO2 Georgina Izquierdo and Anthony R. West University of Aberdeen, Department of Chemistry, Meston Walk, Old Aberdeen, AB9 2UE, Scotland (Received September 22, 1980; Communicated by J. B. Goodenough) ABSTRACT The system Li20-Ti02 contains four stable phases: Li~TiO~, Li2Ti03, Li~Tis012 and Li2TisO~, and one metastable phase, H. Li2Ti03 under- goes an order-disorder phase transition at 1215°C. High Li2TiO3 forms an extensive range of solid solution between~44 and 66 mole % Ti02 and low Li~TiOs forms a more limited range of solid solution between ~47 and 51% Ti02. The temperature of the order-disorder transition decreases to either side of the Li2TiOs composition. The spinel phase Li~TisO~2, has an upper limit of stability at lOIS ± 5°C, above which it decomposes to high Li2TiOs ss and Li2Ti30~. Li2TisO~ has a lower limit of stability at 957 ± 2O°C, below which it decomposes to Li~TisO~2 and r u t i l e . During this decomposition of Li2Ti30~, phase H, a meta- stable phase of unknown composition, forms as an intermediate. Li2Ti~07 for@ns a short range of solid solutions between ~74 and 76% TiO2. A phase diagram for the system Li2O-Ti02 has been constructed using a combination of results determined here and those reported by GICQUEL, MAYERand BOUAZlZ. X-ray powder diffraction data are given for Li2Tis07, Li~TisO~2 and phase H. Introduction Several studies on the system Li2O-TiO2 have been made and there is general agreement on the occurrence of four compounds with formulae, Li~TiO~, Li2Ti03, Li~Tis012 and Li2Ti30~. The occurrence of two polymorphs of Li2TiOs is well-established (l - 7). The ordered poly- morph with a rock salt superstructure is the stable form. A meta- stable, cubic, disordered polymorph can be prepared under certain conditions (1) and is stable above the order-disorder transition temperature, 1213°C (7). Li2TiO3melts congruently at 1547°C (6). Li~TiO~ is an unusual compound in that it contains tetrahedrally coordinated Ti ~+ ions (8). It is dimorphic; the polymorph stable 1655