Structural, optical and magnetic properties of Sm3+ doped yttrium orthoferrite (YFeO3) obtained by sol-gel synthesis route.

Fine powders of Y1-x Sm x FeO3 (x  =  0, 0.05, 0.10, 0.15) were synthesized via citrate based sol-gel route. While the as synthesized powders were amorphous, the calcined (900 °C/8 h) powders were confirmed to be polycrystalline by x-ray powder diffraction (XRD) studies. The calcined powders were found to crystallize in an orthorhombic structure associated with the lattice parameters a  =  5.59 Å, b  =  7.60 Å, c  =  5.28 Å. These lattice parameters increased with the increase in Sm3+ content at yttrium sites. The strain that was obtained by the Williamson-Hall method increased with the increase in dopant (Sm3+) concentration vis-à-vis a decrease in crystallite size. Diffuse reflectance spectroscopic studies suggest an increase in band gap as Sm doping level increased. Significant enhancement in magnetization associated with a decrease in coercive field accompanied by a transition from anti-ferromagnetic to soft ferromagnetic behaviour in Sm doped YFeO3 were encountered. It is hoped that these materials with the enhanced magnetic properties could be of potential use for multifarious applications.