La0.67Sr0.33Mn1−xTixO3 (0≤x≤0.20) polycrystalline materials are prepared by employing lower annealing temperature compared to the temperatures reported for the materials of the same composition. The transport and magnetic properties of these materials are significantly different from those compounds prepared at higher annealing temperature. Samples with x<0.10 show metal–insulator transition and those with x≥0.10 exhibit insulating behavior over the entire temperature range investigated. A gradual transition occurs from the ferromagnetic-metallic state to the ferromagnetic-insulator state with increasing Ti substitution. Lattice parameters and bond lengths of Mn and its near neighbors however do not change appreciably with the dopant content x in these materials. It is shown that Ti4+ doping in the low-temperature annealed samples is inhomogeneous, resulting in isolated Mn rich regions that are connected by a variable range hopping polaron.

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Sm 0.5−x Pr x Sr 0.5 MnO 3 exhibits variety of ground states as x is varied from 0 to 0.5. At an intermediate doping of x = 0.3 a charge-ordered CE type antiferromagnetic insulating (AFI) ground state is seen. The transition to this ground state is from a paramagnetic insulating (PMI) phase through a ferromagnetic metallic phase (FMM). Local structures in PMI and AFI phases of x = 0.3 sample have been investigated using Pr K-edge and Sm K-edge Extended X-ray Absorption Fine Structure (EXAFS). It can be seen that the tilting and rotation of the MnO 6 octahedra about the b-axis are responsible for the charge ordered CE-type antiferromagnetic ground state at low temperatures. In addition a shift in the position of the rare earth ion along the c-axis has to be considered to account for observed distribution of bond distances around the rare earth ion.