REMARKS ON THE BINARY SYSTEMS Li//2O-Me//2O//5 (Me equals Nb,Ta).

Article abstract of DOI:10.1016/0025-5408(87)90230-3

In the Li//2O-Ta//2O//5 system there are two new defective phases: Li//3//. //5TaO//4//. //2//5 and Li//1//6Ta//4O//1//8, with anionic vacancies. At 700 degree C these phases are characterized by disordered distribution of Li** plus and Ta**5** plus ions, like Li//3TaO//4 itself. At temperatures higher than 700 degree C a gradual cation ordering occurs, and the x-ray powder diffraction patterns show progressively increasing superstructure reflections similar to the ordering process of cations in Li//3TaO//4. In the examined temperature range (700-1000 degree C) the equilibrium series Li//3TaO//4-Li//3//. //5TaO//4//. //2//5-Li//1//6Ta//4O//1//8-Li//7TaO//6-Li//2O was assessed. In the system Li//2O-Nb//2O//5, an analogous series only for T greater than equivalent to 900 degree C was verified.