Structural, magnetic and electrical transport properties for a series of La1-xSrxFe1-xMnxO3 (0.3 ≤ x ≤ 0.7) compounds

The structural, electrical transport and magnetic properties have been studied for compounds: La1-xSrxFe1-xMnxO3 (0.3 <= v <= 0.7). The lattice parameter, a, first decreases with x, and followed by all increase when Sr2+ and Mn4+ was continuously doped. The cell parameters, b and c, slightly decrease with coupled substitution of Sr2+ for La3+ and Mn4+ for Fe3+. In the paramagnetic temperature range, formation of magnetic clusters is suggested; the sizes of clusters decrease with x up to 0.5, following that they increase sharply with continuing doping. The electrical behaviors of all specimens demonstrate insulators and the electrical resistivity increases with content of Mn4+ and Sr-2+ ions doped. A variable range hopping model is suitable to describe electrical transport process for the compounds at low temperature. At high temperature the electrical transport process call be described by bipolaron model for all compounds. (C) 2007 Elsevier B.V. All rights reserved.