Red‐Emitting Magnetic Nanocomposites Assembled from Ag‐Decorated Fe₃O₄@SiO₂ and Y₂O₃:Eu³⁺: Impact of Iron‐Oxide/Silver Nanoparticles on Eu³⁺ Emission

Abstract

The new multistep approach for co-assembling magnetic iron oxide nanoflowers with red-emitting Y 2 O 3 :Eu 3 + to form luminescent and magnetic nanocomposites was reported. The Fe 3 O 4 core prepared by solvothermal method was layered by SiO 2 shell and decorated with small size spherical Ag nanoparticles as well as further coated with Y 2 O 3 :Eu 3 + luminophore. The nanoflower shape Fe 3 O 4 core of size~110 nm and crystalline cubic structure of bifunctional iron-oxide@Y 2 O + (1 mol%) nanomaterials were confirmed from X-rays diffraction, EDS spectra and transmission electron microscopy (TEM) images. The static magnetic measurements supported and manifested nonsuperparamagnetic behavior of the materials at 300 K. The iron oxides are usually luminescence quenchers. In order to rationalize this effect, their optical properties based on their emission spectral data and luminescence decay curves were studied. Experimental intensity parameters (W l ), lifetimes (t), intrinsic quantum yield (Q Ln Ln ) as well as radiative (A rad ) and nonradiative (A nrad ) decay rates were calculated to probe the local chemical environment of the Eu 3 + ion and to better understand the phenomena of iron oxide induced luminescence quenching. The highest value of the intrinsic quantum yield (Q Ln Ln = 74%) for the a-Fe 2 O 3 @Y 2 O 3 :Eu 3 + (1 mol%) among all the luminescent and magnetic nanocomposites suggests that a-Fe 2 O 3 phase induces a lower luminescence quenching then Fe 3 O 4 /g-Fe 2 O 3 . The SiO 2 thin layer leads to improve the luminescence efficiency, whereas the Ag nanoparticles act as luminescence quencher. These novel Eu 3 + nanomaterials may act as a red emitting layer for magnetic and light converting molecular devices.[a] Dr.

Structural and optical properties of europium‐ and titanium‐doped Y2O3 nanoparticles

“…Emission spectra excited at different energies in the VUV and UV range (Figure ) exhibited, for the Eu‐doped materials, the characteristic emission lines from 5 D 0 → 7 F J (580–750 nm) and with lower intensity 5 D 2,1 → 7 F J (450–580 nm) transitions of Eu 3+ in Y 2 O 3 . The emission spectra were very similar to other Y 2 O 3 :Eu 3+ materials described in the published literature and indicated that, independently of the synthesis method, Eu 3+ ions occupied the same microsymmetry. Excitation energy above and below the band gap did not interfere with the emission profile, indicating that the Eu 3+ ions occupying C 2 and S 6 sites were excited from the same decay channels.…”

Enhanced Temperature-Sensing Behavior of Ho3+–Yb3+-Codoped CaTiO3 and Its Hybrid Formation with Fe3O4 Nanoparticles for Hyperthermia

“…Thus, when Fe 3 O 4 is incorporated with CaTiO 3 :Ho,Yb, most of the excited-state energy is being utilized by the spin−spin domain of the paramagnetic nanoparticles, thus quenches the photoluminescence intensity. 38,39 Figure 6b depicts the CIE The ET between Ho 3+ and Yb 3+ ions can also be understood by the mechanism as illustrated in the Figure 7. Upon NIR excitation (980 nm), Ho 3+ electron gets excited to 5 I 6 state through the ground-state absorption (GSA).…”

“…As Fe 3+ is a paramagnetic system (basically d configured) in which excited-state energy is utilized in a spin–spin domain of the MNPs. Thus, when Fe 3 O 4 is incorporated with CaTiO 3 :Ho,Yb, most of the excited-state energy is being utilized by the spin–spin domain of the paramagnetic nanoparticles, thus quenches the photoluminescence intensity. , Figure b depicts the CIE chromaticity diagram. The coordinates are (0.33, 0.43), (0.32, 0.66), and (0.34, 0.39) for 5, 10, and 15%, respectively.…”

Protein Corona Formation on Magnetic Nanoparticles Conjugated with Luminescent Europium Complexes

“…The fine structure and the relative intensities of these transitions can be used to probe the local environment of the Eu 3+ ion and give information on the point group symmetry of the Eu 3+ site in the compounds ,. The important characteristics of these 4 f intraconfigurational transitions can be described as: i ) 5 D 0 → 7 F 1 is magnetic dipole transition, which intensity is largely independent of the chemical environment; ii ) 5 D 0 → 7 F 2 is electric dipole hypersensitive transition, which intensity is very strongly dependent on chemical environment and by far mostly influenced by small angular changes in the local coordination geometry,; iii ) 5 D 0 → 7 F 4 is electric dipole transition, which intensity is also dependent on chemical environment, but not hypersensitive and by far the most sensitive to lanthanide‐ligating atom bond distances and, therefore, to covalency.…”