Luminescent Properties of Eu-Doped Lanthanum Oxyfluoride Sol−Gel Thin Films

Abstract

Highly luminescent Eu 3+ -doped LaOF thin films have been prepared by a sol-gel procedure using La(hfa) 3 diglyme (Hhfa ) 1,1,1,5,5,5-hexafluoro-2,4-pentanedione; diglyme ) bis(2-metoxyethyl)ether) as a singlesource precursor for lanthanum and fluorine. Europium doping (Eu/La ) 3 and 10 atom %) has been achieved by adding the proper amount of europium acetate hydrate (Eu(CH 3 CO 2 ) 3 • xH 2 O, x e 4) to the precursor solution. After single-layer deposition, the obtained coatings were heat treated in air up to 700 °C. All the samples, under UV irradiation, presented a bright red luminescence clearly visible to the naked eye notwithstanding the low europium content and the limited film thickness (e50 nm). The microstructure, composition, and morphology of the samples and their interplay with the synthesis conditions were investigated by glancing incidence X-ray diffraction (GIXRD), X-ray photoelectron spectroscopy (XPS), secondary ion mass spectrometry (SIMS), and field emission scanning electron microscopy (FE-SEM). The luminescence properties of Eu 3+ :LaOF in the energy and time domains are reported and discussed as a function of europium content and synthesis conditions. The observed variations in the light-emitting behavior of Eu 3+ ions have been correlated to the structural and compositional characteristics of the host oxyfluoride matrices.

80SiO2‐20LaF3 oxyfluoride glass ceramic coatings doped with Nd3+ for optical applications

“…The increase in the emission intensity is likely related to the reduction in ‐OH groups with temperature. Concerning to the peak position, the small red‐shift observed as annealing temperature increases has been observed in oxyfluoride thin films and attributed to the formation of oxygen‐rich phases at the expense of fluorine content which produces a small variation on the ligand field acting on the RE ions …”

Efficient Luminescence from Fluorene‐ and Spirobifluorene‐Based Lanthanide Complexes upon Near‐Visible Irradiation

“…The number of J multiplets, their position, and their relative intensity are very similar in the Eu 3+ ⊂ 1 and Eu 3+ ⊂ 2 complexes, clearly indicating an equivalent local coordination geometry for the Eu 3+ sites10, 11, 49 despite the presence of a bulkier chromophore in Eu 3+ ⊂ 2 . It is worth highlighting that in Eu 3+ ⊂ 2 the presence of the spirobifluorene unit allows the sensitized emission to occur up to excitation wavelengths of 420 nm, that is, 20 nm longer relative to Eu 3+ ⊂ 1 (Figure 5b, c).…”

The Role of Ligand Topology in the Decomplexation of Luminescent Lanthanide Complexes by Dipicolinic Acid

“…The transition J =2 is remarkably increased compared with all the others and undergoes a moderate redshift. These changes indicate the occurrence of structural rearrangements around the Eu 3+ center . The behavior of the ratiometric pair is particularly interesting upon excitation at 310 nm, that is, in the spectral region where DPA is not absorbing (Figures a and b).…”