Mesoporous silica modified luminescent Gd2O3:Eu nanoparticles: physicochemical and luminescence properties (original) (raw)
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Materials Science and Engineering: B, 2019
In this paper, the experimental parameters that control the monodisperse and high quality Gd 2 O 3 :Eu 3+ and Gd 2 O 3 :Eu 3+ @silica nanospheres (NSPs) systematically investigated. Gd 2 O 3 :Eu 3+ and Gd 2 O 3 :Eu 3+ @silica NSPs in size range from 100 to 200 nm with a very low standard size deviation of ± 5.00% have been successfully fabricated. The luminescence spectra of Gd 2 O 3 :X%Eu 3+ and Gd 2 O 3 :X%Eu 3+ @silica NSPs were studied as a functions of Eu 3+ ion concentration (X = 3.50; 5.00; 6.00; 7.00; 7.50 and 8.00 at.%). The strongest emission peak at 611 nm corresponding to 5 D 0-7 F 2 transition of Eu 3+ ions in Gd 2 O 3 :Eu 3+ NSPs was very sharp. Interestingly, for the silica coated Gd 2 O 3 :X%Eu 3+ NSPs, a new emission peak at 621 nm was appeared in depend on the coating condition. The intensity ratio of the emission peaks at 611 nm and 621 nm was decreased with the increase of the silica thickness. The highly monodispersed, mesoscaled Gd 2 O 3 :Eu 3+ and Gd 2 O 3 :Eu 3+ @silica NSPs synthesized in this work are high potential for application, especially in photonic crystals, bioimaging and drug delivery.
Morphology- and size-dependent spectroscopic properties of Eu3+-doped Gd2O3 colloidal nanocrystals
Journal of Nanoparticle Research, 2014
The synthesis, morphological characterization, and optical properties of colloidal, Eu(III) doped Gd 2 O 3 nanoparticles with different sizes and shapes are presented. Utilizing wet chemical techniques and various synthesis routes, we were able to obtain spherical, nanodisk, nanotripod, and nanotriangle-like morphology of Gd 2 O 3 :Eu 3? nanoparticles. Various concentrations of Eu 3? ions in the crystal matrix of the nanoparticles were tested in order to establish the levels at which the concentration quenching effect is negligible. Based on the luminescence spectra, luminescence lifetimes and optical parameters, which were calculated using the simplified Judd-Ofelt theory, correlations between the Gd 2 O 3 nanoparticles morphology and Eu 3? ions luminescence were established, and allowed to predict the theoretical maximum quantum efficiency to reach from 61 to 98 %. We have also discussed the impact of the crystal structure of Gd 2 O 3 nanoparticles, as well as coordinating environment of luminescent ions located at the surface, on the emission spectra. With the use of a tunable femtosecond laser system and the Z-scan measurement technique, the values of the effective two-photon absorption cross-section in the wavelength range from 550 to 1,200 nm were also calculated. The nonlinear optical measurements revealed maximum multi-photon absorption in the wavelength range from 600 to 750 nm.
Journal of Materials Engineering and Performance, 2018
A facile direct precipitation method was used for the synthesis of luminescence nanomaterial. Gd 2 O 3 doped with rare earth element Eu 3+ is synthesized by polyol route. The synthesized nanoparticles show their characteristic red emission. The nanoparticles are characterized by x-ray diffractometer (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and photoluminescence (PL) study. The synthesized nanoparticles are spherical particles with $ 30 nm size. The photoluminescence studies show the characteristic Eu 3+ red emission. The PL study shows the intensity of the magnetic dipole transition (5 D 0 ! 7 F 1) at 592 nm compared to that of the electronic dipole transition (5 D 0 ! 7 F 2) at 615 nm. The nanomaterials can show significant application in various display devices and biomedical applications for tracking.
Journal of Nanomaterials, 2013
In this work we have synthesized and characterized new hybrid nanoplatforms for luminescent biolabeling based on the concept of Eu3+complexes encapsulation in mesoporous silica nanoparticles (≈100 nm). Eu complexes have been selected on the basis of their capability to be excited at 365 nm which is a currently available wavelength, on routine epifluorescence microscope. For Eu complexes encapsulation, two different routes have been used: the first route consists in grafting the transition metal complex into the silica wall surface. The second way deals with impregnation of the mesoporous silica NPs with the Eu complex. Using the second route, a silica shell coating is realized, to prevent any dye release, and the best result has been obtained using Eu-BHHCT complex. However, the best solution appears to be the grafting of Eu(TTA)3-Phen-Si to mesoporous silica NPs. For this hybrid, mSiO2-Eu(TTA)3(Phen-Si) full characterization of the nanoplatforms is also presented.
Materials Science and Engineering: C, 2018
Mesoporous multi-layered silica-coated luminescent Y 2 O 3 :Eu nanoparticles (NPs) were prepared by a urea-based decomposition process, and their surfaces were gradually modified with nanoporous and mesoporous silica layers using modified sol-gel methods. The synthesized luminescent core-shell NPs were characterized thoroughly to investigate their structural, morphological, thermal, optical, photo luminescent properties and their surface chemistry. The morphology of the core NPs were nearly spherical in shape and were nano-sized grains. The observed luminescent efficiency of the mesoporous multi-layered silica-coated luminescent core NPs was gradually reduced because of bond formation between the Y 2 O 3 :Eu core and the amorphous silica shell via YeOeSieOH bridges on the surface of the NPs; the bonds suppressed the non-radiative transition pathways. Biocompatibility tests on Human breast cancer cells using the 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and lactate dehydrogenase assays indicated that the core-shell NPs were non-toxic even at high concentrations. The mesoporous SiO 2 layer played a key role in perfecting the solubility, biocompatibility, and non-toxicity of the NPs. The zeta potential, surface chemistry (Fourier transform infrared spectroscopy), and optical absorption spectral analyses revealed the high hydrophilicity of the as-prepared core-shell NPs because of the active surface-functionalized silanol (SieOH) groups, which could potentially offer many exciting opportunities in photonic-based biomedical applications.
Journal of Solid State Chemistry, 2003
The characterization and luminescence properties of nanostructured Gd 2 O 3 :Eu 3+ phosphors synthesized by a sol-lyophilization process are presented. After preparation of gadolinium-based sols from gadolinium nitrate and ammonium hydroxide, the soprepared sols were freeze dried at À101C and calcinated at different temperatures. For temperatures lower than 1300 K, highly crystalline samples with the cubic structure can be obtained without concomitant grain growth of the particles (o50 nm). The luminescence spectra contain all possible transitions of Eu 3+ with C 2 symmetry and present two major features: an increase of the luminescence efficiencies of the phosphors in comparison with that obtained by solid-state reaction and the presence of an additional peak at about 609 nm at the vicinity of the 5 D 0 -7 F 0y4 transition. r
Fluorescence spectroscopy study of mesoporous SiO 2 particles containing Gd 2 O 3 :Eu 3+
Materials Research Express, 2014
Site-selective and fluorescence line narrowing (FLN) laser spectroscopy was used to study the structure of Eu 3+-doped Gd 2 O 3-based material embedded in the mesopores of submicron-sized monodisperse spherical amorphous SiO 2 particles that are of interest for biomedical applications. The phase composition of the material in the pores was determined and the transformations that occur under heat treatment were studied. The room-temperature homogeneous linewidth of 5 D 0 − 7 F 0 transition of Eu 3+ ions in different Gd 2 O 3 /SiO 2 phases was measured with FLN technique. The radiative lifetime of the 5 D 0 excited state of Eu 3+ ions was measured with time-resolved fluorescence technique; the local field effects on radiative transitions in the composite material are discussed.
Synthesis, Structural and Luminescent Properties of Gd2O3-SiO2: Eu3+ Nanopowder Composites
2006
In view of the improvement of luminescent intensity in classical phosphors, different new techniques of synthesis have been developed. One of them is the sol-gel technique for nanopowder synthesis. Applied to a binary system Gd 2 O 3 -SiO 2 doped with trivalent europium ion, very fine powder form samples have been obtained. In that case the emission intensity of 5 D 0 →F 2 electronic transition of 4f 6 configuration is greatly enhanced compared to the bulk oxide. The lifetime measurements are given too. The size of nanoparticles is of about 10 nm, determined by dynamic light scattering and XRD analysis.
Surface Science, 2006
SiO 2 @Gd 2 MoO 6 :Eu 3+ core-shell phosphors were prepared by the sol-gel process. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectra (EDS), transmission electron microscopy (TEM), photoluminescence (PL) spectra as well as kinetic decays were used to characterize the resulting SiO 2 @Gd 2 -MoO 6 :Eu 3+ core-shell phosphors. The XRD results demonstrate that the Gd 2 MoO 6 :Eu 3+ layers on the SiO 2 spheres begin to crystallize after annealing at 600°C and the crystallinity increases with raising the annealing temperature. The obtained core-shell phosphors have a near perfect spherical shape with narrow size distribution (average size ca. 600 nm), are not agglomerated, and have a smooth surface. The thickness of the Gd 2 MoO 6 :Eu 3+ shells on the SiO 2 cores could be easily tailored by varying the number of deposition cycles (50 nm for four deposition cycles). The Eu 3+ shows a strong PL luminescence (dominated by 5 D 0 -7 F 2 red emission at 613 nm) under the excitation of 307 nm UV light. The PL intensity of Eu 3+ increases with increasing the annealing temperature and the number of coating cycles.
Journal of Alloys and Compounds, 2006
In this paper is given a synthesis of Gd 2 SiO 5 (GSO) host lattice doped with Eu 3+ ions using silica sol obtained by hydrothermal method as a main precursor for its nanostructure designing. X-ray diffraction, dynamic light scattering and transmission electron microscopy show that synthesized nanopowder has particle size around 10 nm. These nanosized materials exhibit strong red emission at 614 nm. Lifetime measurements have been performed on two Eu 3+ emitting levels, 5 D 1 and 5 D 0 . 1.37 ms is obtained for the 5 D 0 emitting level while the 5 D 1 emission is fast about 10 s. (M.D. Dramićanin). rare earth silicates belong to the important phosphors which have extensive applications .