Crossrelaxations and non-radiative energy transfer from (⁴G_5/2) Sm³⁺ → (⁵D₀) Eu³⁺: B₂O₃–ZnO glasses

Graphical abstract: The energy transfer process occurring from Sm³⁺ to Eu³⁺ in B₂O₃–ZnO (BZn) glasses is analyzed. Based on the Foster–Dexter theory, the possibility of energy transfer between Sm³⁺ and Eu³⁺ has been demonstrated from the spectral overlap of Eu³⁺ absorption and Sm³⁺ emission, photoluminescence spectra, energy level diagram and lifetime measurements. The energy transfer mechanism in (Sm³⁺ + Eu³⁺) co-doped glass is governed by dipole–dipole interaction. - Highlights: • Spectroscopic properties of individually doped Sm³⁺, Eu³⁺ & co-doped (Sm³⁺ + Eu³⁺) in BZn glasses were studied separately. • The effect of Eu³⁺ concentration on luminescence properties is explained from cross-relaxations. • Energy transfer from Sm³⁺ (⁴G_5/2) to Eu³⁺ (⁵D₀) has been explained from Foster–Dexter theory. • Dipole–dipole mechanism governs the energy transfer from Sm³⁺ to Eu³⁺. - Abstract: The present paper reports on the results concerning to photoluminescence features of Eu³⁺, Sm³⁺ ions and energy transfer process occurring from Sm³⁺ to Eu³⁺ doped in 45 B₂O₃–55 ZnO (BZn) glasses prepared by melt quenching technique. Luminescence quenching as a function of Eu³⁺ concentration in BZn glasses has been discussed. Among the studied concentrations, 0.5 mol% of Eu³⁺ is optimized because it has exhibited red emission transition ⁵D₀ → ⁷F₂. With regard to Sm³⁺ glasses, orange emission at 602 nm (⁴G_5/2 → ⁶H_7/2) has been noticed on exciting with λ_exci = 403 nm. Based on the Foster–Dexter theory, the possibility of energy transfer between Sm³⁺ and Eu³⁺ has been explained from the spectral overlap of Eu³⁺ absorption and Sm³⁺ emission. The optimized concentration 0.5 mol% of Eu³⁺ is co-doped with Sm³⁺ in various concentrations ranging from 0.1 to 1.5 mol% inorder to study the sensitization effect of Sm³⁺ on Eu³⁺ luminescence. The results have revealed that with the addition of Sm³⁺ to Eu³⁺: BZn glass, emission intensity of Eu³⁺ has been enhanced due to migration of Sm³⁺ excitation energy. Energy transfer based enhanced emission in the co-doped (Sm³⁺ + Eu³⁺): BZn glasses have been discussed accordingly from photoluminescence spectra, energy level diagram and lifetime measurements, colour coordinates and also the mechanism governing the energy transfer process has been explained in detailed. Colour coordinates for the co-doped glasses upon exciting at 403 nm were also analysed. The results suggest that, the studied combination of rare earth ions could be promising candidates for red colour emitting LEDs in solid state lightning