Composition Gd Research Articles

Magnetic properties of GdFeCo thin films tailored by sputtering conditions

The unique properties of ferrimagnets including easy detection of their dynamic and static states, strong resistance to external disturbances, and rapid dynamic characteristics, have made them attractive in the spintronics community. Our study focuses on the engineering of these magnetic properties of ferrimagnets, particularly employing a GdFeCo alloy, a prominent ferrimagnetic material, by utilizing magnetron sputtering. A series of GdFeCo films are fabricated by altering their thicknesses and working pressure during the sputtering process. Our experimental results reveal that these sputtering parameters significantly influence a Gd composition within the films, which in turn affects critical properties of ferrimagnets such as magnetic anisotropy, and magnetic moment compensation temperature. By precisely controlling these sputtering parameters, we successfully tailored the magnetic properties of the GdFeCo thin films with desired properties, offering new possibilities for the creation of sophisticated magnetic materials tailored to specific technological needs.

Influence on the effect of Gd rare earth doped WO3 nanoparticles for enhanced photocatalytic and antibacterial activities: A nanoplate like morphology

Optimizing the photocatalytic antibacterial properties of nanomaterials by defect engineering is becoming a significant tool. The synthesis and characterization of Gd- doped tungsten oxide (Gd:WO3) nanoparticles for potential applications in wastewater treatment and antibacterial activity. Synthesis of the Gd:WO3 nanoparticles were prepared using the co-precipitation method, known for its simplicity and cost-effectiveness in producing nanomaterials. Samples were characterization by XRD confirmed the monoclinic crystal system of all samples and the incorporation of Gd ions into the WO3 lattice. SEM and TEM revealed a nanoplate-shaped morphology of the synthesized nanostructures. EDS confirmed the composition of Gd:WO3. FT-IR verified the presence of functional groups. XPS investigated the effect of Gd doping on the valence states of Gd:WO3, revealing the location of Gd ions within the WO3 lattice. UV-Vis showed increased absorption in the visible region and a decrease in the band gap with increasing Gd concentration up to 5 wt%, indicating potential photocatalytic properties. The nanoparticles demonstrated significant photocatalytic activity, achieving a 98 % degradation of methylene blue (MB) dye under visible light exposure. Among them, the Gd (5 wt%) nanoparticles exhibited the highest photocatalytic performance within 120 min. Additionally, these Gd (5 wt%) nanoparticles showed the greatest antibacterial effectiveness against Staphylococcus aureus, with an inhibition zone of 20 mm. Moreover, the study demonstrates the potential of Gd-doped tungsten oxide nanoparticles as efficient and environmentally friendly materials for wastewater treatment and antibacterial applications.

Inclusion Complex of Gd(III) with β-Cyclodextrin and L-Tryptophan

An inclusion complex of gadolinium(III) with L-tryptophan (Trp) and β-cyclodextrin (β-CD) with the composition Gd(Trp)3Cl3∙3β-CD∙nH2O was synthesized. It was established that the complex is formed due to the entry of the aromatic part of the L-Trp molecule into the β-CD cavity, and the Gd3+ ions are located in the outer sphere.

A Study on Fine-Tuning the Optical Energy Band Gap and Various Optical Parameters with the Impact of Gadolinium Composition in NGFO Ferrite Nanoparticles

In the present work, gadolinium-doped nickel ferrite nanoparticles with the chemical composition NiFe2−xGdxO4 (X = 0.00, 0.05, 0.10, 0.15, 0.20, and 0.25) have been prepared by the sol-gel auto-combustion method and calcinated at 700 ∘C. The spinel ferrite phase formation was confirmed with the XRD graphs. In all the samples, the typical absorbance peak was observed in between 250–300 nm. Tauc plots were used to calculate the optical energy band gap, found in the range of 4.033–4.144 eV, and it was also calculated using x-ray density to be in the range of 3.690–4.300 eV. Both of them were observed in good agreement with each other, and we conclude that the Gd composition could finely tune the optical energy band gap. The impact of Gd composition was clearly observed on optical parameters. The refractive index, reflectivity, absorption coefficient, optical dielectric constant, and dielectric susceptibility have shown the increasing tendency from 2.1140 to 2.2325, 12.80 to 14.53%, 5.4380 to 6.3032 cm−1, 3.4690 to 3.9840 and 0.2760 to 0.3170, respectively, whereas the transmission coefficient decreased from 0.7730 to 0.7461.

Effect of Gadolinium Content on Magnetic and Structural Characteristics of NFGO Nano-Particles

Sol gel auto-combustion was used to create gadolinium doped nickel ferrite nano-particles, which have chemical composition NiFe2‑xGdxO4 (x = 0.00, 0.010, 0.15, 0.20 & 0.25). The investigation focused on how the composition of Gd+3 affected the magnetic properties and structural parameters. Magnetic properties were investigated using VSM technique, structural properties were determined using XRD and SEM techniques. XRD graphs verified the establishment of the spinel ferrite phase. With an increase in Gd composition, the crystallite size and lattice parameter increased from 21.0288 to 27.04125 nm and 8.3325 to 8.3367Å, respectively. It was also evident how the composition of Gd+3 affected the estimation of bond-angles and lengths in tetrahedral and octahedral structures. SEM micrographs showed that all of the grains had a small amount of agglomeration and that all of the synthesized compositions were homogenous. The range of 140.5–176.2 nm was found to be the average grain size. Using VSM at 300K, magnetic parameters like coercivity, residual magnetization, and saturation magnetization were computed. Until the composition was 0.20, the saturation magnetization and residual magnetization dropped from 30.28 emu/g to 15.35 emu/g and 5.07 emu/g to 3.65 emu/g, respectively. After that, they increased to 34.40 emu/g and 6.52 emu/g, respectively. Until composition 0.20, coercivity was raised from 154 to 261 Oe; after that, it was lowered to 233 Oe.

Sm and Gd Isotopic Shifts in Eucrites and Implications for Their Cosmic-Ray Exposure History

The isotopic compositions of Sm and Gd in eight eucrites—five from a desert, Dar al Gani (DaG) 380, DaG 391, DaG 411, DaG 443, and DaG 480, and three from nondesert areas, Juvinas, Millibillillie, and Stannern—were determined to understand the cosmic-ray exposure (CRE) history for each meteorite from the isotopic shifts of 149Sm–150Sm and 157Gd–158Gd caused by the neutron capture reactions induced by cosmic-ray irradiation. Seven of the eight samples, excepting DaG 443, show readily detectable isotopic shifts of Sm and Gd corresponding to neutron fluences in the range of (0.28–2.38) × 1015 neutrons cm−2. The degrees of Sm isotopic shifts for six of these seven eucrites can be consistently explained by the CRE age histogram of eucrites obtained in previous studies. Exceptionally, DaG 480 shows larger isotopic shifts of Sm than those expected from the CRE age histogram, suggesting a multiple-irradiation history, including irradiation on the parent body. However, there is no clear difference in the CRE conditions between DaG 480 and other eucrites from the parameter ε Sm/ε Gd to identify the difference in the thermalization degree of neutrons in association with the CRE conditions.

Phase equilibria and microstructure development in Mg-rich Mg-Gd-Sr alloys: Experiments and CALPHAD assessment

Mg-Sr alloys are promising to fabricate orthopedic implants. The alloying of rare earth elements such as Gd may improve the comprehensive mechanical properties of Mg-Sr alloys. The information on the phase diagram and the microstructure development are required to design chemical composition and microstructure of Gd alloyed Mg-Sr alloys. The phase equilibria and the microstructure development in Mg-rich Mg-Gd-Sr alloys (Gd, Sr < 30 at. %) are experimentally investigated via phase identification, chemical analysis, and microstructure observation with respect to the annealed ternary alloys. The onset temperatures of liquid formation are measured by differential scanning calorimetry. A thermodynamic database of the Mg-rich Mg–Gd–Sr ternary system is developed for the first time via CALPHAD (CALculation of PHAse Diagram) approach assisted by First-Principles calculations. The thermodynamic calculations with the developed database enable a well reproduction of the experimental findings and the physical-metallurgical understanding of the microstructure formation in solidification and annealing.

Metastable phase separation and duplex metallic glass formation of liquid Zr&lt;sub&gt;35&lt;/sub&gt;Al&lt;sub&gt;23&lt;/sub&gt;Ni&lt;sub&gt;22&lt;/sub&gt;Gd&lt;sub&gt;20&lt;/sub&gt; alloy

Duplex metallic glass with two amorphous phases has been extensively investigated for desirable strength and plasticity. In this paper, the metastable phase separation and dual amorphous phase formation of liquid Zr&lt;sub&gt;35&lt;/sub&gt;Al&lt;sub&gt;23&lt;/sub&gt;Ni&lt;sub&gt;22&lt;/sub&gt;Gd&lt;sub&gt;20&lt;/sub&gt; alloy under substantial undercooling condition and rapid cooling condition are studied by drop tube technology. The equilibrium solidification structure consists of three crystalline phases, while the critical undercooling temperature of metastable phase separation is determined to be 516 K (0.37&lt;i&gt;T&lt;/i&gt;&lt;sub&gt;L&lt;/sub&gt;). The separated Zr-rich liquid phase undergoes amorphous transition and becomes amorphous AM-Zr phase with the composition of Zr&lt;sub&gt;45&lt;/sub&gt;Ni&lt;sub&gt;23&lt;/sub&gt;Al&lt;sub&gt;23&lt;/sub&gt;Gd&lt;sub&gt;9&lt;/sub&gt; when alloy undercooling is increased to 624 K (0.45&lt;i&gt;T&lt;/i&gt;&lt;sub&gt;L&lt;/sub&gt;). After that, the Gd-rich liquid phase forms amorphous AM-Gd phase with the composition of Gd&lt;sub&gt;39&lt;/sub&gt;Al&lt;sub&gt;22&lt;/sub&gt;Ni&lt;sub&gt;20&lt;/sub&gt;Zr&lt;sub&gt;19&lt;/sub&gt; at larger undercooling of 714 K (0.52&lt;i&gt;T&lt;/i&gt;&lt;sub&gt;L&lt;/sub&gt;). With the increase of liquid undercooling and cooling rate, the kinetic mechanism of metastable phase separation changes from nucleation and growth type to spinodal decomposition type, and consequently the microstructure of dual amorphous phases transforms from a spherical morphology to a reticular structure. The average hardness and Young’s modulus, which are influenced by free volume, phase volume fraction and structure of dual amorphous phases, exhibit a complex variation of first increasing and then decreasing with the decrease of alloy droplet size. The formation of dual amorphous phases is in favor of the energy dissipation and the generation of multiple shear bands during mechanical compression, which improves the plasticity for this kind of amorphous alloy.

Spatially nonuniform oscillations in ferrimagnets based on an atomistic model

The ferrimagnets, such as GdxFeCo(1-x), can produce ultrafast magnetic switching and oscillation due to the strong exchange field. The two-sublattices macrospin model has been widely used to explain the experimental results. However, it fails in describing the spatial nonuniform magnetic dynamics which gives rises to many important phenomenons such as the domain walls and skyrmions. Here we develop the two-dimensional atomistic model and provide a torque analysis method to study the ferrimagnetic oscillation. Under the spin-transfer torque, the magnetization oscillates in the exchange mode or the flipped exchange mode. When the Gd composition is increased, the exchange mode firstly disappears, and then appears again as the magnetization compensation point is reached. We show that these results can only be explained by analyzing the spatial distribution of magnetization and effective fields. In particular, when the sample is small, a spatial nonuniform oscillation is also observed in the square film. Our work reveals the importance of spatial magnetic distributions in understanding the ferrimagnetic dynamics. The method developed in this paper provides an important tool to gain a deeper understanding of ferrimagnets and antiferromagnets. The observed ultrafast dynamics can also stimulate the development of THz oscillators.

Characterization of different meat flavor compounds in Guangdong small-ear spotted and Yorkshire pork using two-dimensional gas chromatography–time-of-flight mass spectrometry and multi-omics

In China, indigenous pigs are popular due to their excellent meat quality and unique flavor. In this study, the unique flavor was investigated using Guangdong small-ear spotted pig (GD) and their hybrid progeny, which produced high-end pork in the Chinese market. Two-dimensional gas chromatography-time-of-flight mass spectrometry (GC × GC-TOF MS) was used to analyze and quantify volatile organic compounds (VOCs) in the two pork types for identifying the unique flavor of these very popular pigs. The flavor is imparted by alkanes, aldehydes, ketones, and ethers. Flavor imparting compounds mainly include methyl isobutyl ketone, octane, pentane, and 3-ethyl-2, 2-dimethylheptane. High levels of volatilization of such compounds generated ethereal, acetonic, sweet, and green odors in the pork of GD. Hybrid offspring of Chinese and Western pig breeds can also inherit such special aromas, which are sometimes even more intense, with increased meat yield. Multi-omics analysis of the transcriptome and metabolome showed that AMD1 (Adenosylmethionine Decarboxylase 1) affects the p-cresol content by regulating the polyamine pathway, affecting the unique flavor of GD. This study revealed the unique flavor composition of GD, analyzed the advantages of species hybridization, and thus, provides a new direction and theoretical basis for pork quality improvement.

Superior ferromagnetic and electrical properties: High purity multiferroic Bi0.98M0.02FeO3 (M = La, Pr, Gd) compositions

Enhanced resistivity and full wide ranging-saturated ferromagnetic loop with high saturation magnetization were originated in light Gd-modified BiFeO3. In this study, high purity BiFeO3, Bi0.98La0.02FeO3, Bi0.98Pr0.02FeO3 and Bi0.98Gd0.02FeO3 compositions have been synthesized via facile glycine-autocombustion technique. Crystalline rhombohedral lattice corresponding to BiFeO3 single phase was formed in all samples. Reengineering of band gap structure and lattice dimensions alongside the XRD peaks shifts verified the replacement of La3+, Pr3+/4+ and Gd3+ ions for Bi3+-sites into BiFeO3. The SEM micrographs of Bi0.98La0.02FeO3 demonstrated the formation of network of porous structure with a root like-shape while particles with chip-wavy shape were seen for Bi0.98Pr0.02FeO3. The micrograph of Bi0.98Gd0.02FeO3 sample displays highly porous arrangements with a spongy shape. The BET surface area, pore volume and pore size of pure BiFeO3 were determined to be 3.1478 m2/g, 0.1260 cm3/g and 9.6 nm, respectively. The measurements display that the surface area and pore volume of BiFeO3 were increased due to Gd doping to reach to 7.3044 m2/g and 0.8561 cm3/g, respectively. Optically, La, Pr and Gd doping engineered the energy gap width of BiFeO3 (2.09 eV), resulting in band gap of 2.16, 2.14, and 2.1 eV, respectively. Based on band gap, high refractive index (n) values greater than 2.5 were detected for all samples which are applicable values for many optical applications. La, Pr and Gd ions have a positive effect on reducing the energy dissipation-dielectric loss factor and also enhancing the resistivity of BiFeO3. The M−H loops indicated that the magnetic property of 2 wt% Gd-modified BiFeO3 was highly enhanced in comparison to that of BiFeO3. Bi0.98Gd0.02FeO3 composition displayed superior values of saturation magnetization of 2.064 emu/g, remanent magnetization (Mr) of 0.246 emu/g and coercivity (Hc) of 125.8 Oe.

Thermal impact on ultrafast helicity independent all-optical switching of GdxCo100-x

Ultrafast all-optical switching by single femtosecond laser pulse has recently been considered as one of the most potential technologies for the application on high-speed and energy efficient memory device. Here, to ensure such a sophisticated technology to be applicable to more complex environments, we report the dependence of all-optical switching of the ferrimagnet, GdCo, on the ambient temperature. Through heating the GdCo film up to 380 K, we demonstrate the distinct magnetic behaviours and the critical laser fluences of all-optical switching under different composition of Gd. It is found that the thermal stability for AOS will be significantly improved when there are more rare-earth elements, Gd in GdCo. This work provides a deep insight into the thermal effect on helicity independent all-optical switching and will optimize the application of ultrafast technology on the spintronic devices and magnetic memories.

DFT, MD simulations and experimental analysis of adsorptive complexation and isotope separation of gadolinium ion with macrocyclic crown ether embedded polymeric resin

Di-benzo-18-crown-6 ether (DB18C6) functionalized polymethyl acrylic acid (PMA) resin was synthesized after screening by employing density functional theory (DFT) and molecular dynamics (MD) simulations for the enrichment of gadolinium isotopes, Gd-155 and Gd-157. Batch adsorption and column chromatography studies were performed at various pH, gadolinium ion concentration and temperatures to check its efficacy and validation of theoretical approach. The adsorption capacity of gadolinium ion with the PMADB18C6 resin was found to be quite modest with a value of 1.128 mg/g. Both MD simulations and adsorption experiments confirm the Temkin type of adsorption isotherm. The positive entropy change along with the positive enthalpy change indicates that sorption of the Gd3+ ion with PMADB18C6 is entropy driven process. From the chromatography experiments, the lighter isotope (Gd-155) is seen to be depleted in the breakthrough volume samples which specify that the resin phase is depleted with heavier isotope (e.g Gd-160) contrast to natural Gd composition. The separation coefficient (ε) for Gd155/158, Gd156/158, Gd157/158, Gd155/160 and Gd157/160 isotopic pairs were found to be 1.67 × 10−3, 2.65 × 10−3, 5.40 × 10−4, 3.18 × 10−3 and 1.87 × 10−3 respectively. The experimental isotopic separation factor corroborates the DFT findings. Further, both DFT and MD simulations confirm the experimentally observed endothermic complexation of Gd3+ ion with PMADB18C6 resin. The present findings employing combined DFT, MD simulations and experimental approaches are expected to benefit in the fundamental understanding of molecular complexation based isotope separation and design and development of future gadolinium isotopic enrichment technologies using chemical exchange methods.

Compositionally Disordered Doped with Cerium Crystalline Garnet Type Materials for Brighter and Faster Scintillations

Ce-doped tetracationic garnets (Gd, M)3Al2Ga3O12(M = Y, Lu) form a family of new multipurpose promising scintillation materials. The aim of this work was to evaluate the scintillation yield in the materials of quaternary garnets activated by cerium ions with partial isovalent substitution of the matrix-forming gadolinium ions by yttrium or lutetium ions.Materials were obtained in the form of polycrystalline ceramic samples, and the best results were shown by samples obtained from the raw materials produced by the coprecipitation method. It was found that ceramics obtained from coprecipitated raw materials ensure a uniform distribution of activator ions in the multi-cationic matrices, which enables the high light yield and fast scintillation kinetics of the scintillation. It was demonstrated that the superstoichiometric content of lutetium/gadolinium in the material is an effective method to suppress phosphorescence accompanied scintillation. For ceramics with the composition (Gd, Lu)3Al2Ga3O12 , a scintillation yield of more than 50.000 ph/MeV was achieved. The scintillation kinetics was measured to be close to the kinetics with a decay constant of 50 ns.In terms of the set of the parameters, the developed scintillation materials are close to the recently developed alkali halide materials LaBr3:Ce, GdBr3:Ce. Moreover, they have high mechanical hardness, are characterized by the absence of hygroscopicity, and are better adapted to the manufacture of pixel detectors used in modern devices for medical diagnostics.

Robust finite-temperature magnetization dynamics in ferrimagnetic Gdx(FeCo)1−x (x = 0 ∼ 0.44) nanospheres across angular-momentum and magnetization compensation points: An atomistic model simulation

We explored robust magnetization dynamics in ferrimagnetic Gdx(FeCo)1−x nanospheres of Gd compositions ranging from x = 0 to 0.44 at finite T = 0 – 1200 K temperatures using two-sublattice atomistic simulations based on the stochastic Landau-Lifshitz-Gilbert equation. It was found that the magnetization compensation and angular-momentum compensation temperatures vary remarkably with x and that the former temperature is always lower than the latter. Also, it was found that neither compensation temperature exists below a specific Gd composition of x = 0.22, but above which, both exist and increase with x. The ferromagnetic resonance (FMR) frequency remarkably increases at the angular momentum compensation composition, whereas the FMR frequency does not reach zero at the magnetization compensation composition. The significant difference in the FMR frequency between the two characteristic compensation points is ascribed to the contrasting effective gyromagnetic ratios of Gd and FeCo. Our present atomistic simulation study well reproduced the earlier experimental observations of such dynamic behaviors at both the angular-momentum and magnetization compensation points, which observations cannot be explained by the existing Kittel and Wangsness models. This work provides a better understanding of robust dynamic behaviors of ferrimagnetic nanospheres as functions of temperature and constituent sublattice composition, especially at and near the characteristic compensation points.

Improvement of Pinning Properties by Refining Gd2O3 Particles Trapped in GdBa2Cu3O7-δ Coated Conductors Fabricated by the RCE-DR Process

In order to improve in-field <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">J</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> values of GdBCO CCs fabricated by the reactive co-evaporation by deposition and reaction (RCE-DR) process with the nominal composition of Gd:Ba:Cu = 1:1:2.5, the Gd <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> particles trapped in the GdBCO superconducting matrix were refined by controlling the nucleation and growth temperature of Gd <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> in the liquid phase before the growth of GdBCO film at the same growth conditions of 860 °C in 150 mTorr oxygen pressure. With decreasing the growth temperature of Gd <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> from 860 to 820 °C in the oxygen pressure of 30 mTorr, the average particle size of Gd <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> was monotonously decreased from 125 ± 41 to 73 ± 31 nm. With refining the average particle size of Gd <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3,</sub> while <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">J</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> in a self-field was monotonously decreased, minimum in-field <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">J</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> values were first increased and then decreased again. With lowering the growth temperature of Gd <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> , the gradual decrease of self-field <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">J</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> may be mainly attributed to the gradual degradation of both in-plane and out-of-plane textures, the variation of the minimum in-field <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">J</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> values might originate mainly from the variation of the stacking fault density, which, however, requires further analysis.

Enhanced photoluminescence properties of Gd (x-1) Sr x O: CdO nanocores and their study of optical, structural, and morphological characteristics

Synthesis of Gd doped Srx O: CdO (x = 1.4, 1.6, 1.8) nanostructures (NS) was achieved through the coprecipitation method by using CTAB (cetyl trimethyl ammonium bromide) with the purpose to investigate the effect of Gd doping on the optical, structural, morphological, and photoluminescence properties at room temperature. Mixed phase of tetragonal crystal structure verified via X-ray diffraction technique, no structural variation was observed except lattice distortion. Size of the crystallites (D), morphology studied by SEM (scanning electron microscopy) analysis, nanoparticles (NPs) crystalized roughly flake-like morphology with homogeneous particle distribution centered at ~ 78 nm, ~56 nm, ~65 nm, ~88 nm for pure and Gd (x-1) doped Sr xO: CdO nanostructure, respectively. Fourier transform infrared spectroscopic investigation (FTIR) revealed the presence of Gd–O–Gd, Cd–O, Sr–O, and OH peaks appeared at ~1321 cm −1, ~1550 cm −1, ~1400 cm −1–3300 cm −1 with small variation in vibration modes due to Gd doping. Optical absorptivity observed in the range of 325 nm–359 nm (redshifted) with absorption edges at 346 nm, 364 nm, and 380 nm for Gd (x-1) doped Sr xO: CdO nanostructure, respectively. This redshift on the bandgap was discussed in terms of new band levels below conduction band. The energy gap was calculated using Kubelka-Munk theory and was found to be in the range of 3.22 eV–2.61 eV. X-ray photoelectron spectroscopy (XPS) performed to determine chemical composition and binding energies of Gd 3d 3/2, Sr 3d 3/2, and Cd 3d 3/2, O1s, and C1s observed at 150.8 eV, 141.6 eV, 411.0 eV, 530.4 eV, and 285.6 eV indicating Gd+3 ion replaces Sr+2 in all concentrations. Our results showed that Gd-doped Sr xO: CdO nanoparticles exhibited enhanced photoluminescence (PL) properties in contrast to the pure Gd2O3 with Gd+3 randomly incorporated into crystal structure, probably in tetrahedral sites. The composition of Gd 0.6 doped Sr x O: CdO NS exhibited photoluminescent emission spectra, peaks centered at 433 ± 3 nm, 449 ± 3 nm, and 469 ± 2 nm (λ excitation = 318 nm) and for Gd 0.8 doped Sr x O: CdO nanostructure showed broad emission peak at 412 ± 2 nm to 433 ± 2 nm (λ excitation = 380 nm), which indicates a reduction in defects with an increase in Gd doping. The transitions can be ascertained with shielding of 4f shells of Gd +3 ions by 6s, 5d shells by the interaction of other Gd +3 ions.

Thermal conductivity of gadolinium added uranium mononitride fuel pellets sintered by spark plasma sintering

Thermal conductivity of spark plasma sintered UN/Gd2O3 and UN/GdN composite pellets with various compositions of Gd2O3 (5.0 to 15.0 wt%) and GdN (3.5 to 38.4 wt%) was measured from 25 °C to 1000 °C using laser flash analyzer (LFA). Overall thermal conductivity of both composite pellets decreases with increasing Gd compositions for the entire temperature range measured. The UN/GdN pellets sintered at high temperature (2000 °C) contained solid-solution (U1-x,Gdx)N phase and exhibited 20–65 % higher thermal conductivity than the UN/Gd2O3 pellets. We also confirmed a two-phase structure in low temperature (1800 °C) sintered UN/GdN pellets, which exhibited 14–25 % higher thermal conductivity than solid-solution UN/GdN pellets. This result may indicate that relatively higher thermal conductivity of UN/GdN composite as burnable absorber fuel could be further enhanced with an optimized microstructure.

Heating events in the nascent solar system recorded by rare earth element isotopic fractionation in refractory inclusions.

Equilibrium condensation of solar gas is often invoked to explain the abundance of refractory elements in planets and meteorites. This is partly motivated, by the observation that the depletions in both the least and most refractory rare earth elements (REEs) in meteoritic group II calcium-aluminum-rich inclusions (CAIs) can be reproduced by thermodynamic models of solar nebula condensation. We measured the isotopic compositions of Ce, Nd, Sm, Eu, Gd, Dy, Er, and Yb in eight CAIs to test this scenario. Contrary to expectation for equilibrium condensation, we find light isotope enrichment for the most refractory REEs and more subdued isotopic variations for the least refractory REEs. This suggests that group II CAIs formed by a two-stage process involving fast evaporation of preexisting materials, followed by near-equilibrium recondensation. The calculated time scales are consistent with heating in events akin to FU Orionis- or EX Lupi-type outbursts of eruptive pre-main-sequence stars.

Highly Energetic and Stable Gadolinium/Bismuth Molybdate with a Fast Reactive Species, Redox Mechanism of Aqueous Electrolyte

The electronic properties and stability of gadolinium-doped bismuth molybdate composites are critical characteristics that determine the efficiency of storing energy reversibly as a propitious electrode for energy storage applications. Gd-doped Bi2MoO6 is presented, which is based on the orthorhombic phase host Bi2MoO6 lattice, where variable amounts of Gd dopant are substituted in the Bi site, resulting in significantly improved energy storage performance. The doping effects with the aim of better understanding the electronic structure of Gd-doped Bi2MoO6 and fine-tuning the properties of energetically favorable material that possesses the most stable crystal structure are reported. The measured X-ray photoelectron spectra of Gd (4d) confirm the presence of the Gd(III) state. The enhanced stability of Gd0.05Bi1.95MoO6 has been attributed to the ability to distribute electron density evenly. In a three-electrode configuration, using aqueous NaOH electrolyte, the Gd0.05Bi1.95MoO6 electrode demonstrated a high specific areal capacitance of 2.15 F cm–2 (the equivalent of 191.5 mAh g–1). The results reported herein are important as they provide an insight into the factors influencing highly energetic and fast reactive species in the Gd(III) composites, which could be a potential anode material for energy storage applications. The optimized anode material is coupled with Ni–Co–Cu ternary oxide cathode and evaluated as a device. The asymmetric supercapattery showed 153 mAh g–1 at a current density of 4 mA cm–2 with an excellent retention of 89% after 1000 long cycles.