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

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.