Ab-initio investigation of a short range order and ionic conductivity in the La-Li-TiO/sub 3/ system

We have used ab-initio FLAPW method for the investigation of atomic and electronic structure of La/sub 0.5/Li/sub 0.5/TiO/sub 3/ compound. We have carried out the set of total energy calculations with different Li atom location. It was determined that in this compound, a tetragonal crystal structure in which La atoms are alternated with Li atoms is energetically efficient. It is shown that a total energy minimum has been reached when Li atoms are centered on the faces of the cube formed by Ti atoms. We have derived a new formula describing lanthanum-lithium ionic conductors: La/sub (2/3-x)/Li/sub 3x//spl square//sub 3(1-x)/TiO/sub 3/. Dependence of the number of lithium vacancies on La and Li concentration for different ordering of these atoms was determined. We have determined possible Li atoms diffusion ways, and calculated the energy barriers too.