Non-stoichiometry of Li2TiO3 under hydrogen atmosphere conditions

Li2TiO3 is one of the most promising candidate solid breeder materials. However, its structural properties have not been established, especially for a non-stoichiometric composition. In the present paper, non-stoichiometric compositions of Li2TiO3 have been extensively investigated by means of thermogravimetry, X-ray diffraction and color change observations. For the Li2TiO3 samples used in the present study, Li2CO3 and TiO2 powders were mixed in the proportion corresponding to the molecular ratio Li2O/TiO2 of either 1.00, 0.95, 0.938, 0.90 or 0.80. In thermogravimetry, mass of the Li2TiO3 samples was found to decrease with time in a hydrogen atmosphere, then to increase after the change of the atmosphere from hydrogen to oxygen. The color of the samples was observed to change from white to dark blue under a hydrogen atmosphere. These results suggest not only oxygen deficient but also Li2O deficient defect formation. Thus, the doubly non-stoichiometric composition, Li2-xTiO3-y, has been confirmed. (C) 2004 Elsevier B.V. All rights reserved.