Preparation, patterning and luminescent properties of oxyapatite La9.33(SiO6)4O2:A(A = Eu3+, Tb3+, Ce3+)phosphor films by sol–gel soft lithography

Abstract

Silicate oxyapatite La9.33(SiO6)4O2:A(A = Eu3+,Tb3+ and/orCe3+)phosphor films and their patterning were fabricated by a sol–gel process combinedwith soft lithography. X-ray diffraction(XRD), Fourier transform infraredspectroscopy, atomic force microscopy, optical microscopy and photoluminescencespectra, as well as lifetimes, were used to characterize the resulting films. The resultsof XRD indicated that the films began to crystallize at 800 °Cand the crystallinity increased with the increase in annealing temperatures.Transparent nonpatterned phosphor films were uniform and crack-free, whichmainly consisted of rodlike grains with a size between 150 and 210 nm.Patterned thin films with different bandwidths(20, 50µm) wereobtained by the micromoulding in capillaries technique. The doped rare earth ions(Eu3+, Tb3+ andCe3+)showed their characteristic emission in crystalline La9.33(SiO6)4O2phosphor films, i.e. Eu3+5D0 −−7FJ(J = 0, 1, 2, 3, 4), Tb3+5D3,4 −−7FJ(J = 3, 4, 5, 6)and Ce3+ 5d(2D)−− 4f(2F2/5,2F2/7)emissions, respectively. Both the lifetimes and PL intensity of the Eu3+, Tb3+ ionsincreased with increasing annealing temperature from 800 to 1100 °C,and the optimum concentrations for Eu3+, Tb3+were determined to be 9 and 7 mol% of La3+ in La9.33(SiO6)4O2films, respectively. An energy transfer from Ce3+ toTb3+was observed in the La9.33(SiO6)4O2:Ce,Tb phosphor films, and the energy transfer efficiency was estimated as a function of Tb3+concentration.