Dion–Jacobson A′MiiiNaNb3O10 (A′ = Rb, Cs; M(iii) = Sm, Bi) and RbSmNa2Nb4O13 layered perovskites and their luminescent function

Abstract

Layered perovskites offer an ideal playground for researchers to tailor their multiple functions through cation and anion modifications; hence, research on them is vigorously pursued. The present study explored multivalent cationic combinations (Sm, Bi, and Na) in the two-dimensional perovskite blocks to realize novel three- and four-layered perovskite oxides belonging to the Dion–Jacobson series. The samples were synthesized by high-temperature solid-state reactions and extensively characterized. The successful structural refinements of the powder X-ray diffraction data by the Rietveld method and Raman spectral measurements confirmed the structural features. Rb analogues of the n = 3 and 4 members, RbM^IIINaNb₃O₁₀ (M(III) = Sm, Bi) and RbSmNa₂Nb₄O₁₃ exhibit tetragonal symmetry (S. G. P4/mmm). The Cs-based n = 3-member CsM^IIINaNb₃O₁₀ (M(III) = Sm, Bi) crystallizes in orthorhombic (S. G. Pnam) symmetry (a ∼ 30.50, b ∼ 7.70, c ∼ 7.80 Å), highlighting the effect of the bigger (Cs⁺) interlayer cations. The facile topochemical ion-exchange reactions of these phases, resulting in H⁺, Li⁺, Na⁺, K⁺, and [CuCl]⁺ exchanged analogs, have been demonstrated. The UV-visible diffuse reflectance data confirm the f–f electronic transitions of Sm³⁺ and oxygen to Bi³⁺ charge transfer transitions. The optical bandgaps of these oxides fall in the favorable range (∼3.2–3.5 eV) to explore various photocatalytic reactions. The emission in the red region became intense when it was promoted by the energy transfer from Sm³⁺ to Eu³⁺, as revealed by the photoluminescence measurements of Eu³⁺ doped RbSmNaNb₃O₁₀. In the Tb-doped RbSmNaNb₃O₁₀ sample, energy transfer from Tb³⁺ to Sm³⁺ was noticed. These observations were rationalized by an appropriate energy transfer mechanism, reinforcing the applicability of the compounds as potential phosphor materials.