Rare Earth Research Articles

Solmers: Versatile hybrid resins for nanometric 3D printing of silica-based photonic components

Owning to their intrinsic properties, silica-based glasses are widely used in various technological fields, especially in photonics. However, high degree of flexibility is yet challenging in realization of next-generation miniaturized optical components. In this work, we develop an approach based on ‶Solmers″ hybrid resins allowing versatile two-photon polymerization 3D printing of silica glasses with 23 nm resolution, doping with Germanium and/or rare-earths elements. Other dopants such as gold nanoparticles were also incorporated for localized metallization. After 3D printing and sintering (1100–1300 °C), high optical quality glasses with low surface roughness (<0.2 nm) were obtained. Structural analyses confirmed the amorphous structure of silica glasses. Various mono- or multi-materials microstructures were successfully fabricated on fused silica substrates. Besides, this approach was extended to the functionalization of optical fibers for optical sensing applications in harsh environment (1000 °C). Compared to organic or organic-inorganic materials, these dense silica-based glasses with enhanced optical and structural properties will open new avenues for the development of emerging advanced optical components.

Geological characteristics of early cretaceous volcanic rocks and analysis of metallogenic potential of uranium mineralization in Moganshan basin, northern Zhejiang province, China

The Moganshan Volcanic Basin is located in the northeastern section of the Ganhang volcanic-tectonic-uranium polymetallic metallogenic belt. To explore the uranium mineralization potential of these volcanic rocks, petrographic, elemental geochemical, zircon U-Pb chronology, and Sr-Nd-Pb isotope analyses were performed on the volcanic rocks in the Moganshan Basin. The results showed that the volcanic rocks within the Moganshan Basin were formed at 130.8 ± 2.0 Ma; In addition, they are Si-rich (SiO2 content of 72.98%–77.32%), alkali-rich (Na2O+ K2O, with ALK values of =7.15–9.74), and potassium-rich (K2O/Na2O content of 1.41–4.34), with light rare earth elements (Rb, Th Nd, Zr, and Hf). Further more, the volcanic rocks within the Moganshan Basin are deficient in Ba, Ta, Nb, and Sr, with a negative europium anomaly (δEu of 0.10–0.17), high ISr (0.71028–0.71160), low εNd(t) values (−6.43–5.77), and other characteristics. The geological characteristics of the volcanic rocks in the Moganshan Basin are the same as those of the volcanic rocks in eastern China, and the formation age is Early Cretaceous. The formation environment is intra-land extensional and tensional. The rock-forming material primarily originates from the upper crust and has a higher average uranium content than that in the Ganhang volcanic belt. Additionally, it is speculated that the Moganshan Volcanic Basin has good potential for uranium mineralization.

Large magnetocaloric effect and giant magnetoresistance in rare earth based intermetallic compound ErAl3: Construction of magnetic phase diagramΔΔΔ.

This study explores the magnetic and magnetotransport behavior of polycrystalline ErAl3 compound. The polycrystalline compound adopts HoAl3-type structures with the R-3m space group, No. 166-2 and hR60 configurations. Multiple magnetic orderings and two field induced metamagnetic transitions are observed. ErAl3 exhibits a significant magnetocaloric effect (MCE), ΔSM = &#xD;15.25 J/kg-K and high relative cooling power (RCP) of 383 J/ kg with applied magnetic field change (ΔH) of 70 kOe near the paramagnetic to ferromagnetic transition, showcasing its potential for magnetic refrigeration technology. The compound also demonstrates metallic behavior, with a notable magnetoresistance of 48.5 % at 2 K due to the suppression of antiferromagnetism. The&#xD;magnetic phase diagram reveals four distinct phases influenced by temperature and magnetic field, identified through the study of the magnetocaloric effect.

Exploring Rare Earth Elements in complex microscopic mineral phases: Inputs from μLIBS imaging

Understanding the distribution and concentration of Rare Earth Elements (REE) within various minerals and ores is crucial in mineralogy and geology for comprehending the micro-scale processes that contribute to the formation of REE-bearing minerals. Laser Induced Breakdown Spectroscopy elemental imaging emerges as a valuable tool due to its spatial resolution (15 μm) and ability for blind and rapid identification of elements within thin rock sections. Geological samples from the metamorphic core of the Zagros orogen (Iran) prepared as thin rock sections have been analyzed by LIBS imaging. Mineralogical phases have been determined from LIBS images of major elements. We first found that the distribution of Yttrium and REEs varies depending on the metamorphic stage. Then, while garnets may exhibit zoning in Mn, we observed that not all of them incorporate Yttrium. Finally, we demonstrated that REEs carriers include bastnaesite (Y Ce La F) and xenotime-like minerals primarily composed of Y with varying amounts of Yb, Gd, and Nd. We also demonstrated that the REEs minerals can exhibit either millimetric size when embedded within andalusite phases, or micrometric size when randomly scattered throughout the matrix. And we have also observed that some samples feature abundant Y-enriched Zircon phases. This study demonstrates that μLIBS imaging enables drawing a comprehensive picture of geological samples down to the micrometric scale. It has become a key technique in this field, providing access to the mineralogy of REE minerals, which is paramount for optimizing the final exploitation process compared to other analytical techniques.

Effect of rare earth element Y content on microstructure, magnetic properties, and electrochemical properties of the as-annealed FeCoNiAl0.2Yx high-entropy alloys

FeCoNi high-entropy alloy (HEA) is widely used in the aerospace and chemical industry. However, the strength and corrosion resistance of the alloy still need to be improved. In this paper, FeCoNiAl0.2Yx (x = 0, 0.05, 0.1, 0.2, and 0.3 in mole ratio) high entropy alloys with different contents of rare earth (RE) element yttrium (Y) were prepared by the vacuum arc melting method, and then the alloys were subjected to annealing treatment at 800 °C/2h. The microstructure, hardness, magnetism, and corrosion performance of FeCoNiAl0.2Yx HEAs in the annealed state with different contents of element Y were analyzed. The results show that the annealed FeCoNiAl0.2Yx HEAs without the addition of element Y and after the addition of element Y both were composed of a face-centered cubic phase. The alloy showed a dendritic structure inside. The element Y was solidly dissolved in the alloys to refine the microstructure of the alloys, and the dendrites were gradually refined with the addition of Y. The Y element caused the phenomenon of lattice distortion inside the alloys, which led to the increase in the alloys’ hardness. The alloy with x = 0.2 showed the greatest exchange of magnetic atoms and the alloy with x = 0.05 showed the lowest coercivity. The alloy with x = 0.1 showed the lowest self-corrosion current density, the broadest passivation zone, the densest dendrites, the smallest grain spacing, and the weakest tendency for intergranular corrosion. The present study shows that the introduction of element Y improves the microstructural morphology, hardness, magnetism, and corrosion properties of FeCoNiAl0.2Yx HEAs in the annealed state.

One-Pot Synthesis of Ce-SSZ-39 Zeolite with Performance in the NH3-SCR Reaction.

Cu-SSZ-39 zeolite with 8-membered rings is regarded as a very promising catalyst in the NH3-SCR reaction, but its hydrothermal stability still remains to be improved. One of the solutions to promote hydrothermal stability is the insertion of rare earth elements in the product. Nevertheless, normal ion exchange of rare earth elements limits their contents in the zeolite product due to their large hydrated ionic radius and alkaline environment under hydrothermal conditions. Herein, we for the first time present a new method for the one-pot synthesis of Ce-SSZ-39 zeolite under solvent-free conditions. The key to success is the use of Ce-FAU zeolite as a precursor. The obtained product shows good crystallinity, sheet-like morphology, large BET surface area, and 4-coordinated Al species. Detailed investigations illustrate that Ce species in the Cu/Ce-SSZ-39 zeolite micropore can prevent the dealumination and thus formation of CuAlOx species during hydrothermal aging at 850 °C for 16 h, giving the excellent hydrothermal stability and thus showing the excellent catalytic performance in the NH3-SCR reaction. One-pot synthesis of Ce-SSZ-39 zeolite with excellent catalytic performance might open a new door for developing very efficient selective catalytic reduction (SCR) catalysts in near future.

Numerical Study on Mechanical Behavior and Electromechanical Properties of Solder-Jointed REBCO-Coated Conductors

As the second-generation high-temperature superconducting conductors, rare earth–barium–copper–oxide (REBCO) coated conductor (CC) tapes have good potential as high-field and high-energy superconductors. In superconducting applications, several joints are required for conjugating comparatively short REBCO CC tapes. Soldering lap joints are the simplest and most commonly applied REBCO CC joints. In addition to joint resistance, the mechanical behavior and electromechanical properties are also crucial for superconducting applications. In this paper, the electromechanical properties and mechanical behaviors of soldering lap joints at 77 K under a self-field were studied. The mechanical behavior was addressed by using a full three-dimensional multilayer elastic–plastic finite element model (FEM) with REBCO CC tape main layers and solder connecting layers. Then, the electromechanical properties were analyzed by using Gao’s strain-Ic degradation general model on the basis of the FEM results. Both the mechanical behavior and electromechanical properties were verified by experimental results. The effects of soldering lap conditions including lap length, soldering thickness and lap style on the electromechanical properties and mechanical behaviors were discussed. The results indicate that shorter overlap lengths and a thinner solder can reduce the premature degradation of Ic due to stress concentrations nearby the joint edges; moreover, the irreversible critical strain is significantly higher in the back-to-back joint approach compared to the widely used face-to-face joint approach.

Easy Access to Ultrahigh-Molecular Weight Poly(1,3-dioxolane) by Rare Earth Triflates

Easy Access to Ultrahigh-Molecular Weight Poly(1,3-dioxolane) by Rare Earth Triflates

High Cerium content Fe‐Ce‐Nd‐B sintered magnets with high coercivity

Ce substitution of Nd in FeNdB sintered magnets is very interesting for reasons of resource efficiency, sustainability and costs. However, the magnetic properties of high Ce‐content magnets are poor. This is mainly due to the lower values of intrinsic magnetic properties of Fe14Ce2B compared to Fe14Nd2B as well as the Laves phase Fe2Ce, which is formed in the grain boundaries and forms flat aggregates for higher Ce‐content. In this paper, sintered magnets with 75 at% degree of substitution of the composition Fe70.9‐[(Ce1‐xLax)0.75Nd0.25]18.8‐B5.8‐M4.5 (M = Co, Ti, Al, Ga, Cu, 0 ≤ × ≤ 0.3) are produced and analyzed. It is shown that a new rare earth rich grain boundary phase is formed adding La and that the Laves phase fraction can be reduced by up to 85%. With increasing La content, the remanence and Curie temperature increase and the temperature coefficient of Hc improves. A coercivity, remanence and maximum energy density of up to µ0Hc = 0.74 T, Jr = 0.98 T and (BH)max = 139.9 kJ/m3 have been achieved.This article is protected by copyright. All rights reserved.

Utilizing rare earth titanates to improve performance of solid-state electrochromic device

Exploring new materials and synthesis recipes are required to enhance the electrochromic performance especially, when used in solid-state devices. Here, polycrystalline gadolinium titanate (Gd2TiO5 or GTO), synthesized using a simple solid-state reaction method, has been used for this purpose by combining it with polythiophene (P3HT). The electrochemical investigation of the Gd2TiO5 doped P3HT electrode has been carried out using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), which reveals the dominance of diffusion-controlled mechanism over charge storage on the electrode surface as compared to the P3HT electrode. The Gd2TiO5 doped P3HT solid-state electrochromic device shows color modulation at 515 nm and 670 nm wavelengths with a color contrast of as high as 79% and 42%, respectively, under an external bias of as low as ±1.4 V. The prepared device switches between maroon to a transparent state in less than a second under the external bias (±1.4 V) with a high coloration efficiency of 346 cm2/C. The device shows improved cycle life over 100 switching cycles at both the wavelengths, which makes it more suitable for real-life applications.

Theoretical Studies on γ-Photon/Neutron Shielding Characteristics of RE3+Co-Doped Borate, Phosphate, and Silicate Glass Systems

The Phy-X program software was used to investigate the γ- and neutron shielding properties of trivalent rare earth co-doped borate-, phosphate- and silicate glasses (G1-G10) concerning elemental composition and density. The attenuation coefficients (μ/ρ and μ), half/tenth value layer (HVL and TVL), and mean free path (MFP) were calculated, and each revealed the influence of rare earth including the Pb, Ba, and Bi elements. Energy and compositional dependent effective atomic number (Zeff), effective electron density (Neff), and effective electron conductivity (Ceff) of all the glasses were studied. On the high-density glasses G6, G9, and G10, the HVL and TVL values are projected to be lower than on the other examined glasses. The neutron radiation shielding abilities of the studied glasses were investigated by determining removal cross-section (RCS). The results were compared to those of commercially available materials such as concrete, graphite, water, and Hematite-serpentine concrete. The γ-ray exposure buildup and energy absorption factor values (EBF/EABF) of glass samples were determined in the energy range of 0.015 to 15 MeV.

Rare Earth Nanoprobes for Targeted Delineation of Triple Negative Breast Cancer and Enhancement of Radioimmunotherapy.

Radiotherapy demonstrates a synergistic effect with immunotherapy by inducing a transformation of "immune cold" tumors into "immune hot" tumors in triple negative breast cancer (TNBC). Nevertheless, the effectiveness of immunotherapy is constrained by low expression of tumor-exposed antigens, inadequate inflammation, and insufficient tumor infiltrating lymphocyte (TILs). To address this predicament, novel lutecium-based rare earth nanoparticles (RENPs) are synthesized with the aim of amplifying radiation effect and tumor immune response. The nanoprobe is characterized by neodymium-based down-conversion fluorescence, demonstrating robust photostability, biocompatibility, and targetability. The conjugation of RENPs with a CXCR4 targeted drug enables precise delineation of breast tumors using a near-infrared imaging system and improves radiation efficacy via lutetium-based radio-sensitizer invivo. Furthermore, the study shows a notable enhancement of immune response through the induction of immunogenic cell death and recruitment of TILs, resulting in the inhibition of tumor progression both invitro and invivo models following the administration of nanoparticles. Hence, the novel multifunctional nanoprobes incorporating various lanthanide elements offer the potential for imaging-guided tumor delineation, radio-sensitization, and immune activation post-radiation, thus presenting an efficient radio-immunotherapeutic approach for TNBC.

Tectonic evolution of the South Pamir Orogen: Insights from the Permian to cretaceous magmatism

The Pamir orogen originated through the amalgamation of various arc terranes. Despite undergoing numerous studies, the subduction polarity and time regarding the accretion processes remain inadequately constrained. To address these issues, we carried out a detailed study of zircon and apatite U-Pb ages, zircon Hf isotopes, and whole-rock geochemistry for the Permian to Cretaceous gabbro, volcanic rocks and granitoids from the Southern Pamir and the Rushan-Pshart suture. Three stages of magmatism are identified, including 279–266 Ma gabbro and andesite to dacite, 209–208 Ma granitoids, and 108–103 Ma gabbro and granitoids, respectively. The Permian gabbro and basaltic andesite to dacite in Pshart Range are enriched in light rare earth elements (LREE) and large ion lithophile elements (LILE), but are depleted in Ta, Nb, and Ti, suggesting formation from an enriched mantle source in a subduction zone. The Late Triassic I-type granitoids are typical arc calc-alkaline magmatic rocks with εHf(t) values varying from −8.7 to −3.5, which mainly sourced from the partial melting of mixed crustal sources predominately consisting mafic rocks with minor metasedimentary rocks. The Early Cretaceous Pshart granites are I-type granites with relatively low εHf(t) values ranging from −14.6 to −2.9, suggesting that they were crust-derived rocks. The Early Cretaceous Bazardara granites are identified as A2-type granites with the εHf(t) values ranging from −18.3 to +5.3, and were derived from mixing of mantle-derived and crust-derived magmas, or interaction between mantle melts and old crustal rocks. The early Cretaceous gabbro exhibits -MORB-like geochemical characteristics with flat REE pattern (La/YbN = 4.96), moderate enrichment of LILEs and weak depletion of Nb, Ta and Ti (Nb/LaPM = 0.94). Thus, the early Cretaceous A2-type granite, E-MORB-like gabbro and volcanic rocks were formed in an extensional setting. Our new data indicate that the southward subduction of the Rushan-Pshart oceanic slab started in the Early Permian and continued to the Late Triassic. Moreover, combining the previous data, we conclude that the Early Cretaceous granites and gabbro in the Southern Pamir formed in an extensional environment due to the southward rollback after northward near-flat subduction of the Neo-Tethyan oceanic lithosphere.

Volume dependence of the charge density wave phase transitions

ABSTRACT We analyse the volume dependence of the charge density wave phase transition temperature T CDW for 16 one and two dimensional materials such as the rare earth tritellurides TbTe 3 , ErTe 3 , TmTe 3 DyTe 3 , the transition metal dichalcogenide 2H-NbSe 2 , and the quasi-one dimensional conductors K 0.3 MoO 3 , NbSe 3 , ( TaSe 4 ) 2 I . The volume dependence is taken in the form of the logarithmic derivative of T CDW in function of the strain components. We point out some characteristics of this parameter. This parameter is dimensionless with an absolute value of about 10 obtained from the measurements of the thermal expansion, the longitudinal elastic constants and pressure dependence for 11 one- and two-dimensional CDW systems. In contrast a huge positive value of about 100 is found at the lower charge density wave transition in TbTe 3 , ErTe 3 , TmTe 3 and DyTe 3 .

Rare Earth Chlorides in Low-Hydration Magnesium Chloride Electrolysis: Mechanistic Insights

Abstract During the molten salt electrolysis of magnesium production, water in the magnesium chloride (MgCl2) feedstock poses significant interference, reducing the current efficiency. Employing rare earth chlorides (RECl3) to assist in dehydrating magnesium chloride and producing Mg-RE master alloys emerges as an effective strategy. This study investigated the transformation process in the hydrolysis reaction of low-hydrate MgCl2 within the molten salt, examining the electrochemical activity of its hydrolysis products using Cyclic voltammetry (CV). Additionally, a thermodynamic analysis of the reaction between hydrolyzate MgO and RECl3 was performed at electrolysis temperatures. By integrating CV and Square wave voltammetry (SWV) with X-ray diffraction (XRD) analysis, the study explored the alterations in the electrochemically active components of the molten salt system following the addition of RECl3 to the KCl-NaCl molten salt containing MgO.

X-Ray fluorescence analysis of paraniobate based ceramics of composition Y&lt;sub&gt;3–x&lt;/sub&gt;Yb&lt;sub&gt;x&lt;/sub&gt;NbO&lt;sub&gt;7&lt;/sub&gt;

A two-stage technique for X-ray fluorescence analysis of ceramic samples of composition Y3–xYbxNbO7 (where x = 0 – 3) has been developed. At the first stage, using the method of fundamental parameters (FPM), a rapid semi-quantitative analysis of ceramic samples and products of intermediate synthesis was carried out to determine their preliminary composition. At the second stage, the quantitative composition of the samples was determined using the constructed calibration dependencies. To construct calibration dependencies a series of reference samples containing 3.16 – 56.55% Y, 8.78 – 71.0% Yb, and 12.83 – 19.70% Nb was synthesized using a method similar to that used for preparation of the ceramic samples under study. Analytical lines of elements free from spectral overlaps and XRF conditions (current and voltage of an X-ray tube, exposure time, method of taking into account the background near the analytical line) were selected. The relative standard deviation of the results of Y, Yb, and Nb determination in ceramic samples did not exceed 0.66%, the relative error was no more than 1.63%. The results obtained were compared with the calculated content of analytes in the samples of stoichiometric composition and with the results of ICP-AES analysis of real ceramic samples. The developed technique provides determination of the main components of ceramic samples and can be used for analytical control of synthesis of rare earth paraniobates.

Desorption of rare earth elements biosorbed on Euglena mutabilis suspensions and biofilms

AbstractIncreasing demand for rare earth elements (REEs) has stimulated research on novel recovery methods from sources like industrial effluents. Our recent study demonstrated that algal biofilms are good candidates for the adsorption of REEs and that the extracellular polymeric substances (EPS) within the biofilm were a key accumulator of REEs. In this work, we measured the desorption kinetics, extents, and selectivity of REEs from the algae Euglena mutabilis in suspensions and biofilms using aqueous solutions of HCl at pH between 1.5 and 4, and Na2EDTA at pH 5. We examined the potential for reusing suspended and biofilm biomass for repeated adsorption–desorption cycles. The desorption kinetics were similar for suspensions and biofilms, with equilibrium being reached within 20 min. The extent of desorption was higher in biofilms with 86% and 95% desorption, compared to suspensions which had 72% and 74% desorption using HCl and Na2EDTA, respectively. We postulate that the difference between suspensions and biofilms is attributed to the binding sites in the EPS matrix of the biofilm being more readily protonated than those at the algal cell wall surface. Heavy REEs were found to preferentially desorb at pH 4 over lighter REEs. After 3 repeated adsorption–desorption cycles, the adsorption capacity of biofilms increased by 280% and 80% using HCl and Na2EDTA, respectively, compared to an 80% decrease in biosorption capacity for the suspension. The increase in biofilm biosorption capacity was attributed to the simultaneous desorption of divalent cations alongside REEs from the EPS increasing the number of available binding sites.

Deciphering the U-Pb dates of sedimentary phosphates: A complex example from the Upper Cretaceous-Lower Paleogene series in northwestern Morocco

Uranium‑lead geochronology rapidly generates dates of rock deposition/formation with reasonable precision and accuracy using laser ablation inductively coupled plasma mass spectrometry, which is needed for bracketing stratigraphy. However, previous radiometric U-Pb dating of biogenic (i.e., bones and teeth) and sedimentary phosphate minerals have had limited success, probably because of the nanometric to micrometric crystallites that generate open system behavior. Sediment lithification inhibiting trace element exchange between minerals and porewaters and thus forcing phosphorus-rich crystallites to adopt a closed system behavior has been suggested for interpreting U-Pb dating of carbonate fluorapatite (CFA). Despite these insights, what remains lacking is extensive U-Pb CFA dating at the regional scale to test whether several processes influence the timing of U-Pb system closure by inhibiting U and Pb exchanges. Here, we report U-Pb CFA dating from four sampling sites in northwestern Morocco to understand better the meaning of U-Pb dates in CFA. The Upper Cretaceous-Lower Paleogene phosphate series yields anomalously low 207Pb/206Pb initial ratios and young dates ranging from 37.3 ± 2.4 Ma to 22.7 ± 0.7 Ma, which does not agree with the terrestrial lead model composition for Paleogene ages and the known biostratigraphic ages, respectively. We argue that ancient radiogenic Pb from leached polymetallic mineralizations of the regional environment have been incorporated into CFA and that a 25 to 40 Ma-long widespread resetting of the U-Pb system has affected the northwestern Moroccan phosphates. Neither CFA-hosted CO32− concentrations nor rare earth element and yttrium contents indicate post-depositional modifications of the chemical nature of phosphate-bearing rocks. Burial diagenesis promoting sediment lithification is one of the mechanisms that have triggered final closure of the U-Pb system of CFA minerals and, interestingly, the sedimentation rate was probably not a controlling factor. Unexpectedly, U-Pb dates of ∼23 Ma from three stratigraphic levels separated by several million years seem to be concomitant with the regional emersion and generalized continentalization of northwestern Morocco, allowing CFA to behave as a closed system. We conclude that the laser ablation inductively coupled mass spectrometry U-Pb dating of biogenic and sedimentary CFA minerals must be carefully employed to date the timing of fossilization or sediment deposition.

ZIF-8 Used for the Selective Recovery of Heavy Rare Earth Elements from Mining Wastewater.

In this study, a sample of 2-methylimidazole zinc salt (ZIF-8) demonstrated high selectivity for the recovery of heavy rare earth elements (REEs) from real rare earth mining wastewater. Results show that the distribution coefficient values of Y3+ (4.02 × 104 mL·g-1), Gd3+ (7.8 × 104 mL·g-1), and Dy3+ (6.8 × 104 mL·g-1) are orders of magnitude higher than those of K+ (359.51 mL·g-1), Mn2+ (266.67 mL·g-1), Ca2+ (396.42 mL·g-1), and Mg2+ (239.48 mL·g-1). Moreover, the desorption efficiency of heavy REEs exceeded 40%. Advanced characterizations and density functional theory (DFT) calculations were utilized to elucidate that the heavy REEs were more likely to bind to the nitrogen atoms of imidazole groups on ZIF-8 compared to non-REEs. Furthermore, the adsorption and desorption of heavy REEs primarily depend on the chemical interaction confirmed by adsorption kinetics, isotherm model, and thermodynamic analysis, which involves the dissociation of water and the formation of REE-O bonds. Finally, the ZIF-8 exhibits a remarkable recovery efficiency of over 40% for heavy REEs in column tests conducted over 7h. The findings reported here provide new insights into the selective recovery of heavy REEs from real mining wastewater.

Modulating the size distribution of preformed BaHfO3 nanocrystals towards effective flux pinning in MOD-derived YBCO-coated conductors

The added BaMO3 (BMO, M = Zr, Hf) nanocrystals into REBa2Cu3O7−δ (REBCO, RE = Y or other rare earth) superconducting films by the technology of preformed nanocrystal addition from colloidal precursor solutions have coarsened after sintering of the REBCO films, which limit the BMO size control and flux pinning enhancement. In the present work, the evolution of the size of BaHfO3 (BHO) nanocrystals in the YBCO films is studied. The collection process of BHO nanocrystals is optimized to successfully separate BHO with an average size of 6 nm into two parts with average sizes of 4.5 nm and 7.7 nm, respectively. The evolution of three different BHO sizes in YBCO superconducting films with a thickness of 2.2 μm and 10 mol% addition reveals that the small-size preformed nanocrystals decomposed at high temperatures to release Hf ions, resulting in the coarsening of other preformed BHO nanocrystals. After modulating the BHO size by reducing the amount of small-size BHO, the coarsening factor is reduced from 1.6 to 1.1, leading to a better in-field performance, especially at low temperatures. At 30 K@1 T, the critical current density (J c) of the 7.7 nm BHO-added YBCO increases by 23% and 50% than cases of 6 nm and 4.5 nm, respectively, being of great guiding value in the technology of performed nanocrystal addition.