A comparative study of structural, magnetic and catalytic properties of half doped nanocrystalline La0.5A0.5Mn0.5Fe0.5O3 (A = Ca, Sr) perovskite oxides: Highly efficient and versatile candidates for enhanced oxidative degradation of hazardous organic dyes at ambient conditions

Abstract

This work presents a systematic study of half doped nanocrystalline La0.5A0.5Mn0.5Fe0.5O3 (A = Ca, Sr) perovskite oxides to examine the effect of A-site cation radius on structural, magnetic and catalytic properties via different characterization techniques. Rietveld refinements of powder X-ray diffraction data confirmed the orthorhombic symmetry for both the samples with Pbnm space group. The results show an increase in lattice parameters and unit cell volume with doping of larger A cation. The BET surface area for Ca and Sr-doped samples has been found to be 32.3 m2/g and 33.8 m2/g respectively. The magnetic properties of nano structured samples show magnetic inhomogeneity due to coexistence of ferromagnetic and antiferromagnetic interactions. The magnetization has enhanced in Sr-doped sample which may be associated with increase in double exchange interactions between mixed valence manganese ions through oxygen. Moreover, the synthesized nano samples have been employed to catalytic degradation of rhodamine B dye as model pollutant under normal atmospheric conditions and it has been found that Sr-doped sample has shown better catalytic dye degradation than Ca-doped (99% degradation in 25 min) due to the presence of greater number of Mn3+/Mn4+ redox couples as determined by iodometric titration. Additionally, methylene blue and methyl orange dyes were also tested for catalytic degradation by more active Sr-doped catalyst in order to check its versability.