ELECTRON-DENSITY IN YTIO2

Accurate electron density analyses have been performed on the title co mpound, yttrium titanate, at room and low temperature using W K alpha radiation. Room-and low-temperature Delta rho maps are generally consi stent. Difference electron densities near the two symmetrically indepe ndent O atoms differ markedly. These observations may have significanc e for understanding the role of the O atom in mediating d-electron int eractions between neighbouring Ti coordination polyhedra. Features hav ing lower symmetry than that of the approximately octahedral local env ironment are observed within the Ti coordination octahedron. Crystal d ata at room temperature: YTiO3, M-r = 184.79, T = 293K, Pnma, a = 5.69 01 (4), b = 7.6130 (7), c = 5.3381 (6) Angstrom, V = 231.24 (4) Angstr om(3), Z = 4, D-x = 5.308 Mg m(-3), mu(W K alpha) = 1.02 mm(-1), R = 0 .024, wR = 0.017, S = 1.64 (2) for 2996 independent reflections. Low t emperature: T = 127K, Pnma, a = 5.690 (4), b = 7.583 (6), c = 5.318 (5 ) Angstrom, V = 229.5 (3) Angstrom(3), D-x = 5.35 Mg m(-3), mu(W K alp ha) = 1.02 mm(-1), R = 0.021, wR = 0.015, S = 1.80 (2) for 2968 indepe ndent reflections.