Structural Magnetic and Electrical Properties in Nd-Doped Manganites (La0.70−xNdx)Sr0.30Mn0.70Ti0.30O3 with 0 ≤ x ≤ 0.30

The structural, magnetic and electrical properties of (La0.70−xNdx)Sr0.30Mn0.70Ti0.30O3 perovskites (0 ≤ x ≤ 0.30) prepared by the usual ceramic procedure were investigated. Structural Rietveld refinements of the X-ray powder diffraction revealed that for x = 0 the compound crystallizes in a rhombohedral (R\(\bar {{3}}\)c) perovskite structure, while for x = 0.10, 0.20 and 0.30 the structure becomes orthorhombic (Pbnm). The field-cooled, zero-field-cooled and M(H) measurements lead to conclude that the samples with x≥0.10 behave like spin-glass systems. The temperature dependence of the resistivity exhibits two transitions at two temperatures Tp1 and Tp2, with the same width for the two peaks. TP1 results from the competition between double-exchange and super-exchange mechanisms inside the grain (intrinsic effects) whereas TP2 arises due to the grain boundary effects (extrinsic effect). The resistivity of this system seems to be related to the competition between antiferromagnetic insulating (AFI) phases, ferromagnetic insulating (FMI) phases and ferromagnetic metal (FMM) phases, which is induced by Nd doping effect.