Structure of the mixed oxides La0.6Pb0.4Mn1-yTiyO3 +/- z (0 < y < 0.4) viaRietveld refinements

The crystal structure of several compositions in the system La0.6Pb0.4Mn1-y TiyO3 (0 less than or equal to y < 0.4) have been investigated by powder X- ray diffraction using the Rietveld refinement technique. The solid solution s of compositions y = 0.1, 0.2, and 0.3 crystallize in the rhombohedral str ucture (space group R3c), while for the composition corresponding to y = 0. 4, the crystal structure transforms from rhombohedral to orthorhombic syste m (space group Imma). Profile refinements on all these compositions reveal that the MnO6 octahedra are distorted and rotated from their ideal position s. The doping at the B-site results in the formation of the orthorhombic ph ase Imma at room temperature. The structural implications on the magnetic p roperties also correlate with previous observations. (C) 2001 Elsevier Scie nce Ltd. All rights reserved.