Structural, luminescence and EPR studies on SrSnO3nanorods doped with europium ions

Abstract

The present study describes the structural and luminescent properties of SrSnO₃ nanorods containing Eu³⁺ ions. Based on Rietveld refinement of XRD patterns corresponding to both undoped and europium doped SrSnO₃ nanorods, it is inferred that the average bond lengths of Sr–O1 linkages, which have a square planar geometry around Sr²⁺ in the SrO₁₂ polyhedra present in SrSnO₃, remained unaffected with Eu³⁺ incorporation into the lattice. However, the average bond lengths of shorter Sr–O2 linkages increase and longer Sr–O2 linkages decrease with Eu³⁺ doping into the SrSnO₃ lattice. A lack of variation in the lattice parameters of SrSnO₃ with doped Eu³⁺ ions is explained based on mutually compensating changes in the average bond lengths of the Sr–O2 linkages in the unit cell. Luminescence studies have confirmed that Eu³⁺ ions occupy the centrosymmetric Sr²⁺ site only up to 2 at%, beyond which Eu³⁺ ions exist in a significantly distorted environment (grain boundaries). Beyond 3%, incorporation of Eu³⁺ ions into the SrSnO₃ lattice leads to the formation of a Eu₂Sn₂O₇ phase. From the EPR studies it is confirmed that around 5% of the incorporated Eu³⁺ ions get converted to Eu²⁺ ions and they occupy Sr²⁺ sites in the lattice.