Stoichiometry, structures and polymorphism of spinel-like phases, Li1.33xZn2-2xTi1+0.67xO4

A complete range of spinel-like solid solutions forms between Li4Ti5O12 and Zn2TiO4. Over a range of intermediate compositions, Li1.33xZn2-2xTi1+0.67xO4 (0.50 less than or equal to x less than or equal to 0.90), the solid solutions are primitive cubic, but for compositions to either side, they are face centred. Rietveld refinement of powder X-ray diffraction data shows that ordering of Li and Ti onto two sets of octahedral sites is responsible for the primitive structure; Li and Zn are disordered over the tetrahedral sites. A fully ordered, ideal composition occurs at x = 0.75, Li2ZnTi3O8, which is isostructural with LiFe5O8. The phase diagram of the spinel join shows that the ordered, primitive cubic solid solutions transform to disordered, face-centred cubic solid solutions at high temperatures, with a maximum in the transition temperature at 1150 degrees C for x = 0.75. The subsolidus phase diagram Li2TiO3-TiO2-ZnO at 1150 degrees C has been determined.