Electrical Resistivity Behavior and VRH Transport Mechanism in Semiconducting LaSrMnFeCrO (0.10≤ x≤0.25) Manganites.

The transport properties and conduction mechanism in LaSrMnFeCrO (0≤ x≤0.3) have been investigated. The undoped samples show metal-semiconductor transition with a peak of resistivity at a temperature T, whereas for all doped compounds the semiconducting behavior persists in the whole temperature range. The insertion of Cr and Fe ions leads to the increase of resistivity because the simultaneous substitution of Fe and Cr for Mn reduces the number of available hopping sites for the Mn e electron and suppresses the double-exchange mechanism. It was found that the transport mechanism for substituted samples is dominated by the variable range hopping of small polarons between localized states in a model where the various parameters estimated from Mott's relation obey the variable range hopping (VRH) mechanism. [ABSTRACT FROM AUTHOR]