A SYNCHROTRON X-RAY STUDY OF THE ELECTRON-DENSITY IN SMFEO3

Structure factors for small, hydrothermally grown samarium orthoferrit e, SmFeO3, were measured with focused lambda = 0.7 Angstrom synchrotro n radiation. Approximate high symmetry in the Delta rho images indicat es that cations deform the electron density far more strongly than the O atoms. The most obvious effect is on distribution of the Fe atoms. The influence of the nearest low-symmetry (C-s) O coordination on the electron density of the Sm cation is weak by comparison with that of t he Sm-Fe interactions, as is illustrated by the high symmetry of the d p map near the Sm atom. The Sm-Fe interactions appear to affect the ma gnetic ordering and spin configuration of the Fe atoms. Space group Pn ma, orthorhombic, M(r) = 254.20, a = 5.6001 (3), b = 7.7060 (7), c = 5 .3995 (6) Angstrom, V = 233.01 (4) Angstrom(3), Z = 4, D-x = 7.246 Mg m(-3), mu(0.7) 28.5 mm(-1), F(000)= 448, T = 293 K, R = 0.017, wR = 0. 021, S = 3.83 (8) for 1329 unique reflections.