Sol–gel synthesis of La0.5Sr0.5Ti0.5Cr0.5–x Fe x O3 perovskites: influence of Fe doping on structural and physical properties

Abstract

Polycrystalline powders of perovskites La0.5Sr0.5Ti0.5Cr0.5–x Fe x O3 (x = 0.0, 0.1, 0.2, 0.3, 0.4) were synthesized by the sol–gel method. X-ray analysis using the Rietveld refinements showed that samples crystallize in the orthorhombic structure with Pbnm (No. 62) space group. The lattice parameters and the unit cell volume increase with increasing Fe content. Magnetic measurements indicate that all our investigated samples exhibit an overall antiferromagnetic behavior mainly attributed to predominant Cr3+–O2−–Cr3+ and Fe3+–O2−–Fe3+ super-exchange interactions. The change in Weiss constant (Θ) is interpreted as interplay between super-exchange Cr3+–O2−–Cr3+ and Fe3+–O2−–Fe3+ and double-exchange Cr3+–O2−–Fe3+ interactions. All phases exhibit an insulating behavior which probably could be described by the adiabatic small polaron hoping model with increase in the polaron activation energy with increasing Fe content.