Structural, electrical, optical and magnetic properties of SmCrO3 chromites: Influence of Gd and Mn co-doping

Abstract

Impact of co-doping of Gadolinium (Gd) and Manganese (Mn) ions on the structural, electrical, optical and magnetic properties of SmCrO3 (SCO) orthochromite compound has been systematically investigated for the first time. The lattice volume expanded with only Mn substitution whereas it shrinks in the co-doped compounds. The tolerance factor decreased while the orthorhombic distortion was found to increase with co-doping. Tilt angle, θ[101] (ο) increased in the co-doped compounds. On the contrary, ∅[010] (ο) initially decreased and then increased. The increased orthorhombic distortion with co-doping also influenced the Raman modes. The electrical resistivity got enhanced in the co-doped samples and its behavior was explained based on Mott's variable range hopping model. Hopping energy and mean hopping distance have also been estimated for the co-doped compounds. The optical bandgap of pristine SCO compound was observed to vary with co-doping, signifying the potential applications of these compounds as photocatalyst. Two compensation temperatures (defined as a temperature where the magnetization changes polarity) were noticed in co-doped compounds. The magnetization reversal was observed in all the co-doped compounds under lower applied magnetic field. The low temperature magnetocaloric effect got enhanced significantly with increasing co-doping content implying the usefulness of these compounds as low temperature refrigerant materials.