Increasing Gadolinium Content Research Articles

Structure, mechanical, and neutron radiation shielding characteristics of mechanically milled nanostructured (100-x)Al-xGd2O3 metal composites

Metallic substances are favored for storing and transporting spent nuclear fuels (SNFs) due to their thermal stability, mechanical strength, and corrosion resistance. Adding gadolinium (Gd) significantly enhances neutron shielding, improving efficiency with reduced thickness and dimensions. In this study, Al–Gd2O3 metal nanocomposites were synthesized using powder-processed mechanical milling. The crystal structure features of (100-x)Al-x%Gd2O3 samples with varying percentages of Gd2O3 (5 %, 10 %, and 15 % by weight) were analyzed by X-ray diffraction. Microstructural properties were studied using scanning and transmission electron microscopy (SEM and TEM). The synthesized composites' neutron and γ-radiation shielding characteristics were investigated theoretically using the MCNP6.2 transport code. Analysis of the XRD data revealed prominent peak shifts with increased milling time, indicating reduced particle sizes. Differential scanning calorimetry (DSC) indicated Gd2O3-induced changes in temperature behavior, and the Vickers microhardness tests demonstrated enhanced mechanical strength with increasing gadolinium concentration. Improved neutron radiation shielding was observed with higher Gd2O3 content. Our study highlights the potential of Gd2O3-enriched metal matrix composites for advanced industrial applications.

Unveiling the effect of Gd3+ doping on enriching the structural, magnetic, optical, and dielectric properties of biocompatible hematite nanoparticles

This work is an attempt to obtain gadolinium-doped hematite GdxFe2−xO3 (x = 0, 0.05, and 0.1) using the hydrothermal method followed by heat treatment. The work also studies the impact of gadolinium doping on the magnetic, electrical, and optical properties of hematite. X-ray diffraction (XRD) analysis, energy-dispersive X-ray spectroscopy (EDAX) and photoelectron spectroscopy (XPS) showed that the obtained phase for all samples was pure hematite with no evidence of secondary phases, indicating a high solubility limit of gadolinium ions in hematite lattice. The morphology and size distribution of the particles were investigated using high-resolution transmission electron microscopy (HRTEM) and scanning electron microscopy (SEM). It was found that the lattice parameters increased with increasing gadolinium concentration. Magnetization was not enhanced whereas, the coercivity decreased considerably. From UV–Vis diffuse reflection spectroscopy (DRS) measurements, the band gap energies of pure and doped α-Fe2O3 decreased from 2.01 to 1.94 eV respectively. Moreover, measurements of electrical properties showed that the dielectric permittivity decreased while the resistivity increased with increasing the gadolinium content. In addition, sulforhodamine B (SRB) test against oral epithelial cell lines showed low cytotoxicity of the particles. Finally, gadolinium doped hematite is introduced as a novel, environmentally benign material for potential applications in various fields including photocatalysis for water treatment, biosensor and as an antibacterial agent.

Tailoring the hyperthermia potential of magnetite nanoparticles via gadolinium ION substitution

Magnetic nanoparticles are one of the most promising candidates to achieve localization of heat in the region of cancerous tissue. Modified co-precipitation technique is carried out to synthesize GdxFe3-xO4 (where, x = 0.00 (IO), 0.04 (IOG02), 0.08 (IOG04), 0.12 (IOG06), 0.16 (IOG08), 0.20 (IOG10). A systematic characterization was performed to study the structural, morphological, elemental, and magnetic properties of the synthesized nanoparticles using X-Ray diffraction (XRD), Field emission scanning microscopy (FESEM), Energy Dispersive Spectroscopy (EDS), Vibrating sample magnetometer (VSM) respectively. The structural analysis revealed the single-phase crystalline nature of magnetite, with the co-existence of secondary phase hematite and goethite beyond x ≥ 0.16. The morphological analysis implied an increase in particle size due to Gd substitution with particle sizes ranging from 7 to 19 nm. Magnetic measurements revealed a magnetic transformation from superparamagnetic nature with magnetic coercivity and remanence to weak ferromagnetic nature upon an increase in the gadolinium content of magnetite. Further, hyperthermia studies showed that with increasing gadolinium concentration, the heating rate, specific absorption rate, and the intrinsic loss power of gadolinium substituted magnetites were increased. The increased specific absorption rate of gadolinium substituted magnetites with low HF factors makes them ideal for clinical hyperthermia applications.

Ultraviolet Radiation-Emitting Gd3+-Doped Sr2ZnSi2O7 Host Lattice Prepared by Sol–Gel Procedure and Evaluation of Gamma-Ray Exposure Parameters

Using the sol–gel process, a series of Sr2-xZnSi2O7:xGd (0.01 ≤ x≤0.11) samples was fabricated. Their crystal characteristics, surface morphologies, and spectral characteristics were analyzed using X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and photoluminescence (PL) spectroscopy. Upon 272-nm excitation, a prominent emission band appeared at 313 nm (6P7/2 → 8S7/2) in all the samples. The electron paramagnetic resonance (EPR) and PL analyses confirmed the presence of Gd3+ in the Sr2ZnSi2O7 structure, where the Gd3+ ions occupied distorted Sr2+ sites in the host lattice. Additionally, three photon interaction parameters, namely the mass attenuation coefficient, effective atomic number, and effective electron density, were calculated within the 1 keV–100 GeV photon energy range for all the samples. These photon interaction parameters varied widely over the studied energy range. Particularly, the shielding effectiveness increased with increasing gadolinium concentration. These interaction parameters will be very useful for shielding applications against gamma-rays.

Effect of lattice strain on structure, morphology and magneto-dielectric properties of spinel NiGdxFe2−xO4 ferrite nano-crystallites synthesized by sol-gel route

Nanocrystalline powders of Gadolinium (Gd3+) substituted nickel ferrite spinel (NiGdxFe2−xO4: x = 0.00, 0.025, 0.050, 0.075 and 0.1) samples were synthesized via sol-gel method. Nickel nitrate hexahydrate and Ferric nitrate hexahydrate were used as the precursors and rare earth Gadolinium nitrate hexahydrate [Gd(NO3)3·6H2O] was used as the dopant. The structural, morphological, magnetic and dielectric properties of the synthesized nanoparticles were examined by XRD, FTIR, HRSEM, EDX, TEM, VSM and dielectric studies. The Scherrer method and Williamson-Hall (W-H) method were used to evaluate the crystallite sizes and lattice strain. The crystallite size of NiGdxFe2−xO4 samples were found to decrease from 25 nm to 11 nm with increase in Gd3+ content. Lattice parameters decrease and lattice strain increases with the increase in Gd3+ content in the sample. HRSEM images showed the spherical morphology and uniform size distribution. The elemental composition analysis confirms the stoichiometric presence of expected elements in the samples. The crystallite size and the particle size calculated from the XRD analysis and HRTEM monographs indicate the correlation of the data obtained from both the measurements. Magnetic studies of the samples were performed using vibrating Sample Magnetometer, in which magnetizations (Ms) decrease with increase in Gd3+ concentration from 36.51 emu/gm to 19.69 emu/gm. As the gadolinium content was gradually increased, coercivity and remnant magnetization were also decreased. Magnetic anisotropy of nickel ferrite was also found to decrease with increasing gadolinium content. The saturation magnetization values were achieved by using the “Law of Approach (LA) to Saturation magnetization” technique. Specific correlation between magnetic interaction and lattice strain was observed in Gd3+ substituted nickel ferrite. Dielectric parameters such as dielectric constant and dielectric loss of the prepared samples decrease with increase of applied frequency and increasing of Gd3+ doping concentration.

A Study of the Thermovoltaic Effect in Heterostructures Based on Sm1–xGd x S Solid Solutions

The influence of doping of samarium monosulfide with gadolinium has been investigated. Experiments have been carried out in the temperature range of 300–450 K. A decrease in the effect value with increasing gadolinium content in the Sm1–xGdxS heterostructure with x ranged from 0 to 0.13 has been found and explained. Formulas for calculating the output signal in dependence of the doping value have been derived.

Structure, densification and electrical properties of Gd3+ and Cu2+ co-doped ceria solid electrolytes for SOFC applications: Effects of Gd2O3 content

Ceria-based solid electrolytes exhibit superior electrical conductivity compared to traditional yttria-stabilized zirconia ceramics. However, they require high sintering temperatures to achieve full densification. Transition metal oxides exhibiting low melting points, such as CuO, have been used as additives to lower the sintering temperature of these materials. In this context, the present work is focused on the evaluation of the effects of gadolinium oxide (Gd2O3) content on the structure, densification and electrical properties of ceria co-doped with CuO. Nominal compositions of Ce0.99−xGdxCu0.01O2-δ (0 ≤ x ≤ 0.3) were synthesized by the polymeric precursor method. The precursor powders were characterized by simultaneous thermogravimetry and differential thermal analysis (TG/DTA) and the calcined powders were studied by X-ray diffraction (XRD) and Rietveld refinement to obtain crystallographic parameters. The sinterability of green bodies was evaluated by dilatometry up to 1200°C. The relative density was determined in samples sintered between 950 and 1050°C and the microstructural characterization was performed by scanning electron microscopy (SEM). The electrical properties were investigated by impedance spectroscopy (IS). The XRD results confirms the formation of a cubic fluorite type structure in the entire composition range. The lattice parameters obtained by Rietveld refinement showed a reduction in the crystallite size with increasing gadolinium content. Densification was improved with increasing Gd-content up to x = 0.15. The electrical conductivity was enhanced by gadolinium addition, reaching a maximum of 7.81mScm−1 at 600°C for the composition x = 0.15 sintered at a temperature as low as 1050°C.

Enhanced quantitative susceptibility mapping (QSM) using real-time field control.

To assess the potential of a real-time field-control (FC) system for mitigating effects of spatiotemporal field fluctuations in quantitative susceptibility mapping (QSM) at 7 T. Magnitude, phase, and QSM images of phantoms and healthy volunteers were acquired under standard conditions and under induced field perturbation (FP) (phantoms: periodic water-bottle displacement; volunteers: deep breathing and forearm movement) with and without FC, which continuously detects and minimizes magnetic-field variations. Field control successfully eliminated FP-induced impairment of phantom image quality and deviations from a linear susceptibility increase for increasing gadolinium concentration in a Gd dilution series (y = 320x - 0.60, R2 = 0.93 for the scan with FP and FC versus y = 259x - 0.54, R2 = 0.78 for the scan with FP and no FC (slope literature value: 326 ppm L/mol)). Similarly, in volunteers, FC allowed a recovery of a FP-induced loss of identifiable brain structures and reduced the relative change of mean susceptibilities and standard deviations (93 ± 53% to 34 ± 46%) in all regions of interests with respect to the reference scan. Real-time FC improved the delineation of brain structures and the match of susceptibility values with reference values obtained without FP. Magn Reson Med 79:770-778, 2018. © 2017 International Society for Magnetic Resonance in Medicine.

Dose Distribution and Dose Enhancement by Using Gadolinium Nanoparticles Implant in Brain Tumor in Stereotactic Brachytherapy

BackgroundThe photoelectric and pair production processes increase when high-energy photons interact with materials with high atomic number Z. The energy loss results in a dose enhancement at the target implanted with these materials. This will lead to a higher active dose to be delivered to tumor, while sparing healthy tissues around the target volume. Objective and methodThe objective of this work was to compute the radial dose enhancement, using GEANT4 based Monte Carlo simulations, at and near a 1×1×1cm3 brain tumor implanted with different concentrations of gadolinium nanoparticles when using 192Ir, 137Cs and 60Co, brachytherapy sources with parallel beam geometry. ResultsOur outcomes show a dose enhancement factor of 1.45 for a concentration of 70mg of gadolinium in the tumor when irradiated with 0.38MeV γ-photon from 192Ir source. It was also observed that this dose enhancement increased with increasing gadolinium concentration in the target and with photon energy. ConclusionGadolinium nanoparticles are groundbreaking agents with strong advantageous potential in cancer radiotherapy due to the fact that they enhance the radiation dose within the tumor.

Luminescence quenching and scintillation response in the Ce3+ doped GdxY3−xAl5O12 (x = 0.75, 1, 1.25, 1.5, 1.75, 2) single crystals

The luminescence and scintillation properties of the gadolinium yttrium aluminium garnets, (Gd,Y)3Al5O12 doped with Ce3+ are investigated as a function of the Gd/Y ratio with the aim of an improved understanding of the luminescence quenching, energy transfer and phase stability in these materials. An increase of both crystal field strength and instability of the garnet phase with increasing content of Gd3+ is observed. The instability of the garnet phase results in an appearance of the perovskite phase inclusions incorporated into the garnet phase. The luminescence features of Ce3+ in the perovskite phase inclusions and in the main garnet phase are studied separately. The thermal quenching of the 5 d → 4f emission of Ce3+ in the latter phase is determined by temperature dependence of the photoluminescence decay time. The results show that the onset of the thermal quenching is moved to lower temperatures with increasing gadolinium content. The measurements of temperature dependence of delayed radiative recombination do not reveal a clear evidence that the thermal quenching is caused by thermally induced ionization of the Ce3+ 5d1 excited state. Therefore, the main mechanism responsible for the luminescence quenching is due to the non-radiative relaxation from 5d1 excited state to 4f ground state of Ce3+. The energy transfer processes between Gd3+ and Ce3+ as well as between perovskite and garnet phases are evidenced by the photoluminescence excitation and emission spectra as well as decay kinetic measurements. Thermally stimulated luminescence (TSL) studies in the temperature range 77–497 K and scintillation decays under γ excitation complete the material characterization.

Phase separation and magnetocaloric effect in Pr0.5−xGdx Sr0.5MnO3 system

The magnetic properties and the magnetocaloric effect have been studied in Pr0.5−xGdxSr0.5MnO3 (x = 0, 0.05 and 0.1) manganites prepared by the solid state reaction method. Magnetic measurements versus temperature in an applied magnetic field of 0.05 T show that the all samples exhibit a paramagnetic to ferromagnetic transition when temperature decreases. The x = 0.1 sample shows a clear transition, from the ferromagnetic state to the antiferromagnetic one at TN = 125 K. The Curie temperature decreases gradually with increasing gadolinium content. The absolute values of the maximum of magnetic entropy change |ΔSM| for an applied magnetic field of 2 T are equal to1.26, 1.25 and 1.02 J kg−1 K−1 for x = 0, 0.05 and 0.1, respectively. The decrease of |ΔSM| with Gd doping can be attributed to the enhancement of phase separation phenomenon. The magnetic entropy curves follow the universal law corresponding to the second-ordered paramagnetic-ferromagnetic transition.

μ-Raman and infrared reflectance spectroscopy characterization of (Lu1−xGdx)2SiO5 solid solution single crystals doped with Dy3+ or Sm3+

Single crystals of Lu2SiO5:5 at% Dy3+ - LSO:5Dy,(Lu0.6Gd0.4)2SiO5:4 at% Dy3+ - 60LGSO:4Dy and (Lu0.4Gd0.6)2SiO5:5 at% Sm3+ - 40LGSO:5Sm were obtained by the Czochralski method. It was found that the crystallographic structure of investigated crystals is isostructural with Lu2SiO5 which crystallizes in monoclinic system within a space group C2/c. Detailed spectroscopic analysis in a wide spectral region was carried out for these three solid solution crystals using two complementary techniques polarized Raman and infrared reflectance spectroscopy. Additional interesting information for the low-wavenumber range phonons were obtained using an NExT filter. The red shift of almost all modes with increasing gadolinium content was observed. It results from an increase in the lattice constants. The change in the splitting of the most intense symmetric stretching mode ν1 assigned to vibrations of SiO4 tetrahedra was observed with increasing gadolinium content. The spectral distance between the two components of this mode decreased from 23 cm−1 for LSO:5Dy through 20 cm−1 for 60LGSO:4Dy to 14 cm−1 for 40LGSO:5Sm. Analysis of vibrational spectra provides the information about structural changes and increase in crystal structure disorder with increasing gadolinium content. Increasing disorder observed in vibrational spectra indicates the possibility of substantial broadening of spectral lines of optically active ions in luminescence spectra.

Electron Magnetic Resonance of Diluted Solid Solutions of Gd3+ in BaTiO3

Electron magnetic resonance (EMR) spectra of gadolinium-doped barium titanate (BaTiO3) have been studied at room temperature for gadolinium concentrations between 0.20 and 2.00 mol%. The results suggest that the Gd3+ ions occupy substitutional sites, replacing the Ba2+ ion, that the electron magnetic resonance linewidth increases with increasing gadolinium concentration, and that the range of the exchange interaction between Gd3+ ions is about 0.98 nm, of the same order as that of the same ion in other host lattices, such as strontium titanate (SrTiO3), strontia (SrO), quicklime (CaO), magnesia (MgO) and zircon (ZrSiO4). The fact that the electron magnetic resonance linewidth of the Gd3+ ion increases, regularly and predictably, with Gd concentration, shows that the Gd3+ ion can be used as a probe to study, rapidly and non-destructively, the crystallinity and degradation of BaTiO3.

Electron magnetic resonance of diluted solid solutions of Gd 3+ in SrTiO 3

Electron magnetic resonance (EMR) spectra of gadolinium-doped strontium titanate (SrTiO 3) have been studied at room temperature for gadolinium concentrations between 0.20 and 1.20 mol%. The results suggest that the Gd 3+ ions occupy substitutional sites, replacing the Sr 2+ ion, that the electron magnetic resonance linewidth increases with increasing gadolinium concentration and that the range of the exchange interaction between Gd 3+ ions is about 0.96 nm, of the same order as that of the same ion in other host lattices, such as ceria (CeO 2), quicklime (CaO), strontia (SrO) and zircon (ZrSiO 4). The fact that the electron magnetic resonance linewidth of the Gd 3+ ion increases, regularly and predictably, with Gd concentration, shows that the Gd 3+ ion can be used as a probe to study, rapidly and non-destructively, the crystallinity and degradation of SrTiO 3.

Solid-state synthesis and characterization of new cadmium and rare-earth metal molybdato-tungstates Cd 0.25RE0.50(MoO 4) 0.25(WO 4) 0.75 ( RE = Pr, Nd, Sm–Dy)

New cadmium and rare-earth double molybdato-tungstates Cd 0.25 RE 0.50(MoO 4) 0.25(WO 4) 0.75 ( RE = Pr, Nd, Sm–Dy) were prepared by the solid-state reaction technique from CdMoO 4 and adequate RE 2(WO 4) 3. The obtained compounds crystallized in the scheelite-type structure and showed solubility in CdMoO 4 forming Cd x Gd 2 − 2 x (MoO 4) x (WO 4) 3 − 3 x solid solutions for 0.50 < x < 1.00. All the obtained phases were characterized by XRD, DTA-TG, IR and EPR methods. The EPR measurements of gadolinium containing samples confirmed that Gd 3+ ions were located at octahedral positions. With the increasing gadolinium content the exchange and dipole–dipole interactions led to a totally antiferromagnetic type of interaction in the Gd 3+ chains network.

Effect of Gd and Yb co-doping on structure and electrical conductivity of the Sm 2Zr 2O 7 pyrochlore

SmYb 1− x Gd x Zr 2O 7 (0 ≤ x ≤ 1.0) ceramics were pressureless-sintered at 1973 K for 10 h in air. The relative density, structure and electrical conductivity of SmYb 1− x Gd x Zr 2O 7 ceramics were investigated by the Archimedes method, X-ray diffraction, scanning electron microscopy and impedance spectroscopy measurements. SmYb 1− x Gd x Zr 2O 7 (0 ≤ x ≤ 0.5) ceramics exhibit a defect fluorite-type structure, while SmYb 1− x Gd x Zr 2O 7 (0.7 ≤ x ≤ 1.0) ceramics have a pyrochlore-type structure. The measured values of the electrical conductivities obey the Arrhenius relation. The grain conductivity of each composition in SmYb 1− x Gd x Zr 2O 7 ceramics increases with increasing temperature from 723 to 1173 K. The grain conductivity of SmYb 1− x Gd x Zr 2O 7 ceramics gradually increases with increasing gadolinium content at identical temperature levels. An increase of about one order of magnitude in grain conductivity is found at all temperature levels when the gadolinium content increases from 0.5 to 0.7. SmYb 1− x Gd x Zr 2O 7 ceramics are oxide-ion conductors in the oxygen partial pressure range of 1.0 × 10 −4 to 1.0 atm at all test temperature levels. The highest grain conductivity value obtained in this work is 2.69 × 10 −2 S cm −1 at 1173 K for SmGdZr 2O 7 ceramic.

Influence of gadolinium concentration on the EMR spectrum of Gd3+ in zircon

Abstract Electron magnetic resonance (EMR) spectra of gadolinium-doped zircon (ZrSiO 4 ) powders have been studied at room temperature for gadolinium concentrations between 0.20 and 1.0 mol%. The results suggest that Gd 3+ ions occupy substitutional sites in the zircon lattice, that the electron magnetic resonance linewidth increases with increasing gadolinium concentration and that the range of the exchange interaction between Gd 3+ ions is about 1.17 nm, larger than that of the same ion in other host lattices, such as ceria (CeO 2 ), strontium oxide (SrO) and calcium oxide (CaO). The fact that the electron magnetic resonance linewidth of the Gd 3+ ion in polycrystalline zircon increases, regularly and predictably, with Gd concentration, shows that the Gd 3+ ion can be used as a probe to study, rapidly and non-destructively, the crystallinity and degradation of ZrSiO 4 .

Structure and Thermal Expansion Behavior of Dy&lt;sub&gt;2-x&lt;/sub&gt;Gd&lt;sub&gt;x&lt;/sub&gt;Mo&lt;sub&gt;4&lt;/sub&gt;O&lt;sub&gt;15&lt;/sub&gt; Solid Solution

A new series of solid solutions Dy2-xGdxMo4O15 (x = 0.0-0.9) were prepared. These compounds all crystallize in monoclinic structure with space group P21/c. The lattice parameters a, b, c and unit cell volumes V increase almost linearly with increasing gadolinium content. The intrinsic thermal expansion coefficients of Dy2-xGdxMo4O15 (x = 0.0 and 0.25) were obtained in the temperature range of 25 to 500°C with high-temperature X-ray diffraction. The correlation between thermal expansion and crystal structure was discussed.

Misregistration artifacts in image‐derived arterial input function in non‐echo‐planar imaging‐based dynamic contrast‐enhanced MRI

To characterize misregistration artifact in arterial input function (AIF) pixels in dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) using a two-dimensional non-echo-planar imaging (EPI)-based gradient-recalled echo (GRE) sequence. Dynamic gadopentetate-enhanced MRI was acquired in the rat using a semikeyhole acquisition scheme. The AIF was obtained from abdominal aorta pixels. Different sliding-window reconstruction techniques were applied to determine which lines in a series of the semikeyhole acquisition were associated with the misregistration artifacts. The misregistration along the phase-encoding direction arose when k-space lines were acquired during the rise-time of the aortic gadolinium concentration. The maximum blood concentration of gadolinium estimated from the phase shift calculation agreed with that estimated from dosage. AIF misregistration results from a phase shift due to increasing gadolinium concentration in the aorta, and may need to be considered in small animal DCE-MRI studies with a high rate of rise in the AIF in high-field MR applications.

Electronic structure and magnetic properties ofGdxLa1−xNi5 system

Magnetic measurements were performed onGdxLa1−xNi5 compounds in the temperature range 1.7–300 K and fields up to 90 kOe.There is a transition from a spin fluctuation behaviour, characteristic forLaNi5,to a ferrimagnetictype ordering for x≥0.2. The critical field for appearance of induced Ni moment was estimated. Then, the nickel moments,at 1.7 K, increase linearly with the exchange field. Band structure calculations were performed onRNi5 and GdxLa1−xNi5 systems. The Gd 5d band polarization is due to both local 4f–5d exchangeand 5d–3d short range interactions with neighbouring atoms. There arealso 5d–5d interactions through orbitals having lobes oriented along thec-axis. The differences between magnetic moments at 2c and 3g sites, obtainedfrom band structure calculations, were correlated with their local environments.The mean effective nickel moments decrease when increasing gadolinium content,an opposite behaviour to that evidenced for ordered Ni moments at 1.7 K. Thisbehaviour was attributed to gradual quenching of spin fluctuations by internal field.