Eu Nanorods Research Articles

Excellent yellow emission of Si3N4:Eu nanorods derived from waster silicon with better thermal stability for white LEDs

The core issue of light emitting diodes (LEDs) for actual application is the thermal stability of phosphors. Silicon nitride (Si 3 N 4 ) is generally recognized as especially important structural material due to its excellent mechanical properties at extreme high temperature. In this work, Si 3 N 4 : Eu was demonstrated to be an excellent luminescence functional material for LEDs. The discarded corner-waster silicon raw material was utilized to act as the precursor. The Si 3 N 4 :Eu phosphor was synthesized by a facile nitriding process at elevated temperature. The pure α-Si 3 N 4 :Eu nanorods were successfully obtained by adjusting the doping concentration of Eu. It is coexistence with mixed-valence (divalent and trivalent) for Eu in α-Si 3 N 4 according to X-ray photoelectron spectroscopy. The synthesized α-Si 3 N 4 :Eu nanorods showed bright yellow under the excitation of 365 nm (UV) and white luminescence by 460 nm chip (Blue). The Si 3 N 4 :Eu nanorods possess excellent thermal stability, maintains nearly 70% of the origin intensity even at temperatures over 300 °C. The Si 3 N 4 :Eu nanorods demonstrated comparable performance to commercial YAG:Ce 3+ (YAG). Moreover, the long-term thermal stability of Si 3 N 4 :Eu nanorods is superior to commercial YAG, revealing the enhanced service performance. This work not only presents a facile Si 3 N 4 :Eu nanorods green synthesis route from waste utilization, but also offers an enhanced service performance for the high temperature LEDs application.

Morphology control and luminescent properties of Eu/Tb-doped calcium carbonate nanoparticles using natural limestone

The Eu/Tb-doped CaCO3 nanocrystals including nanoneedles, nanorods and nanospheres are respectively synthesized from natural limestone via carbonation technique. The doping of Eu/Tb ions can not change the polymorph, but the morphologies and sizes of synthesized CaCO3 differ significantly depending on the species and concentrations of Eu/Tb ions. The undoped CaCO3 nanoneedles exhibit a length of 280–920 nm and a diameter of 55–78 nm, while the 6% Eu doped CaCO3 nanorods exhibit a length of 1.68–2.56 μm and a diameter of 560–680 nm, respectively. The introduction of Tb ions changes the CaCO3 morphology from nanoneedle to irregular sphere and the diameter of CaCO3: 8% Tb primary particle is around 110–200 nm. Under the excitation of 318 nm or 384 nm ultraviolet light, CaCO3: x% Eu nanorods exhibit characteristic emission bands at 360 nm and 420 nm assigned to 4f6 5 d1(t2g) →8S7/2 transition of Eu2+ ions and sharp peaks at 596 nm from the 5D0 →7F1 transitions of Eu3+ ions. XPS data further confirm the coexistence of Eu2+ and Eu3+ ions. The CaCO3: y% Tb nanospheres present intense blue-green emission at 424 nm and 545 nm under excitation at 397 nm, which are originating from both 5D3→7FJ and 5D4→7FJ transitions of Tb3+ ions. However, under 343 nm excitation, in addition to the emission of Tb3+, Eu3+ ions also present intense emissions at 572 nm, 596 nm, 624 nm and 650 nm, which may be caused by the unknown Eu -containing impurities from natural limestone. Whiteemitting and color-tunable photoluminescence performance of CaCO3 nanostructures are realized by regulating the excitation wavelengths and doping ions.

Hydrothermal epitaxy and luminescent properties of LaVO4:Cu,Eu nanorod array films

LaVO4:Cu,Eu nanorod array films have been prepared on Cu substrates by the hydrothermal epitaxy method. Most of the LaVO4 crystallizes into the tetragonal (t-) LaVO4 phase, with a small amount of monoclinic (m-) LaVO4. Cu2+ ions enter the LaVO4 matrix together with Eu3+ ions. An epitaxial layer composed of tightly packed LaVO4:Cu,Eu nanoparticles grows on Cu substrate and the nanorod array is then assembled by LaVO4:Cu,Eu square nanorods growing on the epitaxial layer. The side length of nanorods is tunable from 20∼300 nm by adjusting the reactants concentration. The LaVO4:Cu,Eu nanorods of the array are single crystals and grow along the (101) plane. A lattice rotation occurs at the growth of the LaVO4:Cu,Eu nanorods due to the lattice mismatch between LaVO4 (112) and Cu (110). Based on the experimental results, a formation mechanism including the surface dissolution of the Cu substrate, the epitaxial layer and the self-assembly of the nanorods is proposed for the LaVO4:Cu,Eu nanorod array film. Finally, the LaVO4:Cu,Eu nanorod array films exhibit red emissions, relatively high quantum efficiencies and long lifetimes.

LaPO4:Eu fluorescent nanorods, synthesis, characterization and spectroscopic studies on interaction with human serum albumin

Eu3+ doped LaPO4 fluorescent nanorods (LaPO4:Eu) was successfully fabricated by a hydrothermal process. The obtained LaPO4:Eu nanorods under the optimal conditions were characterized by means of transmission electron microscopy (TEM), X-ray diffraction (XRD) technique, Fourier transform infrared (FTIR), UV–vis absorption and fluorescence spectroscopy. The nanorods with a length of 50–100nm and a diameter of about 10nm, can emit strong red fluorescence upon excitation at 241nm. The FTIR result confirmed that there are lots of phosphate groups on the surfaces of nanorods. In order to better understand the physiological behavior of nanorods in human body, multiple spectroscopic methods were used to study the interaction between the LaPO4:Eu nanorods and human serum albumin (HSA) in the simulated physiological conditions. The results indicated that the nanorods can effectively quench the intrinsic fluorescence of HSA through a dynamic quenching mode with the association constants of the order of 103Lmol−1. The values of the thermodynamic parameters suggested that the binding of the nanorods to HSA was a spontaneous process and van der Waals forces and hydrogen bonds played a predominant role. The displacement experiments verified that the binding site of nanorods on HSA was mainly located in the hydrophobic pocket of subdomain IIA (site I) of HSA. The binding distance between nanorods and HSA was calculated to be 4.2nm according to the theory of Förster non-radiation energy transfer. The analysis of synchronous fluorescence, three-dimensional fluorescence (3D) and circular dichroism (CD) spectra indicated that there the addition of LaPO4:Eu nanorods did not caused significant alterations in conformation of HSA secondary structure and the polarity around the amino acid residues.

High-efficiency X-ray luminescence in Eu3+-activated tungstate nanoprobes for optical imaging through energy transfer sensitization.

X-ray luminescence optical imaging has been recognized as a powerful technique for medical diagnosis due to its deep penetration and low auto-fluorescence in tissues. However, the low luminescence efficiency of current X-ray luminescence nanoprobes remains a major hurdle for sensitive bioimaging in practical medical applications. Here we present a new kind of energy transfer-sensitized X-ray luminescence nanoprobe (PEG-NaGd(WO4)2:Eu) for highly effective optical bioimaging. Under X-ray excitation, the tungstate host absorbs the X-ray photons and then transfers the energy to the Eu3+ luminescence center, thus enhancing the luminescence efficiency of the nanoprobes for high sensitivity optical in vivo imaging. Moreover, the shortened T1 relaxation response of Gd3+ ions and X-ray attenuation capability of W atoms enable the nanoprobes to serve as efficient contrast agents for magnetic resonance imaging (MRI) and computed tomography (CT) imaging. Therefore, combined with the MRI, CT and X-ray luminescence imaging capabilities, the present PEG-NaGd(WO4)2:Eu nanoprobes could be used as promising multimodal imaging contrast agents in biological systems.

Catechin caged lanthanum orthovanadate nanorods for nuclear targeting and bioimaging applications

Uniform nanocrystalline LaVO4: Eu nanorods have been successfully prepared through a simple solution based hydrothermal process using catechin hydrate as a ligand. Thermogravimetric, CHN, and zeta potential analysis confirmed the coating of catechin hydrate on the surface of LaVO4. The use of Eu3+ ions resulted in a red luminescence of the products, with an emission maximum at 618nm. Laser flash photolysis of these luminescent nanorods demonstrated a photoluminescent decay time of milliseconds. In vitro assays performed with HaCaT cells validated the feasibility of these nanorods to serve as nuclear nano bioprobe. Nanorods emission was observed in the cells by confocal microscopy. In addition, red emitter nanorods displayed no cytotoxicity over a wide concentration ranging namely 10μg–500μg by MTT cell viability assay. These results suggest that LaVO4: Eu nanorods possess the potential to serve as a luminescent probe in bioimaging and nuclear targeting applications.

Laser Spectroscopy of GdPO4 · nH2O:Eu Nanomaterials

One-dimensional GdPO4 . nH2O:Eu nanowires and nanorods of different sizes and the same structure were synthesized by hydrothermal method. Nanowire and nanorods had width and length of about 10 nm/50 nm and 80 nm/1 µm, respectively. Adjusting reaction system PH value by adding alkali metal NaOH, the size and shape of the product can be tuned. The high resolution spectra, excitation spectra, and laser selective excitation spectra at low temperature were determined. Nanorod compared with nanowire, photoluminescence was enhanced, and the excitation spectrum and laser selective excitation spectra were broadened. These results suggest that Eu3+ in GdPO4 . nH20 nanorod and nanowire were located in different local environments.

Facile fabrication of MIL-103(Eu) porous coordination polymer nanostructures and their sorption and sensing properties.

Nano/microscale lanthanide porous coordination polymer MIL-103(Eu) [Eu(BTB)] (H3BTB = 4,4',4''-benzene-1,3,5-triyl-tribenzoic acid) crystals have been fabricated at room temperature by a facile, convenient and environmentally friendly method. The structures of the products were confirmed by powder X-ray diffraction, and the crystal morphologies, including microrods, nanorods and nanospheres, were characterized by scanning electron microscopy. It is found that the addition of sodium acetate and the concentration of the reactants have an important impact on the morphology and size of the MIL-103(Eu) crystals. Gas adsorption measurements reveal that the products show high specific surface areas among the rare earth based coordination polymers and the MIL-103(Eu) nanorods can selectively adsorb CO2 over N2 under ambient conditions. Furthermore, all the products exhibit red emission corresponding to the (5)D0→(7)F2 transition of the Eu(iii) ion, and MIL-103(Eu) nanorods display sensitive and selective sensing for Cu(ii) ions and acetone molecules in solution.

Fabrication of RGD-conjugated Gd(OH)3:Eu nanorods with enhancement of magnetic resonance, luminescence imaging and in vivo tumor targeting.

The development of multimodal probes with magnetic resonance imaging (MRI) and intraoperative fluorescence imaging is the most challenging task in the field of tumor diagnosis. Herein, a simple one-pot hydrothermal method is used to prepare Eu-doped Gd(OH)3 nanorods (Gd(OH)3:Eu NRs) with good fluorescence and the longitudinal relaxivity r1 value of 4.78 (Gd mM s-1). After dual-functionalized maleimide-polyethylene glycol-succinimide (Mal-PEG-NHS) macromolecules are coated on the surface of Gd(OH)3:Eu NRs (PEG-NRs), the results of a lower degradation ratio in newborn calf serum (NCS), reactive oxygen species (ROS) generation in L929 cells and the hemolytic rate of PEG-NRs show their good cyto-compatibility and longer blood circulation time. Moreover, the actively tumor-targeting properties are endowed to NRs through the conjugation of cyclic arginine-glycine-aspartic acid (cRGD) (denoted RGD-NRs). The bio-distributions of RGD-NRs in tumor-bearing nude mice via tail-vein injection indicate that RGD-NRs are specifically taken-up by gliomas. The tests of in vivo T1-weighted MR imaging via tail-vein injection confirm that RGD-NRs possess a higher positive signal-enhancement ability in gliomas. Besides, the better luminescence imaging of living cells under a fluorescence microscope and the clear in vivo fluorescence imaging further confirm the targeting properties and better in vivo optical imaging behavior of RGD-NRs.

Structural and optical properties of highly crystalline Ce, Eu and co-doped ZnO nanorods

Different concentrations of europium (Eu), cerium (Ce) doped and co-doped ZnO:Eu (1%), Ce (1%) nanorods were successfully synthesized by chemical method using Polyvinylpyrrolidone as a surfactant. Crystalline phase, morphology, functional groups, optical absorption, emission and thermal properties of prepared samples were investigated by X-ray diffraction (XRD), X-ray photoelectron spectrometer (XPS), Scanning electron microscopy (SEM), High-resolution transmission electron microscopy (HR-TEM), Fourier transform infra-red (FT-IR), UV–visible, Photoluminescence (PL) spectrophotometer and thermogravimetry (TG) and differential thermal analysis (DTA) analysis. The XRD study showed high crystalline nature of the products with nanoscale regime. Optical study showed shifting the absorption and emission spectra toward higher wavelength side when increasing the doping concentrations. Mainly, this is first time observed a red emission peak at 660nm for Ce (3%) doped ZnO. Additionally, co-doped ZnO:Eu (1%), Ce (1%) nanorods were synthesized and studied their optical properties. This work demonstrates that simply modified their optical absorption and emission of ZnO by introducing rare earth ions can be used as an effective electrode material in solar cell applications, optoelectronic devices and photocatalysis analysis.

Characterizations, structure and optical properties of ZnWO4:Eu nanorods under high temperature

ZnWO4:Eu nanorods were characterized by SEM, TEM, XRD and Raman spectroscopy. The optical properties were investigated by UV–vis and photoluminescence spectroscopy. The temperature‐dependent structure and optical properties of ZnWO4:Eu nanorods have been investigated. It was found that temperature‐induced monoclinic phase to molten state transition occurred at 1573 K. The ZnWO4 intrinsic luminescence and Eu3+ emission intensities decreased rapidly with the increase of temperature. Copyright © 2014 John Wiley & Sons, Ltd.

1D structure of Y2O3:Eu nanorods: controllable synthesis, growth mechanisms and luminescence properties.

Y2O3O:Eu nanorods were successfully synthesized by a facile and effective hydrothermal method in the presence of P123 (EO106PO70EO106) as the surfactant followed by a subsequent heat treatment process. The scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images indicate that the as-prepared samples consist of nanorods with diameters ranging from 80 nm to 100 nm and grow along the (100) direction. The growth mechanism of the as-obtained Y2O3:Eu nanorods was proposed on the basis of pH-dependent experiments. It is found that the pH is a crucial factor in determining the phase, morphology and luminescence properties of Y2O3:Eu nanorods. The luminescent spectra of Y2O3:Eu nanorods show the strong characteristic dominant emission of the Eu3+ ions at 613 nm.

Facile Synthesis of Single‐Phase Mesoporous Gd2O3:Eu Nanorods and Their Application for Drug Delivery and Multimodal Imaging

In this work, a new and facile strategy is developed to synthesize a single‐phase Eu3+‐doped mesoporous gadolinium oxide nanorods (MS‐Gd2O3:Eu@PEG) by incorporating a facile wet‐chemical route, which includes an induced silica layer being coated onto the nanorods, and evolution of pores and formation of channels, as well as a surface‐modified process for multimodal imaging and anti‐cancer drug delivery. The properties of these as‐prepared Gd2O3:Eu nanorods are characterized by transmission electron microscopy (TEM), X‐ray diffraction (XRD), N2 adsorption/desorption, and photoluminescence (PL). The in vitro cytotoxicity test, drug loading, and drug release experiments reveal that the MS‐Gd2O3:Eu@PEG nanorods have good biocompatibility, efficient loading capacity, and pH‐sensitive releasing behavior, suggesting the nanorods could be an ideal candidate as drug delivery vehicles for cancer therapy. Furthermore, the MS‐Gd2O3:Eu@PEG nanorods show clearly dose‐dependent contrast enhancement in T1‐weighted magnetic resonance images and can potentially be used as a T1‐positive contrast agent. These results indicate our prepared multifunctional mesoporous gadolinium oxide nanorods can serve as a promising platform for simultaneous anti‐cancer drug delivery and multimodal imaging.

Pressure effect on the Raman and photoluminescence spectra of Eu3+-doped Na2Ti6O13 nanorods

Eu3+-doped Na2Ti6O13 (Na2Ti6O13:Eu) nanorods with diameters of 30 nm and lengths 400 nm were synthesized by hydrothermal and heat treatment methods. Raman spectra at ambient conditions indicated a pure monoclinic phase (space group C2/m) of the nanorods. The relations between structural and optical properties of Na2Ti6O13:Eu nanorods under high pressures were obtained by photoluminescence and Raman spectra. Two structural transition points at 1.39 and 15.48 GPa were observed when the samples were pressurized. The first transition point was attributed to the crystalline structural distortion. The later transition point was the result of pressure-induced amorphization, and the high-density amorphous (HDA) phase formed after 15.48 GPa was structurally related to the monoclinic baddeleyite structured TiO2 (P21/c). However, the site symmetry of the local environment around the Eu3+ ions in Na2Ti6O13 increased with the rising pressure. These above results indicate the occurrence of short-range order for the local asymmetry around the Eu3+ ions and long-range disorder for the crystalline structure of Na2Ti6O13:Eu nanorods by applying pressure. After releasing the pressure from 22.74 GPa, the HDA phase is transformed to low-density amorphous form, which is attributed to be structurally related to the α-PbO2-type TiO2.

La(OH)3:Ln3+ (Ln=Sm, Er, Gd, Dy, and Eu) nanorods synthesized by a facile hydrothermal method and their enhanced photocatalytic degradation of Congo red in the aqueous solution

The stable and crystalline phase Ln (Ln=Sm, Er, Gd, Dy, and Eu) doped La(OH)3 (La(OH)3:Ln3+) nanorods were synthesized by a facile hydrothermal method. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to examine the microstructure and morphology. The analysis reveals that the obtained compounds are one-dimensional (1D) rod-like nanostructures. The photodegradation of La(OH)3:Ln3+ nanorods was tested by measuring the degradation of azo dye Congo red (CR). The experiments demonstrated that La(OH)3:Ln3+ nanorods degraded CR much faster than undoped La(OH)3 nanorods and the photodegradation efficiency of La(OH)3:Ln3+ nanorods was significantly higher than that of undoped La(OH)3 nanorods.

Chemical Conversion Synthesis and Luminescence Properties of Hexagonal-NaYF4: Eu Nanorods

Chemical Conversion Synthesis and Luminescence Properties of Hexagonal-NaYF4: Eu Nanorods

铕掺杂氧化锌纳米棒阵列材料的制备及光学性能研究

The Eu-doped ZnO(ZnO∶Eu) nanorod arrays have been successfully synthesized on nanoporous silicon pillar array(NSPA) substrates by hydrothermal method.The effective energy transfer from ZnO host to the doping ions has been revealed.The ZnO∶Eu nanorod arrays could enrich the emissions of ZnO nanostructure,moreover,the fabrication method is simple under mild reaction condition.The presence of trivalent europium ions in ZnO crystal lattice has been confirmed by X-ray diffraction(XRD) and X-ray photoelectron spectroscopy(XPS).Under the ultraviolet(UV) laser excitation,ZnO-related UV and near band energy blue-green emission and Eu3+-related red emission were observed,which were attributed to the emission of ZnO,the band edge transition,the intrinsic defects and the Eu3+ ions transition,respectively.Based on the energy band diagram,the photoluminescence(PL) mechanism has been discussed,as well as energy transfer occurs from ZnO host to Eu3+ ions through intrinsic defects states of ZnO in ZnO∶Eu nanorods structure.

PEGylation of fluoridated hydroxyapatite (FAp):Ln3+ nanorods for cell imaging

PEGylation is a popular approach for the surface functionalization of nanoparticles to achieve improved properties and better performance. Herein, we developed a facile method for surface PEGylation of hydrophobic fluoridated hydroxyapatite (FAp):Ln3+ (Ln = Eu or Tb) nanorods via hydrophobic interactions between oleic acid and amphiphilic synthetic copolymers, which were synthesized through reversible addition-fragmentation chain transfer (RAFT) polymerization using stearyl methacrylate (SMA) and poly(ethylene glycol) methacrylate (PEGMA) as monomers. Our results demonstrated that the morphology and fluorescent properties of the FAp nanorods are not significantly changed by the PEGylation procedure, and the resulting FAp nanorods were found to be stable in aqueous solution. More importantly, these PEGylated FAp nanorods are biocompatible with cells and could be utilized for cell imaging applications. Therefore, we believe that the method described in this work is a simple, efficient and general strategy for the surface PEGylation of hydrophobic nanoparticles.

Catalytic photodegradation of Congo red in aqueous solution by Ln(OH)3 (Ln = Nd, Sm, Eu, Gd, Tb, and Dy) nanorods

The stable and crystalline phase pure Ln(OH)3 (Ln=Nd, Sm, Eu, Gd, Tb, and Dy) nanorods were synthesized by a facile hydrothermal method starting with corresponding rare-earth chloride hexahydrate LnCl3·6H2O, ammonia NH3·H2O and cationic surfactantcetyltrimethylammonium bromide (CTAB). X-ray powder diffraction (XRD) and transmission electron microscopy (TEM) were used as the structural probes in order to check the phase purity, and to examine the morphologies and microstructures of the synthesized compounds. The structural analysis reveals that the obtained compounds are rare-earth hydroxides with one-dimensional (1D) rod-like nanostructures. The formation mechanism of the Ln(OH)3 nanorods was also proposed. The photoactivity of Ln(OH)3 (Ln=Nd, Sm, Eu, Gd, Tb, and Dy) nanorods was tested by measuring the degradation of azo dye Congo red (CR). The results show an excellent removal capacity for organic pollutants CR from wastewater, making them promising candidates for the wastewater treatment.

Synthesis, characterization and photoluminescent properties of rare-earth hydroxides and oxides nanorods by hydrothermal route

The stable and crystalline pure phase Ln(OH)3 (Ln=La, Nd, Sm, Eu, Gd, Tb, and Dy) nanorods are synthesized by a facile hydrothermal method using the simple chemical materials (rare-earth chloride hexahydrate LnCl3⋅6H2O and NH3⋅H2O) and polymer polyvinypyrrolidone (PVP). The as-prepared Ln(OH)3 nanorods can be successfully converted to Ln2O3 nanorods via calcination under appropriate conditions. X-ray diffraction (XRD) spectra, Fourier transformed infrared (FTIR) spectrum, scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-Resolution TEM (HRTEM), and Raman spectroscopy were used to examine the morphologies and microstructures to find out the cause. The analyzed results indicate that the obtained nanorods are rare-earth hydroxides and oxides with 1D nanostructures. The formation mechanism of the Ln(OH)3 and Ln2O3 nanorods was investigated. Optical properties of the Ln(OH)3 and Ln2O3 nanorods were determined by photoluminescence (PL). Ln(OH)3 and Ln2O3 nanorods exhibit a strong blue emission with the strongest narrow bands at about 469 nm corresponding to the intra-4f transitions 5D2→7F6, which have potential applications in fluorescent devices.