Photoluminescence due to efficient energy transfer from Ce3+ to Tb3+ and Mn2+ in Sr3Al10SiO20

Sr3Al10SiO20, doped with Ce3+, Tb3+, Eu2+, (Ce3+ + Tb3+), (Ce3+ + Mn2+), (Eu2+ + Tb3+) and (Eu2+ + Mn2+) are prepared by wet-chemical route and energy transfer from Ce3+ to Tb3+ or Mn2+ are investigated. The spectrum of Sr3Al10SiO20:Ce3+ shows single emission band at blue-violet region indicating the weak spin-orbit coupling of the ground state of Ce3+. Tb3+ doped Sr3Al10SiO20 yields both the blue emission 5D3-7FJ (J = 3, 4, 5, 6) and green emission 5D4-7FJ (J = 3, 4, 5, 6) of Tb3+. However, the relative intensity of 5D4-7FJ transitions increases with concentration due to cross-relaxation between two interacting Tb3+ centers. The green emission of Tb3+ is remarkably enhanced due to energy transfer from Ce3+ to Tb3+ when present together in Sr3Al10SiO20. The energy transfer phenomenon is also observed for Ce3+ and Mn2+ co-doped Sr3Al10SiO20 indicating that Ce3+ ion acts as a sensitizer in Sr3Al10SiO20 independent of the activator. Sr3Al10SiO20:Eu2+ shows broad emission band with the maximum in the blue-green region. However, Eu2+ does not act as a sensitizer of luminescence when co-doped with Tb3+ or Mn2+. This might be because of the existence of Eu2+ emission level at lower energy than the absorption energy level of Tb3+ as well as Mn2+ which does not allow the spectral overlap between the emission spectra of Eu2+ and the absorption spectra of Mn2+ or Tb3+ to induce sensitized luminescence.