Doped Gd2O3 Nanoparticles Research Articles

Facile fabrication and technical analysis of copper doped Gd2O3 nanoparticles: Photocatalytic elimination of Rhodamine B dye under UV light

The current study concentrates on the facile fabrication of copper doped Gd2O3 nanoparticles by facile chemical route. The materials were characterized by XRD, FTIR, PSA, SEM, EDAX and UV-visible spectroscopy. The optical band gap (Eg) was found to be in the range of 3.10–4.29 eV. The materials exhibited better photocatalytic efficiency in degrading Rhodamine B (RhB) under UV light. Among the materials studied, 0.075 g Gd1.70Cu0.30O3-δ photocatalyst material has degraded 82% of RhB at a pH of 4.3 in 80 min.

Synthesis, characterization and effect of dopant on magnetic hyperthermic efficacy of Gd2O3 nanoparticles

Rare-earth oxides are paramagnetic materials and their high magnetic susceptibility in the bulk makes them potentially promising materials, but the magnetic properties of their nanoparticles remain incompletely characterized. We explore the effect of dopant (Tb3+ and Eu3+) in Gd2O3 host lattice as a heating agent for magnetic hyperthermia application. The structural, optical, and magnetic properties of the pristine, Gd2O3:Tb3+ and Gd2O3:Eu3+ nanocrystals were studied by XRD, HR-TEM, FTIR, and VSM. XRD analysis revealed the presence of mixed-phase (cubic and monoclinic) in pristine, and doped Gd2O3 nanoparticles. The morphological information has been observed with the help of HRTEM and the calculated inter-planar spacing is in well agreement with JCPDS data. Particles are nearly spherical and diameter ∼15 nm, estimated from HRTEM image. FTIR spectroscopic analysis confirms the presence of Gd-O-Gd stretching at 583cm−1. We confirmed the paramagnetic nature for all samples using VSM analysis. The self-heating capability of prepared samples are investigated by performing the induction heating experiment and it is assessed through calculated SAR and ILP values with help of Box-Lucas fitting model where 10% Tb3+ doped Gd2O3 has maximum values.

Step by step rare-earth catalyzed SiOx annealing and simultaneous formation of Europium- silicide by low coverage of Eu doped Gd2O3 nanoparticles

We report the formation of silicide by annealing of a SiOx surface, with low coverage of Eu doped Gd2O3 nanoparticles. The annealing temperature required for removal of native oxide from the Si substrate decreases with close to 200 °C in presence of the nanoparticles. X-ray photoemission electron microscopy, low-energy electron microscopy and mirror electron microscopy are used to monitor the silicide formation and SiOx removal. Fragmentation of the nanoparticles is observed, and the SiOx layer is gradually removed. Eu migrates to clean Si areas during the annealing process, while Gd is found in areas where oxide is still present. This annealing process is clearly facilitated in the presence of rare-earth based nanoparticles, where nanoparticles are suggested to function as reaction sites to catalyze the oxygen removal and simultaneously form Eu based silicide. Reduction of the annealing temperature of SiOx substrates is also observed in presence of pure Eu3+ and Gd3+ ions. Simultaneous oxygen removal and EuSi formation enable this new rare-earth catalyzed annealing and silicide formation to find applications both within optoelectronics and processing microelectronic industry.

Warm white broadband emission and tunable long lifetimes in Yb3+ doped Gd2O3 nanoparticles

Upconversion luminescence materials have stimulated growing attention in photovoltaic cell owning to the ability of converting a few low-energy photons into a single high-energy photon. However, there still remains a daunting challenge to achieve upconversion emission covering the entire visible spectrum in a single material. Here, an incandescent broadband white upconversion emission covering the entire visible region is realized in a single Gd2O3:Yb3+ nanoparticles by utilization of adverse multiphonon relaxation. Importantly, tunable long fluorescence lifetime can be synchronously implemented in the single material, where the lifetime range spans one order of magnitude. Furthermore, benefiting from the broadband emission, the luminescence intensity achieves 482-fold improvement as the power increase from 0.53 W to 1.51 W. These broadband emissions are enabled by engineering the pathways of nonradiative de-excitation via multiphonon relaxation. Based on the kinetic analysis and mechanism research, the photon avalanche is demonstrated to play an important role for broadband emission. The warm white emission together with its tunable long lifetime provides a new avenue for developing single emitter-based white-light-emission materials for next-generation display and lighting technologies.

Evaluation of in vivo immunotoxicity for Ho3+-doped Gd2O3 nanoparticles as dual-modality nanoprobes

Rare-earth-doped gadolinium-oxide (Gd2O3) nanoparticles (NPs) are increasingly used for magnetic resonance imaging (MRI) and optical imaging (OI). However, to date, the poor data of in vivo hazard assessment has been one obstacle to its clinical deployment, especially the relative immunotoxicity in vivo. In this paper, we synthesized Ho3+-doped Gd2O3 NPs (HoNPs) for MRI and OI by laser ablation in liquid. To the best of our knowledge, we present here the most extensive biocompatibility in vitro (cell viability and apoptosis) and in vivo relative immunotoxicity (the level of cluster-of-differentiation (CD) markers in peripheral blood and relative gene expression of toxicity in the liver) in Balb/c mice. Our results indicate that HoNPs with satisfactory biocompatibility can be used as MRI (r1 relaxivity of 5.01 mM-1 s-1) and OI (strong blue fluorescence) dual-modal contrast agents in vitro. Importantly, there were significant differences in the expression levels of CD25, CD69, CD71, protein 38 (P38), extracellular regulated protein kinase (ERK), c-Jun N-terminal kinase (JNK), and protein 53 (P53) between the negative control and the HoNPs at 7 d after injection (p < 0.05). In conclusion, this work suggests that the nano-structure of HoNPs may reduce in vivo relative immunotoxicity. Therefore, it will be crucial to evaluate the above- mentioned indexes on in vivo relative immunotoxicity at 7 d after injection of these rare-earth-based biomaterials before molecular imaging in vivo.

Rare Earth Yb3+ Doped Gd2O3 Single Phase Nanophosphors: Structural, Morphological and Photoluminescence Studies

In this paper, a report has been acclaimed on the structural, morphological and photoluminescence properties of the pure and Yb3+ (2, 5 and 10 wt %) doped gadolinium oxide nanophosphor, synthesized by the citrate-nitrate auto combustion method. The influence of doping concentration on the properties of the prepared phosphor was studied using different characterization techniques. Structural studies carried out using XRD revealed crystalline cubic phase for both the pure and doped Gd2O3 nanoparticles. The phase formation and purity were further confirmed from the FTIR spectra. Surface morphology was found using SEM analysis showed the clusters of tiny particles. Optical absorption measurements were recorded in the UV-Vis-NIR wavelength region and the optical band gap variations with dopant concentration were discussed. The probable mechanism for the visible PL emissions by Yb3+ doped Gd2O3 phosphors are explained by different transition phenomenon. Fluorescence lifetime along with energy transfer efficiency from Gd3+ to Yb3+ was determined.

Photoluminescence and thermal stability of Tb3+-doped Gd2O3 nanoparticles embedded in SiO2 host matrix

Terbium doped SiO2-Gd2O3 materials were obtained by a sol-gel process and heat-treated at 1000 °C. The effect of Tb3+concentration on structural, optical and photoluminescent properties of materials are reported here. FT-IR indicated the presence of Gd2O3 and SiO2 in the composition of materials. XRD showed the formation of the Gd2O3 cubic phase without the presence of phase impurities, and lattice parameter calculations indicated the effective inclusion of Tb3+ in Gd2O3 crystalline structure. SEM analysis revealed spherical particles of Gd2O3 and TEM confirmed that these particles are included in the amorphous SiO2. Excitation spectra show bands in the UV-region at characteristic wavelengths of the Gd2O3 host absorption. Emission spectra were collected by changing the excitation, and the intensity shows dependence on the UV photon energy. Tb3+-doped Gd2O3 grown into SiO2 showed higher Tb3+ lifetimes which are ideal for photonic applications. The temperature significantly influenced the luminescence of the materials, with chromaticity changing from green to blue region. The activation energy for thermal quenching (Ea) was determined by an Arrhenius methodology and the material shows a high thermal stability (Ea for thermal quenching = 0.378 eV).

Synthesis and photoluminescent characteristics of Dy3+ doped Gd2O3 phosphors

Pure and dysprosium doped gadolinium oxide nanoparticles for three different concentrations (2, 5 and 10 mol.%) were synthesized by auto-combustion method using citric acid as fuel. The nanoparticles obtained were characterized using powder x-ray diffraction (XRD), Fourier transform infrared (FTIR), scanning electron microscopy (SEM), UV–vis–NIR spectroscopy and photoluminescence (PL) spectroscopy techniques. XRD pattern revealed the crystalline cubic phase with space group Ia3 (Space Group: 206) for both the pure and doped Gd2O3 nanoparticles. The metal oxide phase formation and purity of Gd2O3 nanoparticles were further confirmed from the FTIR spectra. Morphology of the pure Gd2O3 powder is loosely dispersed clusters of tiny particles with microscopic pores, whereas for the doped samples aggregates were broken to form small clusters. Optical absorption measurements were recorded in the UV–vis–NIR wavelength region and the optical band gap variations with dopant concentration were discussed. The PL spectra of pure and Dy3+ doped Gd2O3 nanoparticles have been studied and the effect of emitted light on the yellow-to-blue intensity ratio (Y/B) of Dy3+ emission was demonstrated.

Europium-doped gadolinium oxide nanoparticles: A potential photoluminescencent probe for highly selective and sensitive detection of Fe3+ and Cr3+ ions

Herein, we report the facile synthesis, characterizations and photoluminescence sensing probe applications of europium (Eu3+)-doped gadolinium oxide (Gd2O3) nanoparticles. The Eu3+- doped Gd2O3 nanoparticles were synthesized by a facile and straight forward chemical synthesis followed by the calcination process. Various percent concentrations of Eu3+ ranging from 1 to 5% was used to dope into the Gd2O3 and calcine them for different time to optimize the photoluminescence properties of the synthesized nanoparticles. The synthesized nanoparticles were characterized by several techniques which confirmed that the 5% Eu3+- doped Gd2O3 nanoparticles exhibited best structural and optical properties. Thus, due to best structural and optical properties, the 5% Eu3+- doped Gd2O3 nanoparticles were used as photoluminescent probe for the detection of Fe3+ and Cr3+ ions. The detailed sensing results revealed that the synthesized nanoparticles are quite selective and sensitive towards Fe3+ and Cr3+ ions with 99.3% quenching efficiency for 10ppm Fe3+ ions and 98.6% quenching efficiency for 40ppm Cr3+ ions respectively. The detection limit for Fe3+ and Cr3+ ions were 1.48ppm and 6.56ppm respectively. The utilization of synthesized nanoparticles in real water samples with percentage recovery of >90% in tap water and distilled water and 87% in sewage water has unlocked numerous opening to use such nanomaterial for real water treatment applications.

Selective detection of Fe3+, Cr3+ and Cu2+ in water using highly luminescent Gd2O3:Eu3+ nanoparticles

Rod shaped Eu3+ doped Gd2O3 nanoparticles were synthesised by a simple wet-chemical method followed by high temperature heating at 700°C. The nanoparticles were characterised by X-ray diffraction (XRD), infra-red (IR), transmission electron microscopy (TEM), x-ray photonelectron spectroscopy (XPS), photoluminescence (PL) studies and lifetime measurement. The particles show strong host sensitised luminescence in water. Luminescence in water is selectively quenched by Fe3+, Cr3+ and Cu2+ ions. This luminescence quenching phenomenon has been utilised to detect metal ions in synthetic water and environmental water samples. Results obtained by luminescence quenching for environmental water samples are in good agreement with the results obtained from inductively coupled plasma atomic emission spectroscopy (ICP-AES) study.

Facile fabrication of hollow mesoporous Eu3+-doped Gd2O3 nanoparticles for dual-modal imaging and drug delivery

In this paper, we report a facile and reproducible approach to prepare Eu3+-doped gadolinium oxide (Gd2O3) hollow mesoporous nanoparticles (HMNPs) by using polyacrylic acid sodium salt (PAAS) NPs as templates. The synthesized NPs are well-dispersed with a diameter of 120 nm and a wall thickness around 20 nm, which were utilized as nanoprobes for simultaneous dual-modal fluorescence and magnetic resonance (MR) imaging and drug delivery due to their excellent luminescent property and obvious T1-enhancement effect as well as the HM structure. The Eu3+-doped Gd2O3 HMNPs possess the loading capacity for doxorubicin (DOX) as high as 310 μg mg−1 and display the pH-responsive drug release property. In vitro cell cytotoxicity tests on cancer cells verify that the DOX loaded Eu3+-doped Gd2O3 HMNPs have comparable cytotoxicity with free DOX at the same concentration of DOX, while Eu3+-doped Gd2O3 HMNPs alone show no obvious cytotoxicity. In addition, Eu3+-doped Gd2O3 HMNPs exhibit excellent capability in dual-modal fluorescence and MR imaging. Taken together, these findings highlight the fascinating features of Eu3+-doped Gd2O3 HMNPs as dual-modal imaging contrast agents and drug delivery vehicles.

Synthesis and optical properties of Gd2(1−x)O3: 2xEu3+ nanophosphors via tartaric assisted sol–gel route

Gd2(1−x)O3: 2xEu3+ nanophosphors have been successfully synthesized by low temperature sol–gel method using tartaric acid as a chelating agent. The crystallinity, morphology, particle size and optical properties were studied by X-ray diffraction (XRD), scanning electron microscope, transmission electron microscope, Fourier-transform infrared spectroscopy and photoluminescence techniques. XRD profiles indicate that Eu3+ doped Gd2O3 nanoparticles possess highly crystalline cubic structure. Homogenous spherically shaped particles in the nanometer range having no effect of different concentrations of tartaric acid were evidenced by morphological analysis. Optical properties along with chromaticity coordinates of the Gd2(1−x)O3: 2xEu3+ nanophosphors, exhibiting an intense red emission corresponding to 5D0 → 7F2 transition of Eu3+ ions at 612 nm under 254 nm excitation were investigated. Optical studies reveal that emission intensity strongly depends on the sintering temperature, Eu3+ ions concentration as well as molar ratio of dopant ions to chelating agent i.e. tartaric acid. Hence, Eu3+ doped Gd2O3 nanoparticles having color coordinates approaching towards red region with the increasing Eu3+ ions contents seems to be a promising candidate for efficient opto-electronics applications.

Eu(3+)-doped gadolinium oxide nanoparticles synthesized by chemical coprecipitation predicted by thermodynamic modeling.

Thermodynamic modeling of the Gd(3+)-Eu(3+)-O(2-)-CO3(2-)-Cl- system has been adopted as a rational approach to establish routes to the better synthesis conditions for pure phase Eu(3+)-doped Gd2O3 nanoparticles. Quantitative analyses of the different reaction equilibria involved in the coprecipitation of Gd2(CO3)3 and Eu2(CO3)3 x 3H2O from aqueous solutions have been used to determine the optimum synthesis conditions. The characterization and photoluminescence spectra of Gd2O3 nanoparticles doped with Eu3+ activator ions at the concentrations of 1, 2, 3, 4 and 5 mol% synthesized by urea-based homogeneous coprecipitation are presented. The surface of the as-prepared mixture of Gd2(CO3)3 and Eu2(CO3)3 x 3H2O particles are coated with silica to avoid the agglomeration followed by annealing the carbonate precursors at 800 degrees C for 3 hours. Subsequently, the silica shell is removed with an alkali solution resulting in well-crystallized Eu(3+)-doped Gd2O3 nanoparticles. X-ray diffraction (XRD) results show that all the diffraction peaks are well indexed to the cubic Gd2O3 with high crystallinity. The photoluminescence spectra exhibit a characteristic f-f transition band that corresponds to Eu3+. The sharp red emission at 616 nm corresponds to the transition identified as 5D0 __7F2. Both the emission intensity at 616 nm and asymmetry factor of [I(5D0 --> 7F2)/I(5D0 --> 7F1)] exhibit clearly Eu(3+)-doping concentration-dependent luminescence behaviors. The rather fast decay time is closely correlated to the proper occupation of the Eu3+ activator ions in the C2 sites of the Gd2O3 cage, resulting in strong dependence on small changes of the total electric density and defect density. Thus, the best concentration of Eu3+ activator ions for the maximum brightness are the 3 mol% Eu(3+)-doped Gd2O3 at 5D0 --> 7F2 because it shows the longest decay time and more luminescent intensity than the other doping concentrations.

Morphology- and size-dependent spectroscopic properties of Eu3+-doped Gd2O3 colloidal nanocrystals.

The synthesis, morphological characterization, and optical properties of colloidal, Eu(III) doped Gd2O3 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 Gd2O3:Eu3+ nanoparticles. Various concentrations of Eu3+ 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 Gd2O3 nanoparticles morphology and Eu3+ 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 Gd2O3 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.

Size-tunable synthesis of lanthanide-doped Gd2O3nanoparticles and their applications for optical and magnetic resonance imaging

Lanthanide (Ln3+) doped Gd2O3 nanoparticles (NPs) have been prepared via a thermal treatment of gadolinium carbonate precursor, which was obtained by simple hydrothermal treatment of Gd(NO3)3 solution in the presence of urea and glycerol. The size of the nanoparticles could be fine tuned from 270 to 10 nm by varying the amount of glycerol, which acted as a chelating agent to control the size of the nanoparticles. Calcination of the gadolinium carbonate nanoparticles at 500 °C led to the formation of uniform Gd2O3 nanoparticles without any obvious morphology change. By doping the lanthanide ions (Yb, Er/Tm) into the Gd2O3 host matrix, these nanoparticles emitted strong upconversion (UC) fluorescence under 980 nm near infrared (NIR) excitation. Moreover, their emission colors could be tuned by simply changing either the co-dopant concentration or the dopant species. Water dispersibility was achieved by forming a silica layer on the surface of the Gd2O3 nanoparticles. The possibility of using these silica-coated upconversion nanoparticles for optical imaging in vitro/in vivo has been demonstrated. It was also shown that these Gd2O3 nanoparticles brightened the T1-weighted images and enhanced r1 relaxivity of water protons, which suggested they act as T1 contrast agents for magnetic resonance (MR) imaging. Thus, Gd2O3 nanoparticles doped with Ln3+ ions provide the dual modality of optical and magnetic resonance imaging.

Luminescence properties of Dy&lt;SUP align=right&gt;3+&lt;/SUP&gt; doped Gd&lt;SUB align=right&gt;2O&lt;SUB align=right&gt;3 nanoparticles prepared by glycine route: annealing effect

Dy3+ doped Gd2O3 nanoparticles were prepared by glycine-nitrate combustion route and their luminescence properties have been investigated. Through host lattice absorption at 230 nm, emission peaks at 488 (4F9/2 → 6H15/2, blue-green) and 572 nm (4F9/2 → 6H13/2, yellow) of Dy3+ are observed along with a broad emission peak at 400 nm (host). Luminescence intensity increases with increase of heat-treatment from 500°C to 900°C due to extent of reduction of particle surface defect. On increasing the concentration from 1 to 2 at.% Dy3+, luminescence intensity increases slightly and decreases with further increase of Dy3+ due to cross-relaxation among Dy3+ ions. This was supported by lifetime studies. Lifetimes for 4F9/2 level of Dy3+ in 1, 2 and 5 at.% Dy3+ doped Gd2O3 prepared at 900°C were found to be 237, 39 and 26 μs, respectively.

Eu3+-doped Gd2O3 nanoparticles as reporters for optical detection and visualization of antibodies patterned by microcontact printing

Lanthanide oxide nanoparticles are promising luminescent probes in bioanalysis, because of their unique spectral properties, photostability, and low-cost synthesis. We report for the first time the application of europium-doped gadolinium oxide (Eu:Gd2O3) nanoparticles to the optical imaging of antibody micropatterns. The nanoparticles were synthesized by spray pyrolysis and coated with antibody (IgG) molecules by physical adsorption. Our experiments showed that the Eu:Gd2O3 is a good biocompatible solid support for antibody immobilization. The antibodies (anti-rabbit IgG) immobilized on the nanoparticles had excellent biological activity in the specific recognition reaction with rabbit IgG patterned in line strips (10 micromx10 microm) on a glass substrate by use of a micro-contact printing technique. The specific immunoreaction was confirmed by two independent microscopic techniques-fluorescence and scanning electron microscopy (SEM). Both microscopic images revealed that the nanoparticles were organized into designated structures as defined by the microcontact printing process with negligible non-specific binding. The nanoparticles can be used as fluorescent markers in a variety of immunosensing applications in a microscale format.