Red‐Emitting Magnetic Nanocomposites Assembled from Ag‐Decorated Fe ₃ O ₄ @SiO ₂ and Y ₂ O ₃ :Eu ³⁺ : Impact of Iron‐Oxide/Silver Nanoparticles on Eu ³⁺ Emission

Abstract

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 3 :Eu 3+ , Fe 3 O 4 @SiO 2 @Y 2 O 3 :Eu 3+ and Fe 3 O 4 @SiO 2 ‐Ag@Y 2 O 3 :Eu 3+ (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 (Ω λ ), lifetimes (τ), intrinsic quantum yield ( ) as well as radiative (A rad ) and non‐radiative (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 ( =74%) for the α‐Fe 2 O 3 @Y 2 O 3 :Eu 3+ (1 mol%) among all the luminescent and magnetic nanocomposites suggests that α‐Fe 2 O 3 phase induces a lower luminescence quenching then Fe 3 O 4 /γ‐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.