Preparation, patterning and luminescent properties of oxyapatite La_9.33(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/or Ce3+) phosphor films and their patterning were fabricated by a sol–gel process combined with soft lithography. X-ray diffraction(XRD), Fourier transform infrared spectroscopy, atomic force microscopy, optical microscopy and photoluminescence spectra, as well as lifetimes, were used to characterize the resulting films. The results of XRD indicated that the films began to crystallize at 800 °C and the crystallinity increased with the increase in annealing temperatures. Transparent nonpatterned phosphor films were uniform and crack-free, which mainly consisted of rodlike grains with a size between 150 and 210 nm. Patterned thin films with different bandwidths(20, 50µm) were obtained by the micromoulding in capillaries technique. The doped rare earth ions(Eu3+, Tb3+ and Ce3+) showed their characteristic emission in crystalline La9.33(SiO6)4O2 phosphor films, i.e. Eu3+5D 0 −−7F J(J = 0, 1, 2, 3, 4), Tb3+5D 3,4 −−7F J(J = 3, 4, 5, 6) and Ce3+ 5d(2D)−− 4f(2F 2/5,2F 2/7) emissions, respectively. Both the lifetimes and PL intensity of the Eu3+, Tb3+ ions increased 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)4O2 films, respectively. An energy transfer from Ce3+ to Tb3+ 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.

Tunable photoluminescence in monodisperse silica spheres

“…Therefore, the employed organo-materials decomposed and organic groups disappeared after annealing. The peaks of broad band at FT-IR spectra all exhibit strong absorption bands associated with the characteristic stretching, bending, and wagging vibrations of silica groups at 1097, 805, and 465 cmÀ1, respectively [35]. The peak at 958 cm À1 arises from the asymmetric stretching vibration of SiO 4 groups.…”

Charge compensation assisted enhanced photoluminescence derived from Li-codoped MgAl2O4:Eu3+ nanophosphors for solid state lighting applications

“…Due to the lower symmetry features, these Mg 2+ sites are very suitable for 4f → 4f transitions of the rare earth activators. 15 The presence of inversion symmetric and non-inversion symmetric sites in MgAl 2 O 4 spinel also affect the spectra of the RE dopant immensely. Being inspired by these excellent characteristics, several researchers have devoted their efforts to develop RE doped MgAl 2 O 4 nanophosphors by different synthesis methods.…”

Infrared photoluminescence of sol–gel spin-coated films of rare-earth activated lanthanum silicate

“…Compounds with the general composition La 9.33 À x À y À z Ln x Ln y 'Ln'' z Si 6 O 26 where Ln, Ln', and Ln''¼Er 3 þ , Ce 3 þ , and Yb 3 þ respectively, were prepared by the sol-gel method accompanied by a spin-coating technique that has proved useful for other rareearth apatite phosphors [18]. While maintaining the intended compositions, the precursor solutions were prepared by mixing stoichiometric amounts of La(NO 3 ) 3 Á 6H 2 O powder (Schalau Chemical 99.9% purity) into a solution of 3 mL acetic acid used as catalyst, 3 mL ethanol, and 1.2 mL deionized water, which was then stirred at 40 1C for 20 min until it became clear.…”