STRUCTURAL AND MICROSTRUCTURAL STUDIES OF THE SERIES LA2 3-XLI3X-SQUARE-1/3-2XTIO3/

Much work has been done on the series La(2/3-x)Li(3x)square(1/3-2x)TiO (3) because of the high level of Li+ ionic conductivity exhibited by t his material. Curiously, the structural aspect was not yet really expl ored. We propose here a structural model for the series, in the compos ition range 0.06 < x < 0.14, on the basis of X-ray powder diffraction and transmission electronic microscopy data: the symmetry is tetragona l (P4/mmm), and the unit cell derives from that of the perovskite ABO( 3) (a = a(p), c similar to 2a(p)). Vacancies, La, and Li ions are uneq ually distributed on two sites, 1a and 1b; the La distribution is appr oached by the Rietveld method from the X-ray powder patterns and confi rmed by simulation of high resolution electron microscopy images. (C) 1996 Academic Press.