Phase stabilization and effect of trivalent lanthanide substitution on Dy2FeMnO6 double perovskite compounds

Abstract

Double perovskites exhibit interesting properties due to the presence of different B and B′ cations in their crystal lattice. The phase stabilization of Dy2FeMnO6 double perovskite compound is carried out using conventional solid-state reaction technique. Additionally, the effect of La3+ ion substitution on the physical properties of Dy2FeMnO6compound has been studied. The Rietveld refinement of powder X-ray diffraction patterns have been initiated with the structural model of DyFeO3orthoferrite and found with excellent goodness of fit for the orthorhombic symmetry with Pbnm space group. Hence, it is confirmed that the substituted Mn–ion has stabilized into double perovskite Dy2FeMnO6 crystal structure. The La-substituted samples exhibit marginal increase in lattice cell parameters and volume of the unit cell due to the substitution of larger ionic radii La3+ion while comparing with Dy3+ ion. The X-ray photoelectron measurements reveals the existence of Dy, La, Mn and Fe ions in +3 oxidation state and reveals the stable double perovskite structure. The La-substituted samples show no major variation in morphology while comparing with parent Dy2FeMnO6 compound. Raman spectral analysis indicates the presence of Dy2FeMnO6 phase, which are indicated by the deviation from DyFeO3 orthoferrite phase. The substitution of La ions into the Dy2FeMnO6 double perovskite structure is also evident from the Raman analysis. There is no more major influence on band gap values of La-substituted samples while comparing with pure Dy2FeMnO6sample has been obtained from the diffused reflectance studies. The photoluminescence studies indicate that the samples can be excited by the blue and ultra-violet light radiation. The magnetization analysis reveals that the Dy2FeMnO6 sample exhibits antiferromagnetic ordering due to the presence of Fe, Mn and Dy ions in the lattice. It is also identified that the substitution of La3+ ion disturbs the locked-in spins in Dy2FeMnO6 system to exhibit better magnetic behaviour in the presence of an external magnetic field.