Microstructure and upconversion luminescence of Yb3+ and Ho3+ co-doped BST thick films

Ba0.8Sr0.2TiO3 (BST) thick films co-doped with Yb3+ and Ho3+ were fabricated by the screen printing techniques on alumina substrates. The structure and morphology of the BST thick films were studied by XRD and SEM, respectively. After sintered at 1240 °C for 100 min the BST thick films are polycrystalline with a perovskite structure. The upconversion luminescence properties of the RE-doped BST thick films under 800 nm excitation at room temperature were investigated. The upconversion emission bands centered at 470 and 534 nm corresponding to 5F1 → 5I8 and 5F4 → 5I8 transition, respectively were observed, and the upconversion mechanisms were discussed. The dependence of the upconversion emission intensity upon the Ho3+ ions concentration was also examined; the emission intensity reaches a maximum value in the sample with 2 mol% Yb3+ and 0.250 mol% Ho3+ ions. All the results show that the BST thick films co-doped with Yb3+ and Ho3+ may have potential use for photoelectric devices.