Electrical conductivity and complex impedance analysis of La0.7−xNdxSr0.3Mn0.7Ti0.3O3 (x≤0.30) perovskite

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¯3c) perovskite
structure, while for x = 0.10, 0.20 and 0.30 the structure
becomes orthorhombic (Pbnm). The field-cooled, zerofield-
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.