Abstract
X-ray diffraction, magnetic, transport and SEM measurements were used to investigate the role of structural and magnetic inhomogeneities in the formation of magneto-transport properties of the La0.6−xSmxSr0.3Mn1.1O3−δ (x=0–0.6) ceramics. Reduction of the a parameter of perovskite structure and change of its symmetry are shown to be due to both replacement of La3+ by Sm3+ and an increase concentration of anion and cation vacancies. Broad asymmetric 55Mn NMR spectra are indicative of the high frequency electron double exchange Mn3+↔Mn4+ and demonstrate the heterogeneity of magnetic and valence Mn-states. An excess manganese is dissolved in perovskite structure statistically without formation of planar antiferromagnetic clusters of Mn2+ ions in the deformed A positions. Constructing phase diagram of “composition–structure–properties” describes a strong correlation between structural, resistive and magnetic properties as well as reflects a special role of structural defects in the formation of magneto-transport properties of the rare-earth manganites.
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