Search

Abstract Rare earth metals (REMs), such as Dysprosium (Dy) and Ytterbium (Yb), have experienced unprecedented demand in recent times due to their applications in high-end technologies. REMs are found only in select geographic locations placing tremendous economic constraints on their use. In this work, we have developed Gum Acacia-grafted hydrogels (GmAc-FluoroTerPs) that are capable of selective detection and capture of Dy and Yb. The intrinsically blue fluorescent polymer hydrogel GmAc-FluoroTerP has been optimized for Dy(III) and Yb(III) specific quenching, enabling limit of detection of the REMs at 0.13 nM and 60.8 pM, respectively. A comprehensive structural characterization of the fluorescent hydrogel has been performed via NMR, FTIR, XPS, EPR, TGA, XRD, TEM, SEM, EDX, TCSPC, and DLS. In addition to an in situ generated fluorophore, GmAc-FluoroTerP displays a distinctive aggregation induced emission enhancement in mixed solvents. The complexation of Dy(III)/Yb(III) with GmAc-FluoroTerP hydrogel has been characterized by XPS, TCSPC, and logic gate analyses, and the adsorptive capacity for Dy(III) and Yb(III) are found to be best reported till date as 125.57 mg g−1 and 102.27 mg g−1, respectively. Desorption at acidic pH allows recovery of the REMs. We also report semiconducting behaviour of the native fluorescent hydrogel, that is enhanced upon adsorptive capture of Dy(III) and Yb(III), with calculated band gaps at 1.37, 0.77, and 0.49 eV, respectively. The convergent sensing, capture, and reuse of Dy(III) and Yb(III) presented in this work promises a hitherto unreported template for application on other REMs.

For photocatalysis technology to be applied industrially, there has been a significant increase in the need for visible-light-driven photocatalysts that possess exceptional superparamagnetic characteristics to facilitate easy separation. Hence, in this study, rare earth elements (RE) (Sm, Yb, Dy, Er, and Ho) were systematically doped into manganese ferrite (MF) using the coprecipitation method to serve two purposes, namely, reducing the photogenerated electron-hole recombination during photocatalysis and modifying the magnetic properties of MF to become superparamagnetic. The synthesised Re-doped MF was found to be visible light active, as evidenced by the transient photocurrent response and the obtained band gaps, which were in the range of 1.84–1.93 eV. From the cyclic voltammetry, electrochemical impedance spectroscopy, and Tafel polarization plots, it was evident that different RE element dopants have different effects on improving the electrochemical properties of MF. Overall, fast electron transfer of the synthesised materials was found to decrease in the following order: Sm-MF > Dy-MF > Ho-MF > MF > Er-MF > Yb-MF. The g-factor and peak-to-peak line width were found to be in the range of (2.221–2.317) and (93.17–149.85 mT), respectively. The resonance field and hysteresis loop (H c) were found to be in the range of (289.2–301.86 mT) and (8.24–32.61 mT), respectively. Overall, the synthesised RE-doped MF exhibits ferromagnetic properties, and the obtained small H c values hint at these particles exhibiting superparamagnetic properties. In summary, doping MF with Sm, Dy, and Ho is more desirable as it alters the magnetic properties towards superparamagnetic and improves its electrochemical properties. Thus, this study is of importance in advancing the field of photocatalysis in water treatment and material science. • RE (Sm, Dy, Ho, Er, and Yb) were successfully incorporated into the MF spinel structure. • Sm, Dy and Ho dopants improved the electrochemical and optical properties of MF. • The magnetic properties of MF were improved. • The produced photocatalysts were visible light active. [ABSTRACT FROM AUTHOR]

• Effect of dysprosium on properties of extruded Mg–Zr–Sr–Dy is studied. • Significant improvement in mechanical and corrosion properties is achieved. • Dy addition resulted in dynamic recrystallization and evolution of a RE texture. • Formation of Dy 2 O 3 in Mg(OH) 2 protective films improved the corrosion resistance. In this study, extrusion was performed on Mg‒Zr‒Sr‒Dy alloys for improving their mechanical, corrosion, and biocompatibility properties. Effects of extrusion and alloying elements on the microstructural characteristics, tensile and compressive strengths, corrosion behavior, and biocompatibility were investigated. The Mg‒Zr‒Sr‒Dy alloys were composed of an α-Mg matrix containing { 10 1 ¯ 2 } extension twins and secondary phases of intermetallic compounds Mg 17 Sr 2 and Mg 2 Dy. Evolution of basal and rare earth (RE) textures was observed in the extruded alloys and an increase in Dy content to 2 wt.% resulted in texture randomization and strengthening of the RE component, mainly due to particle-stimulated nucleation and a change from discontinuous dynamic recrystallization to continuous dynamic recrystallization, which also led to an improved tension–compression yield asymmetry of 0.87. Extrusion of the alloys significantly enhanced their tensile and compressive properties due to improved distribution of alloying elements and formation of textures. Corrosion rates tested by hydrogen evolution testing, potentiodynamic polarization, and electrical impedance spectroscopy showed similar trends for each composition, and the lowest corrosion rate of 3.37 mmy−1 was observed for the Mg-1Zr-0.5Sr-1Dy in the potentiodynamic polarization testing. Dy 2 O 3 was observed in the inner layers of the Mg(OH) 2 protective films, whose protective efficacy was confirmed by charge-transfer and film resistances. A comparison among the minimum CRs observed in this study and previously studied as-cast Mg‒Zr‒Sr‒Dy and extruded Mg‒Zr‒Sr alloys, demonstrates that both the extrusion process and addition of Dy in Mg‒Zr‒Sr improved the CR. Similarly, extruded Mg–Zr–Sr–Dy alloys showed improved cell viability and adhesion of human osteoblast–like SaOS2 cells due to increased corrosion resistance and enhanced Sr distribution within the Mg matrix. [ABSTRACT FROM AUTHOR]

Sandwich d/f heterometallic complexes [(Ln(hfac)3)2M(acac)3] (Ln = La, Pr, Sm, Dy and M = Co; Ln = La and M = Ru) were prepared in strictly anhydrous conditions reacting the formally unsaturated fragment [Ln(hfac)3] and [M(acac)3] in a 2-to-1 molar ratio. These heterometallic complexes are highly sensitive to moisture. Spectroscopic observation revealed that on hydrolysis, these compounds yield dinuclear heterometallic compounds [Ln(hfac)3M(acac)3], prepared here for comparison purposes only. Quantum mechanical calculations supported, on the one hand, the hypothesis on the geometrical arrangement obtained from ATR-IR and NMR spectra and, on the other hand, helped to rationalize the spontaneous hydrolysis reaction. [ABSTRACT FROM AUTHOR]

We herein provided a systematical determination of the structural and magnetic properties, especially of the magnetocaloric effect (MCE) and magnetocaloric performances of four rare-earth oxychlorides, i. e., the RE OCl (RE = Ho, Dy, Tb and Gd) compounds. The studied RE OCl compounds are all crystallized in the tetragonal matlockite structure (P 4/ nmm space group) and the RE , O, and Cl elements are with the RE 3+, O2−, and Cl− valence states, respectively. The DyOCl, TbOCl and GdOCl compounds reveal an antiferromagnetic transition at around approximate 9.5, 3.7 and 4.8 K, respectively. The magnetocaloric performances are checked by the maximum magnetic entropy change, relative cooling power, and temperature-averaged entropy change with 5 K lift, which are found to be 14.16 J/kgK, 375.55 J/kg and 13.89 J/kgK for HoOCl, to be 14.88 J/kgK, 488.14 J/kg, and 14.60 J/kgK for DyOCl, to be 14.59 J/kgK, 419.67 J/kg, and 14.42 J/kgK for TbOCl, and to be 16.16 J/kgK, 213.68 J/kg, and 14.39 J/kgK for GdOCl, with the magnetic field change of 0–7 T, respectively. [ABSTRACT FROM AUTHOR]

We herein investigated four rare earth (RE)-based oxides, the RE 2 SiO 5 (RE = Gd, Dy, Ho, and Er) silicates, regarding their structural and cryogenic magnetic properties. All the RE 2 SiO 5 silicates are found to crystallized in a monoclinic structure. X-ray photoemission spectroscopy spectra illustrate that RE , Si and O elements in RE 2 SiO 5 silicates are present as RE 3+, Si4+, and O2−, respectively. The Dy 2 SiO 5 reveals a first-order magnetic transition around 4.5 K. The magnetic phase transition temperatures are probably below 2 K for the RE 2 SiO 5 (RE = Gd, Ho, and Er) silicates. Large cryogenic magnetocaloric effects (MCE) and good magnetocaloric performances were observed in the RE 2 SiO 5 silicates. The MCE parameters in terms of the maximum magnetic entropy changes, the temperature-averaged entropy change (5 K-lift) and refrigerant capacity under a magnetic field change of 0–5 T are determined to be 35.5, 30.4 J/kgK, and 215.7 J/kg for Gd 2 SiO 5 , to be 13.3, 12.9 J/kgK, and 190.5 J/kg for Dy 2 SiO 5 , to be 15.3, 15.1 J/kgK, and 274.1 J/kg for Ho 2 SiO 5 and to be 17.9, 16.5 J/kgK, and 181.14 J/kg for Er 2 SiO 5 , respectively. These derived values of MCE parameters of the RE 2 SiO 5 silicates, especially for Gd 2 SiO 5 , are at similarly high level with or better than those of the updated candidate materials, making them also of potential for practical magnetic refrigeration applications. [ABSTRACT FROM AUTHOR]

Cryogenic refrigeration technology based on magnetocaloric effects plays a critical role in a variety of technological applications. In this paper, we report the cryogenic magnetocaloric effects of a series of sodium-rare earth fluoride samples (Ln = Gd, Tb, Dy, Ho, Er, Tm, Yb) synthesized by the solid-state reaction method. These compounds all crystallize in a hexagonal crystal structure. Down to 2 K, no magnetic ordering was detected, while all compounds show negative Curie–Weiss temperatures indicative of strong antiferromagnetic coupling. Magnetic fields effectively suppress the magnetic fluctuations, leading to a maximum magnetic entropy change of −56 J kg−1 K−1 in NaGdF4 at the magnetic field change from 0 to 50 kOe. These series of compounds are potentially excellent magnetic refrigerants at low temperatures. [ABSTRACT FROM AUTHOR]

High-performance sintered Nd-Pr-Fe-B magnets were successfully prepared by depositing Dy/Tb films on the surface using magnetron sputtering, which resulted in superior grain boundary diffusion (GBD) under heat treatments. The course of the diffusion was assessed using an electron probe microanalyzer (EPMA) and inductively coupled plasma (ICP). The magnetic properties and thermal stability of the magnets before and after diffusion were investigated. The results show that, mainly due to the increased and optimized Nd-Pr-rich phases and the formation of the (Nd,Pr,Dy/Tb)2Fe14B shell structure surrounding the (Nd,Pr)2Fe14B grains, the coercivity of the Dy- and Tb-diffused magnets was enhanced from 16.7 kOe to 24.8 kOe and 28.4 kOe, respectively, while the corresponding maximum energy product (BHmax) was 48.1 MGOe and 48.5 MGOe, respectively. The consumption of Dy/Tb in this work (0.35 wt% Dy in the Dy-diffused magnet and 0.42 wt% Tb in the Tb-diffused magnet) is much lower than that of previously reported magnets with comparable coercivity. Furthermore, Dy- or Tb-diffused magnets exhibit better thermal stability than that of the original magnet, owing to the better resistance to thermal disturbances of the magnets with optimized microstructure. This work can provide useful guidance for preparing Nd-Fe-B magnets with low cost and high performance. [ABSTRACT FROM AUTHOR]

We have systematically studied the crystal structure, cryogenic magnetic properties and MCE in RE 2 MgTiO 6 (RE = Tb, Dy, Ho and Er) DP oxides. The four RE 2 MgTiO 6 samples are all found to crystallize in a monoclinic DP structure (P 2 1 /n space group). The Néel temperature (T N) are found to be 4.7, 4.5, 3.1 and 2.1 K for RE 2 MgTiO 6 (RE = Tb, Dy, Ho and Er) DP oxides, respectively. Moreover, the maximum magnetic entropy change (-Δ S M max) together with relative cooling power (RCP) near T N under a magnetic field change (ΔH) of 0–7 T are evaluted to be 16.85, 360.59 for Tb 2 MgTiO 6 , 17.72, 381.05 for Dy 2 MgTiO 6 , 15.92, 398.14 for Ho 2 MgTiO 6 and 22.95 J/kg K, 459.09 J/kg for Er 2 MgTiO 6 , respectively. The excellent cryogenic MCE suggest that RE 2 MgTiO 6 (RE = Tb, Dy, Ho and Er) DP oxides can be used as a promising candidate material for cryogenic magnetic refrigeration. [ABSTRACT FROM AUTHOR]

The effect of ionic radii sizes on magnetostriction is studied in relation to structural and magnetic properties. To explore the effect of the chemical pressure, nanoparticles of rare‐earth (RE) orthoferrites, SmFeO3, DyFeO3, HoFeO3, and LuFeO3 are studied using X‐ray diffraction, field emission scanning electron microscopy, and Raman spectroscopy. Magnetic and magnetostriction measurements are also performed. In these orthoferrites, the coordination of the RE ion is eightfold, whereas the RE ionic radii are significantly different, which directly influences the structural parameters. The distortion of FeO6 octahedra is observed as a result of changing chemical pressure within the lattice. The different magnitudes of magnetostriction in RE orthoferrites can be attributed to the different degrees of distortion of FeO6 octahedra, R–O dynamics, and spin–orbit interactions in the system. The maximum value of magnetostriction (∼ 19 ppm) and magnetization at 2 K (30.64 emu/g) is demonstrated by HoFeO3. Comparison of structural parameters of the samples to their respective bulk counterparts indicated relative structural distortion in nanoparticles. [ABSTRACT FROM AUTHOR]

To investigate novel glass materials applicable to W-LED, we designed and prepared a series of glasses with varying compositions. The compositions of the glasses were (64-x)B 2 O 3 –15Al 2 O 3 –10Na 2 O–10Bi 2 O 3 -xCaF 2 -0.5Dy 2 O 3 -0.5Eu 2 O 3 (x = 0, 5, 10, 15, 20, 25). The glasses were synthesized using the melting quenching method. The effect of CaF 2 on the structural feature of fluoroborate glass was studied by infrared spectroscopy analyses. Determination of fluorine content in glass by 19F NMR inversion spectroscopy. The absorbance of glass increased as the CaF 2 content increased in the visible and ultraviolet light ranges. The optical band gap of the prepared glasses was obtained from the absorption spectrum, which confirmed the existence of nonbridging oxygen (NBO) in the glass network structure. The fluorescence lifetime of the glass increases with increasing CaF 2 content, and the quantum yield of the glass first increases and then decreases. In addition, fluoroborate glass had a lower Urbach energy, indicating that its network structure was relatively uniform and stable. In contrast, the increase in Urbach energy is due to the substitution of CaF 2 , leading to more defects. By adjusting the excitation wavelength and CaF 2 content, the color temperature (1598–3346 K) and color rendering index (36–63) of fluoroborate glass can be effectively adjusted. These results show that the prepared Dy/Eu co-doped fluoroborate glasses have a potential application in white lighting. [ABSTRACT FROM AUTHOR]

The reaction of UO2 with the respective lanthanide metal and purified graphite in an arc-melting furnace led to the formation of solid solutions of the composition LnxU1−xC2, with Ln = Tb, Dy, Ho, Tm, and Lu. They all crystallize in the tetragonal CaC2 type structure (I4/mmm, Z = 2). Elemental analyses of selected samples (EDX) confirm that the composition of the resulting solid solution is in reasonable agreement with the nominal (weighed-in) composition of the starting materials, i.e., a significant evaporation of the lanthanide metals during the arc-melting synthesis does not occur. The lattice parameters of the solid solutions were extracted using Le Bail fits of high-resolution synchrotron powder diffraction data (beamline P02.1, DESY, Hamburg, Germany; beamline BL 09, DELTA, Dortmund, Germany), revealing ideal Vegard behavior for all five solid solutions. XANES investigations on all compounds at the Ln-LIII and U-LIII edges reveal that the occupancies of the U-6d orbitals decrease with increasing x, whereas the occupancies of the Ln-5d orbitals increase, pointing to an electron transfer from the uranium to the lanthanide cations. Examination of the shifts of the absorption edge (E0) leads to the same finding. [ABSTRACT FROM AUTHOR]

A series of spectrally tunable Dy3+/Eu3+-coactivated double perovskites SrLaLiTeO 6 (SLLT) were synthesized via solid-state ceramic route under air condition. Considering differences of ionic radius and valences among the dopants and host cations, Dy3+/Eu3+ are all inclined to enter La site, though slight occupations in Sr site cannot be completely ruled out. Dy shows narrow band emissions in blue (B) to yellow (Y) region, which is stemmed from magnetic (4F 9/2 → 6H 15/2) and electric (4F 9/2 → 6H 13/2) dipole transitions, respectively. Eu3+ exhibits orange-red (O–R) emissions, with two dominant peaks located at ∼ 593 and 617 nm from magnetic (5D 0 → 7F 1) and electric (5D 0 → 7F 2) dipole transitions, which could be used as compensation for the red-emitting portion in pc- w LEDs via energy transfer (ET) from Dy to Eu to overcome the disadvantage of low excitation efficiency. The substitutional local site symmetry could be regularly modified along with severely impacting on Y/B and R/O ratios for Dy and Eu emission colors via simply modifying the doping contents, due to changes in bond lengths and Coulomb potentials from interconnected octahedrons [LiO 6 ] and [TeO 6 ] around the dopants. The fabricated pc- w LED via combining a commercial n -UV LED chip with the SLLT: Dy/Eu, exhibited splendid EL performance, with the CIE coordinate is calculated to be (0.3690, 0.3539), CCT of 3232 K, and CRI (R a) of 86.5. Altogether, it manifests that the stable SLLT: Eu and SLLT: Dy/Eu are potentially good candidates for applications as red and white phosphors, respectively in indoor plant growth LED and pc- w LEDs. • Dy/Eu is more inclined to enter La site determined via Rietveld, Raman and FTIR tests. • ET mechanism belonged to the d-d interaction is detailed studied via spectral analysis. • Local site symmetry is successfully modulated via simply changing in concentration of dopants. • PL from SLLT: Dy/Eu cold be well tunned via both the ET and local site symmetry. • Warm white light via the ' n -UV LED + codoped white emitting phosphor' is achieved. [ABSTRACT FROM AUTHOR]

Rare earth element (REE) permanent magnets (NdFeB) are a critical element in a vast and growing number of industrial applications. In consumer electronics, a broad category encompassing computer, CD, and DVD hard drives, in addition to the ubiquitous cell phones, the nominal NdFeB magnet content may be small, but the global market share for this sector accounts for almost 30% of NdFeB demand, due to a large and continually increasing consumer base. It is estimated that wind turbines that primarily employ permanent magnets will add roughly 110 GW annually of on- and off-shore capability over the next few years. Electric vehicles (EVs) and E-bicycles (EBs) equipped with permanent magnet motors comprise the transportation contribution. Permanent magnet motors have garnered nearly 100% of the market share among EV manufacturers worldwide. Industrial, professional service, and personal robots, most using permanent magnets, are also included in the projected global need for rare earths, particularly Nd and Dy. The sector projects significant growth of approximately 10% across robotic categories. In this paper, we calculate the future demand for Nd and Dy through 2050 across these sectors using a compounded annual growth rate coupled with magnet weight and rare earth content. Uncertainties in the estimates, such as the true global production of Nd, a range of end-product scales and/or unit types in each sector, varied magnet compositions, and the variety of uses within a sector, are all considered. [ABSTRACT FROM AUTHOR]

Thermodynamic databases are essential to understanding alloy properties and guiding materials design. In this work, the mixing enthalpies of the liquid phase in the Gd-Te, Dy-Te and Ho-Te binary systems are calculated using Ab-initio Molecular Dynamics (AIMD) simulations and the thermodynamic parameters are determined using the CALculation of PHAse Diagrams (CALPHAD) method combined with the phase equilibrium data and thermodynamic data. The associated solution model is employed to describe the liquid phase of these systems. The sublattice model (Gd,Te)0.0296(Gd)0.4(Te)0.5714, (Dy,Te)0.0286(Dy)0.4286(Te)0.5714 and (Ho,Te)0.5(Te)0.5 are utilized to describe Gd2Te3, Dy2Te3 and HoTe, respectively. The line compounds, i.e. GdTe, DyTe, and DyTe2, are modeled using the stoichiometric model. The calculated results can describe the experimental and thermodynamic information reported in the literature. In addition, the existence of a liquid-liquid separation in the Dy-rich side in the Dy-Te binary system is proposed in this work. [ABSTRACT FROM AUTHOR]

Kaolinite is one of the principal rare earth element (REE) ion-adsorption clays that hosts a wide range of elements, including Dy(III) as a representative example. Ammonium sulfate is a typical salt used to leach REEs. Due to the carbon dioxide emissions which occur during ammonia production, it is urgently necessary to develop low environmental pollution leaching agents that can replace (NH4)2SO4. MgSO4 is regarded as the most promising eco-friendly leaching agent. Herein, the first-principles plane-wave pseudopotential method based on the density functional theory (DFT) was used to investigate the stable adsorption structures of Dy(III) and its hydrated ions, MgSO4 leaching agent ions and the corresponding hydrated ions on the surface of kaolinite, which revealed the adsorption mechanism of Dy(III), Mg(II), and SO42− on the silico–oxygen plane and the aluminum–hydroxyl plane of kaolinite. Based on the research results of the steric hindrance effect of Dy(III) on the silico–oxygen plane and the aluminum–hydroxyl plane of kaolinite, the adsorption of Dy(H2O)103+ was more stable on the silico–oxygen plane. It was easier to leach out Dy(III) with MgSO4, while SO42− tended to interact with the rare earth ions in an aqueous solution. The results provide theoretical guidance for efficient rare earth extraction and obtaining novel efficient leaching agents. [ABSTRACT FROM AUTHOR]

Atomic data are fundamental for plasma diagnostics in laboratory and astrophysics through spectroscopy. These data are extensively present in data bases for light elements, however incomplete for high-mass atoms. This paper presents the results of systematic spectroscopy of 17 elements with high Z , expected to be produced in kilonova events generated by neutron star mergers, whose spectral lines are not yet fully identified in stellar spectra and fusion devices. Experimental data are from échelle high-resolution (λ/Δλ = 60 000) spectroscopy of hollow cathode lamps obtained with the Catania Astrophysical Observatory Spectropolarimeter covering the 3700–10 000 Å range in a single exposure. A total of about 7700 spectral lines with energy level classification not previously listed in the NIST, Kurucz, and VALD data bases are here reported for neutral and singly ionized atomic transitions. For the spectral lines of any species, we report the measured wavelengths and their relative intensities. If possible, we also estimate the transition probabilities under the assumptions of optically thin emission and electric-dipole transitions. These are converted into oscillator strengths ready to be inserted in astrophysical data bases for spectral synthesis. [ABSTRACT FROM AUTHOR]

The hot spot extraction agent N,N,N′,N′-tetraoctyl-3-oxoglutaramide (TODGA) has the advantages of novelty, high efficiency and environmental protection in the separation of rare earths by tandem extraction. In this paper, the characteristic parameters for the separation of dysprosium, erbium, thulium and ytterbium ions in the TOGDA–kerosene/hydrochloric acid system for tandem extraction were calculated. Using a 10% TODGA–kerosene/5 mol·L−1 hydrochloric acid extraction system, the mixture containing Dy3+ 0.258 mol·L−1, Er3+ 0.252 mol·L−1, Tm3+ 0.248 mol·L−1 and Yb3+ 0.242 mol·L−1 can be separated by three separation steps, and four products of Dy3+, Er3+, Tm3+ and Yb3+ can be obtained. The purity of the four products was 99.80%, 99.20%, 99.70% and 99.70%, and the yields were 99.03%, 98.97%, 97.88% and 96.98%, in order. In this paper, the reasons were analyzed for the differences in the ability of the TODGA system to extract heavy rare earth ions (REEs) in terms of density functionality, complex structure and bond valence model. These will provide more basic data and guidance for the industrial application of TODGA. [ABSTRACT FROM AUTHOR]

In this study, we investigated the structures of lanthanide (Eu(III), Dy(III), and Gd(III)) complexes with p-coumaric (p-CAH2) and caffeic (CFAH3) acids using the FTIRKBr, FTIRATR, and Raman spectroscopic methods. The compositions of the solid phase caffeinates and p-coumarates were obtained on the basis of the amounts of hydrogen and carbon determined using an elemental analysis. The degree of hydration and the thermal decomposition of each compound were examined via a thermal analysis of TG, DTG, and DSC. Antioxidant spectroscopic tests were performed using the DPPH (1,1-diphenyl-2-picrylhydrazyl radical), FRAP (ferric reducing antioxidant activity), and ABTS (2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) (diammonium salt radical cation) methods. The antimicrobial activity of each compound against Escherichia coli, Bacillus subtilis, and Candida albicans was investigated. The electrical properties of the liposomes which mimicked the microbial surfaces formed in the electrolyte containing the tested compounds were also investigated. The above biological properties of the obtained complexes were compared with the activities of p-CAH2 and CFAH3. The obtained data suggest that lanthanide complexes are much more thermally stable and have higher antimicrobial and antioxidant properties than the ligands (with the exception of CFAH3 in the case of antioxidant activity tests). The Gd(III) complexes revealed the highest biological activity among the studied lanthanide complexes. [ABSTRACT FROM AUTHOR]

Copyright of Revista de la Academia Colombiana de Ciencias Exactas, Físicas y Naturales is the property of Academia Colombiana de Ciencias Exactas, Fisicas y Naturales and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Sm3+ doped and RE3+ (RE = Dy, Er, Gd, La, Nd, Tb)-co-doped CaB6O10 phosphors were prepared at 800°C by the solid-state reaction method. The obtained powders were structurally characterized by X-ray diffraction and Fourier transform infrared analyses. The influences of co-doping rare earth ions on their luminescent properties were also investigated. The emission spectra of the CaB6O10:Sm3+ phosphors consisted of some sharp emission peaks of Sm3+ ions centered at 561, 601, 649, and 708 nm, generating bright orange–red light. The concentration quenching occurred when x equals 0.05 for CaB6O10:xSm3+ phosphor. No remarkable differences were found from excitation spectra of co-doped phosphors CaB6O10:Sm3+, RE3+ in contrast with that of phosphor CaB6O10:Sm3+. The introduction of charge compensator RE3+ (RE = Dy, Er, Gd, La, Nd, Tb) into the host reduced the luminescence intensity of the CaB6O10:Sm3+ phosphors. [ABSTRACT FROM AUTHOR]

A series of 16 mol% CeO 2 -2 mol% Re 2 O 3 co-stabilised zirconia (ZrO 2) (16Ce4ReSZ, Re Eu, Gd, Dy, Y, Er, Yb) ceramic materials were synthesised using a chemical coprecipitation– high-temperature roasting method. Their phase structure, high-temperature phase stability, mechanical properties, thermal conductivity and coefficient of thermal expansion (CTE) were investigated. The results show that the ZrO 2 tetragonal phase co-stabilised by CeO 2 and Re3+ with a smaller radius has better stability. The 16Ce4ReSZ (Re Dy, Y, Er, Yb) materials have high fracture toughnesses, low thermal conductivities, and high CTE values. As the radius of the Re3+ ions decreases, the lattice energy increased, while the lattice distortion decreases, the CTE decreases slightly and the thermal conductivity of the material increases slightly. Owing to the high phase stability of 16Ce4YbSZ, its mechanical properties are best after 100 h of sintering at 1400 °C. [ABSTRACT FROM AUTHOR]

The superconducting transition temperatures (T c ) of RbGd 2 Fe 4 As 4 O 2 , RbTb 2 Fe 4 As 4 O 2 , and RbDy 2 Fe 4 As 4 O 2 are 35 K, 34.7 K, and 34.3 K without doping, respectively. For the first time, we have studied the high-temperature nonmagnetic state and the low-temperature magnetic ground state of 12442 materials, RbTb 2 Fe 4 As 4 O 2 and RbDy 2 Fe 4 As 4 O 2 , using first principles calculations and comparing them with RbGd 2 Fe 4 As 4 O 2 . We also performed a detailed study of the effects of lanthanides and bilayer Fe 2 As 2 . We predict that the ground state of RbLn 2 Fe 4 As 4 O 2 (Ln = Gd, Tb, and Dy) is spin-density-wave-type, in-plane, striped antiferromagnets, and the magnetic moment around each Fe atom is about 2 μ B . We also found that the structural differences caused by the simple ionic radius have little effect on the properties of these three materials. Different lanthanide elements themselves play a major role in the electronic properties of the materials. It can be confirmed that the effect of Gd on RbLn 2 Fe 4 As 4 O 2 is indeed different from that of Tb and Dy, and the presence of Gd is more conducive to interlayer electron transfer. This means that Gd can transfer more electrons from the GdO layer to the FeAs layer compared to Tb and Dy. Therefore, RbGd 2 Fe 4 As 4 O 2 has a stronger internal coupling strength of the bilayer Fe 2 As 2 layer. This can explain why the T c of RbGd 2 Fe 4 As 4 O 2 is slightly higher than that of RbTb 2 Fe 4 As 4 O 2 and RbDy 2 Fe 4 As 4 O 2 . [ABSTRACT FROM AUTHOR]

Using the heavy rare earth Dy element to improve coercivity is the most common solution for hindering the reduction in magnetic properties in the Nd–Fe–B magnet, and the effective utilization of Dy has become the focus of research in industrial society. In this work, we investigated the influence of DyHx addition and diffusion methods on the microstructure, magnetic performance, and thermal stability of the Nd–Y–Fe–B magnet with a Y-rich core structure. The coercivity of the DyHx addition magnet increases from 9.45 kOe to 15.51 kOe when adding 1.6 wt.% DyHx, while the DyHx diffusion magnet increases to 15.15 kOe. According to the analysis of the microstructure and elemental distribution, both Dy-rich shells were basically formed due to the diffusion process of Dy atoms. The Dy-rich shell in the DyHx addition magnet was similar with the original core–shell structure in the Nd–Y–Fe–B magnet. However, the distinct dual-shell structure consisting of a thinner Dy-rich shell and a Y-lean shell was constructed in the DyHx diffused magnet, contributing to the superior coercivity increment and Dy utilization efficiency. Furthermore, the remanence of the DyHx diffused magnet is up to 12.90 kG, which is better than that of the DyHx addition magnet (12.59 kG), due to fewer Dy atoms entering the 2:14:1 matrix grain to cause the antiferromagnetic coupling with Fe atoms. Additionally, the thermal stability of the DyHx diffusion magnet is also better than that of the DyHx addition magnet, owing to the elevated coercivity at room temperature, which expands the application range of the Nd–Y–Fe–B magnet to a certain extent. [ABSTRACT FROM AUTHOR]

In the R–Ru–In (R—rare earth element) systems in the area with a high content of rare-earth elements (>60 at %), a number of isostructural compounds R26(RuxIn1 – x)17 (R = Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Lu) were found, which crystallize in a tetragonal cell (P4/mbm) with the Sm26(Co0.65Ga0.35)17 structure type, as well as Pr21Ru8.2In5 compounds in a tetragonal cell (I4/mcm) with the Y3Rh2 structure type and Gd6Ru2In in a rhombic cell (Immm) with the Ho6Co2Ga structure type. The samples were prepared by arc-melting the stoichiometric quantities of elementary components. The structures were determined by single-crystal X-ray diffraction and refined by the Rietveld method using powder patterns. Compounds R26(RuxIn1–x)17 (R = Dy, Ho, Er, Tm, Lu) exist in the homogeneity range 0.28 < x < 0.47. All crystal structures of the obtaining compounds are based on a frame from atoms of rare earth elements, inside which are smaller in size atoms of ruthenium and indium. A general fragment of all the considered structures are columns of various lengths from InR8 tetragonal prisms and RuR8 tetragonal antiprisms conjugated by mutual bases. The new compounds have a congruent melting pattern. [ABSTRACT FROM AUTHOR]

The atom oxidation states were determined using the binding energies of the core S2p-, Cu2p-, Cr2p-, and Ln3d-levels in CuCr0.99Ln0.01S2 (Ln = Dy–Lu) solid solutions. The charge distribution on the matrix elements (Cu, Cr, and S) remained unaffected after cationic substitution. The sulfur atoms were found to be in the S2− oxidation state, the copper–Cu+, and the chromium–Cr3+. The cationic substitution of the initial CuCrS2-matrix occurred via the isovalent mechanism. The obtained results were compared with the electrophysical properties for CuCr0.99Ln0.01S2. The measured carrier concentration was from 1017 to 1018 cm−3. The largest Seebeck coefficient value of 157 µV/K was measured for CuCr0.99Yb0.01S2 at 500 K. The cationic substitution with lanthanides allowed one to enhance the Seebeck coefficient of the initial CuCrS2-matrix. [ABSTRACT FROM AUTHOR]

Zinc (Zn) and its alloys are receiving great attention as promising biodegradable materials due to their suitable corrosion resistance, good biocompatibility, and highly desirable biofunctionality. Nevertheless, the low mechanical strength of pure Zn impedes its practical clinical application and there have been calls for further research into the Zn alloys and thermomechanical processes to enhance their mechanical properties and biocompatibility. Here, we report on the alloying efficacy of rare earth elements (REEs) including erbium (Er), dysprosium (Dy), and holmium (Ho) on the microstructure, mechanical properties, corrosion and wear behavior, and in vitro biological properties of Zn–1Mg–0.1RE alloys. Microstructural characterization revealed that the addition of 0.1 wt.% REEs had a significant refining effect on the grain size of the α–Zn matrix and the second phases of the alloys. Alloying of the REEs and hot-rolling effectively improved the mechanical properties due to both precipitation strengthening of the second phases of ErZn 5 , DyZn 5 , and Ho 2 Zn 17 and grain-refinement strengthening. The highest ultimate tensile strength of 259.4 MPa and yield strength of 234.8 MPa with elongation of 16.8% were achieved in the hot-rolled Zn–1Mg–0.1Ho. Alloying of REEs also improved the wear and corrosion resistance, and slowed down the degradation rate in Hanks' solution. Zn–1Mg–0.1Er showed the highest cytocompatibility of MC3T3-E1 cells cultured directly on the alloy surface and of MG-63 cells cultured in the alloy extract. Zn–1Mg–0.1Dy showed the best anticoagulant property among all the alloys. Overall, these Zn–1Mg–0.1RE (Er, Dy, and Ho) alloys can be considered promising biodegradable metallic materials for orthopedic applications. Image, graphical abstract [ABSTRACT FROM AUTHOR]

Recently, since the demand of rare earth permanent magnet for high temperature applications such as an electric motor has increased, dysprosium (Dy), a heavy rare earth element, is becoming important due to severe bias in its production. To fulfill the increasing need of Dy, recycling offers as a promising alternative. In recycling of rare earths, Hydro-metallurgical extraction method is mainly used however it has adverse environmental effects. Liquid metal extraction on the other hand, is an eco-friendly and simple method as far as the reduction of rare earth metal oxide is concerned. Therefore, liquid metal extraction was studied in this research as an alternative to the hydro-metallurgical recycling method. Magnesium (Mg) is selected as solvent metal because it doesn't form intermetallic compounds with Fe, B and has a low melting and low boiling point. Extraction behavior of Dy in (Nd,Dy)-Fe-B magnet is observed and effect of Mg ratio on extraction of Dy is confirmed. [ABSTRACT FROM AUTHOR]

The electronic and band structures of ternary RNiSb and binary RSb compounds for R = Tb, Dy, Ho, have been investigated using an ab initio method accounting for strong electron correlations in the 4f shell of the rare-earth metals. These ternary compounds are found to be semiconductors with the indirect gap of 0.21, 0.21, and 0.26 eV for Tb, Dy, and Ho(NiSb), respectively. In contrast, in all binary RSb compounds, bands near the Fermi energy at the Г and X points are shifted relatively to RNiSb and form hole and electron pockets, so the energy gap is closed in RSb. The band structure typical for semimetals is formed in all RSb compounds for R = Tb, Dy, Ho. For the first time, we identify similar features near the Fermi level in the considered binary semimetals, namely, the presence of the hole and electron pockets in the vicinity of the Г and X points, the nonsymmetric electron pocket along Γ–X–W direction and hole pockets along the L–Γ–X direction, which were previously found experimentally in the other compound of this series GdSb. The magnetic moment of all considered compounds is fully determined by magnetic moments of the rare earth elements, the calculated effective magnetic moments of these ions have values close to the experimental values for all ternary compounds. [ABSTRACT FROM AUTHOR]

Bulk metallic glasses (BMGs) are a type of metal materials with long-range disordered atomic structure, which possess numerous unique physical and chemical properties and broad development prospects compared to traditional alloys. However, the insufficient glass-forming ability (GFA) and brittle fracture of BMGs have become the key issues of sever limitation of their application. Herein, we have successfully achieved the bi-directional enhancement of both GFA and mechanical properties by co-doping Ti and Dy with (Zr 56 Cu 2 4 Ni 10 Al 10) 100-y-x Dy x Ti y BMGs. We find that the effects of co-doping Ti and Dy has exceeded that of single-element doping in Zr-based BMGs. Compared to BA, Co-doping by 2.0 at.% of Ti and 0.5 at.% of Dy can significantly increase the fracture strength from 1410 MPa to 2000 MPa, and effectively promoted the excellent GFA up to 10 mm in (BA) 100-y-x Dy x Ti y BMGs. Our results demonstrate that the co-doping by Dy and Ti in Zr-based BMGs provides a novel and effective method to solve classical mysteries of mechanical properties and the GFA in BMGs. • Co-doping of rare earth elements and alloying elements to improve the overall performance of amorphous alloys is proposed. • The resultant (Zr 56 Cu 24 Ni 10 Al 10) 97.5 Dy 0.5 Ti 2.0 amorphous alloy exhibits high intensity up to 2000 MPa , GFA to 10 mm, as well as good plasticity. • The method is simple to operate and can be directly applied in industry to improve the GFA and mechanical properties of amorphous alloys. [ABSTRACT FROM AUTHOR]

There is an immense research interest in molecular hybrid materials posing novel magnetic properties for usage in spintronic devices and quantum technological applications. Although grafting magnetic molecules onto carbon nanotubes (CNTs) is nontrivial, there is a need to explore their single molecule magnetic (SMM) properties post-grafting to a greater degree. Here, we report a one-step chemical approach for lanthanide-EDTA (Ln = GdIII, 1; TbIII, 2 and DyIII, 3) chelate synthesis and their effective grafting onto MWCNT surfaces with high magnetic bistability retention. The magnetic anisotropy of an Ln-CNT hybrid molecular system by replacing the central ions in the hybrid complex was studied and it was found that system 1 exhibited a magnetization reversal from positive to negative values at 70 K with quasi-anti-ferromagnetic ordering, 2 showed diamagnetism to quasi-ferromagnetism and 3 displayed anti-ferromagnetic ordering as the temperature was lowered at an applied field of 200 Oe. A further analysis of magnetization (M) vs. field (H) revealed 1 displaying superparamagnetic behavior, and 2 and 3 displaying smooth hysteresis loops with zero-field slow magnetic relaxation. The present work highlights the importance of the selection of lanthanide ions in designing SMM-CNT hybrid molecular systems with multi-functionalities for building spin valves, molecular transistors, switches, etc. [ABSTRACT FROM AUTHOR]

The nanostructured lanthanide-silica materials of the Ln–SiO2 type (Ln = La, Ce, Pr, Nd, Eu, Gd, Dy, Yb, Lu) were synthesized by the hydrothermal method at 100 °C, using cetyltrimethylammonium as a structural template, silica gel and sodium silicate as a source of silicon, and lanthanide oxides, with Si/Ln molar ratio = 50. The resulting materials were calcined at 500 °C using nitrogen and air, and characterized by X-ray diffraction (XRD), Fourier-Transform infrared absorption spectroscopy, scanning electron microscopy, thermogravimetry (TG), surface area by the BET method and acidity measurements by n-butylamine adsorption. The XRD and chemical analysis indicated that the SiO2 presented a hexagonal structure and the incorporation of lanthanides in the structure changes the properties of the Ln–SiO2 materials. The heavier the lanthanide element, the higher the Si/Ln ratio. The TG curves showed that the decomposition of the structural template occurs in the materials at temperatures below 500 °C. The samples showed variations in specific surface area, mean pore diameter and silica wall thickness, depending on the nature of the lanthanide. The incorporation of different lanthanides in the silica generated acid sites of varied strength. The hydrothermal stability of the Ln–SiO2 materials evaluated at high temperatures, evidenced that the properties can be controlled for application in adsorption and catalysis processes. [ABSTRACT FROM AUTHOR]

Standard enthalpies of formation at 298.15 K, Δ f H 298. 15 ∘ , for RCoO 3-δ (R = La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Y) perovskite-type rare-earth cobaltites were obtained from the combined results of drop and reduction calorimetry. The relationship between the oxygen nonstoichiometry, δ, and thermodynamics of RCoO 3-δ was discussed. The fact that RCoO 3-δ with smaller ionic radius of R3+ tend to be less stable, having more positive enthalpy of formation from binary oxides (CoO and R 2 O 3), Δ f , o x H 298. 15 ∘ , was confirmed for all the studied RCoO 3-δ. Drop calorimetry results were also used in discussing, comparing and assessing the literature heat capacity, C p T , data for RCoO 3-δ (R ≠ Y). For YCoO 3-δ , both Δ f H 298. 15 ∘ and C p T were obtained for the first time solely from the drop calorimetric results; Δ f H 298. 15 ∘ values determined by two different methods perfectly agree with each other. The reference data and C p T of RCoO 3-δ were used to calculate Δ f H 298. 15 ∘ from the published EMF measurement results so as to compare the available Δ f , o x H 298. 15 ∘ (RCoO 3-δ) values. An unusual dependence of Δ f H 298. 15 ∘ (LaCoO 3-δ) on its heat treatment history was identified and supported by the additional isoperibolic solution calorimetry measurements. • Enthalpies of formation of several rare-earth cobaltite perovskites were measured. • The primary methods were reduction reaction calorimetry and drop calorimetry. • The implications of non-zero oxygen nonstoichiometry were discussed. • Heat capacity and formation enthalpy of YCoO 3 were measured for the first time. • Enthalpic stability of RCoO 3 is lower when R3+ is smaller (R = rare-earth metal). [ABSTRACT FROM AUTHOR]

[Display omitted] • Developed TOPO-based hydrophobic eutectic solvents for critical metal recovery. • HDES effectively recovered Nd(III) and Dy(III) from 1 M HNO 3. • THY:TOPO(1:1) showed highest separation factors for Nd/Fe and Dy/Fe. • THY:TOPO(1:1) selectively extracted Nd, Dy, and Pr from NdFeB samples. • TOPO-based HDES offer eco-friendly approach for metal recovery. Integral to emerging technologies, the escalating demand for NdFeB magnets has emphasized their pivotal role. Yet, natural resource depletion intensifies the supply challenge. Nd (III) and Dy (III), classified as critical metals, compound this concern. Recycling these metals from secondary sources, particularly discarded NdFeB magnets, presents a compelling and sustainable strategy. Here, we employ hydrophobic eutectic solvents (HDES) prepared by mixing an extractant trioctylphosphine oxide (TOPO) with hydrogen bond donors thymol (THY), menthol (MEN), or lauric acid (LAAC) in 1:1 ratio. The prepared HDES was used as an extractant and hydrophobic phase to recover Nd(III) and Dy(III) from magnet leachate, thus avoiding the usage of volatile organic solvents. All three HDES formulations effectively extracted Nd(III) and Dy(III) from 1 M HNO 3. Notably, the THY:TOPO (1:1) composition showcased the most remarkable performance in terms of both separation factor and extraction capacity. Stripping Nd(III) and Dy(III) from loaded HDES was achieved using 2 mol/L H 2 SO 4. Through the construction of a McCabe-Thiele diagram and the execution of counter-current experiments, the complete recovery of both Nd(III) and Dy(III) was realized. The THY:TOPO (1:1) also exhibited remarkable extraction capability for all three rare earth elements present Nd(III), Dy(III), and Pr(III) within the original scrap NdFeB magnet leachate at the optimized conditions. This study emphasizes the inherent advantages of formulating eutectic solvents by combining efficient extractants, thereby enhancing the efficiency of metal recovery processes. [ABSTRACT FROM AUTHOR]

A new complex [Dy(C5H7O2)3(C5H5NO)]2·2CHCl3 (1) has been synthesized by the reaction of pyridine-N-oxide with dysprosium (III) acetylacetonate in an n-heptane/chloroform mixture (1/20). X-ray data show that each dysprosium atom is chelate-like coordinated by three acetylacetonate ligands and the oxygen atom from two bridging molecules of pyridine-N-oxide, which unite the dysprosium atoms into a binuclear complex. Static (constant current) and dynamic (alternating current) investigations and ab initio calculations of the magnetic properties of complex 1 were performed. The complex was shown to exhibit a frequency maximum under alternating current. At temperatures above 10 K, the maximum shifts to a higher frequency, which is characteristic of SMM behavior. It is established that the dependence of ln(τ) on 1/T for the relaxation process is nonlinear, which indicates the presence of Raman relaxation mechanisms, along with the Orbach mechanism. [ABSTRACT FROM AUTHOR]

Correct selection of alloying elements is important for developing novel biodegradable magnesium alloys with superior mechanical and biological performances. In contrast to various reports on nutrient elements (Ca, Zn, Sr, etc.) as alloying elements of biomedical magnesium alloys, there is limited information about how to choose the right rare earth elements (REEs) as alloying elements of magnesium. In this work, 16 kinds of REEs were individually added into Mg, including Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Du, Ho, Er, Tm, Yb and Lu, to fabricate binary Mg-RE model alloys with different composition points. Under the same working history, comparative studies were undertaken and the impact of each kind of rare earth element on the microstructure, mechanical property, corrosion behavior and biocompatibility of Mg were investigated. The corresponding influence level for the 16 kinds of REEs were ranked. The results showed that the second phases were detected in some Mg-RE alloys, which were mainly composed of Mg 12 RE. By adding different REEs into Mg with proper contents, the mechanical properties of resulting Mg-RE binary alloys could be adjusted in wide range. The corrosion resistance of Mg-light REE alloys was generally better than Mg-heavy REE alloys. As for biocompatibility, Mg-RE model alloys showed no cytotoxic effect on MC3T3-E1 cells. The hemolysis rates of all experimental Mg-RE model alloys were lower than 5% except for Mg-Lu alloy model. In general, the addition of different REEs into Mg could improve its performance from different aspects. This work provides a better understanding on suitable REEs as alloying elements for magnesium, and the future R&D direction on biomedical Mg-RE alloys was proposed. In contrast to various reports on nutrient elements (Ca, Zn, Sr, etc.) as alloying elements of biomedical magnesium alloys, until now there is limited information about how to choose the right rare earth elements (REEs) as alloying elements of magnesium. In this work, comparative studies were undertaken by individually adding 16 kinds of REEs, including Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Du, Ho, Er, Tm, Yb and Lu, into Mg to fabricate binary Mg-RE model alloys, with different composition points, then the impact of each kind of rare earth element on the microstructure, mechanical property, corrosion behavior and biocompatibility of Mg under the same working history were investigated, and the corresponding influence level for the 16 kinds of REEs were ranked. This work provides a better understanding on suitable REEs as alloying elements for magnesium, and the future R&D direction on biomedical Mg-RE alloys was proposed. Image, graphical abstract [ABSTRACT FROM AUTHOR]

Sol-gel auto combustion technique has been adopted to prepare RE doped Mn–Ni–Zn ferrite systems following the stoichiometry Mn 0.1 Ni 0.7 Zn 0.2 RE 0.5 Fe 1.5 O 4 (RE = Dy, Ce, Sm and Er). The XRD patterns confirm the cubic spinel phase with the Fd3m space group and the lattice parameter and crystallite size were found to be in the range of 8.3874–8.4066 Å and 28.6–33.2 nm. The M − H data indicates the soft magnetic behaviour of present ferrite systems. The substitution of rare-earth ions in the spinel structure influences the superexchange interaction and in turn, affects the magnetic behaviour of present ferrite systems. The highest value of saturation magnetization equal to 41.2 emu/g was observed for the sample with a composition of Mn 0.1 Ni 0.7 Zn 0.2 Ce 0.5 Fe 1.5 O 4. For all the ferrite systems studied here the real part (ε ′) of complex permittivity is increasing with an increase in frequency while oscillatory nature can be found in the imaginary part (ε ″). The value of ε ′ found in the range of 5.421–5.856 at 8.2 GHz and it is 5.538–6.066 at 12.4 GHz. The value of ε ″ is in the range of 0.092–0.104 at 8.2 GHz while it is in between 0.042 and 0.105 at 12.4 GHz. A wavy nature can be seen in the real part (μ ′) of complex permeability whereas the imaginary part (μ ″) is decreasing for all compositions with the increase in frequency, but shows a weak resonance peak between 9 and 10 GHz. The value of μ ′ is in the range of 0.869–0.958 at 8.2 GHz and it is 0.903–0.925 at 12.4 GHz. The value of μ ″ fall in between 0.269 and 0.334 at 8.2 GHz and it is in the range of 0.059–0.068 at 12.4 GHz. The shielding studies for EMI revealed that the present systems are working as microwave absorbers. The total effective shielding for all ferrite systems is in the range of 33.31–36.09 dB 8.2 GHz while it is in between 32.74 and 34.98 dB at 12.4 GHz. Under the investigation of shielding performance, it is observed that all the RE doped Mn–Ni–Zn ferrites systems studied here can effectively suppress the electromagnetic interference in X-band frequency. The ferrite system with composition Mn 0.1 Ni 0.7 Zn 0.2 Ce 0.5 Fe 1.5 O 4 has shown a potential microwave absorber in X-band frequency. [ABSTRACT FROM AUTHOR]

In this work, new high-entropy RE2(Ce0.2Zr0.2Hf0.2Sn0.2Ti0.2)2O7 (RE2HE2O7, RE = La, Nd, Sm, Eu, Gd, Dy) ceramics were successfully prepared. RE2HE2O7 ceramics exhibited a pyrochlore–fluorite dual-phase structure. For Sm2HE2O7 ceramic, Ce4+ with larger ionic radius was enriched in the fluorite phase, Sn4+ and Ti4+ with smaller ionic radii were enriched in the pyrochlore phase, while Zr4+ and Hf4+ with medium ionic radii existed in both phases. Compared with YSZ materials, RE2HE2O7 ceramics exhibited a much lower glass-like thermal conductivity (1.19–1.68 W m−1 K−1, 100–900 °C) and comparable thermal expansion coefficients (8.67–10.85 × 10−6 K−1, 1200 °C). Furthermore, due to grain refinement caused by the competition of two phases, the Vickers hardness (10.29–13.85 GPa) of RE2HE2O7 ceramics is improved. The results indicate that dual-phase high-entropy RE2HE2O7 ceramics are promising candidate materials for the next generation of thermal barrier coatings. [ABSTRACT FROM AUTHOR]

The rare earth (RE = Eu, Sm, Dy, and Tb) ions doped La10Si6O27 nanophosphor was synthesized by a simple solution combustion method. The prepared La10Si6O27:RE3+ nanophosphors (LNPs) were subjected to diverse technical tools for exploring their structural, optical, morphological, and electrochemical features. The structural analysis using powder X-ray diffraction (PXRD) patterns revealed the hexagonal oxy apatite phase for LNPs with a crystallite size in the range of 25–50 nm, and the equivalent was affirmed by image analysis via transmission electron microscopy (TEM). Utilizing DRS data, the bandgap energy (Eg) values were recorded for LNPs. Cyclic voltametric (CV), electrochemical impedance spectroscopy (EIS), and sensor studies were performed using a modified carbon paste electrode of LNPs. The modified LNP electrodes were found to be highly effective in sensing paracetamol in acidic medium with a quick response time of 3 secs for sensing the drugs at 1 mM concentration. All the RE ions Eu3+, Sm3+, Dy3+, and Tb3+ (5 mol%)-doped LNPs exhibited the most promising electrochemical sensing characteristics. [ABSTRACT FROM AUTHOR]

In recent years, rare earth silicate compounds have attracted the extensive attention of researchers owing to their potential for applications in scintillation crystals in gamma ray or X-ray detectors, as well as in thermal or environmental barrier coatings. Large high quality crystals of three members of the rare earth monosilicates family of compounds, R 2 SiO 5 (with R = Dy, Ho, and Er), have been grown by the floating zone method, using a laser-diode-heated floating zone furnace. Crystal growths attempts were carried out using different parameters in order to determine the optimum conditions for the growth of these materials. The phase purity and the crystalline quality of the crystal boules were analysed using powder and Laue X-ray diffraction. Single crystal X-ray diffraction experiments were carried out to determine the crystal structures of the boules. The optimum conditions used for the crystal growth of R 2 SiO 5 materials are reported. The phase purity and high crystalline quality of the crystals produced makes them ideal for detailed investigations of the intrinsic physical and chemical properties of these materials. [ABSTRACT FROM AUTHOR]

The Dy–Al–Si ternary system has been experimentally studied, as the effect of the dysprosium addition on the constitution and topology of the liquidus surface, focusing on the (Al) rich part. The system has been investigated in a composition range of up to about 58 at% silicon. The alloys constitution and the liquidus surface projection have been determined by means of scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDXS), X-ray powder diffraction (XRPD), and differential thermal analysis (DTA). This work is part of a research framework on the properties and solid–liquid phase equilibria of the R Al–Si (R: rare earth) systems. These data, along with the ternary systems isothermal section, are needed to outline the design, plan, and development of new Al–Si-based alloys. In the Dy–Al–Si system, four primary crystallization fields have been experimentally detected: (Si), DyAlxSi(2−x) (orthorhombic form), Dy2Al3Si2 (Τ2), and DyAl(3−x)Six. The following three invariant equilibria have been identified: at 566 °C the ternary eutectic L ⇆ DyAl2Si2 + (Al) + (Si), at 630 °C the U1 L+ DyAl3 ⇆ Dy2Al3Si2 + (Al), and at 562 °C the U2: L+ Dy2Al3Si2 ⇆ DyAl2Si2 +(Al) reactions. A comparison with other known R Al–Si systems has been conducted. [ABSTRACT FROM AUTHOR]

New data on phase states and structural phase transitions in alloys Fe73Ga27 doped with Dy, Er, Tb, and Yb in an amount of about 0.5 at % are presented. Structural data were obtained in neutron diffraction experiments performed with high resolution and in continuous temperature scanning mode during heating to 850°C and subsequent cooling at a rate of ±2°C/min. It has been established that both the sequence of forming and disappearing structural phases and the final state of the alloy depend on the type of rare earth element. Phase transitions in the alloy with Dy are similar to those in the initial Fe73Ga27 alloy, excluding the final state. The procedure of doping with Er and Tb leads to the formation of disordered A1 and A3 phases instead of the L12 and D019 ordered close packed phases, respectively. In the case of doping with Yb, neither of the above phases is observed. The formation of the L60 (m-D03) and D022 tetragonal structural phases previously discovered in similar alloys by the electron diffraction method is not confirmed. [ABSTRACT FROM AUTHOR]

In this work, we investigated the potential of Eu3+/Dy3+-codoped Y2Sn2O7 fluorescent nanophosphors to visualize latent fingermarks. We prepared these nanophosphors with various doping concentrations by the conventional coprecipitation reaction. The crystal structure, morphology, luminescence properties, and energy transfer mechanisms were studied. The crystalline phase was characterized by X-ray diffraction and crystal structure refinement using the Rietveld method. XRD measurements showed that the samples crystallized in the pure single pyrochlore phase with few more peaks originated from secondary phases and impurities generated during phosphor production, and that Eu3+ ions occupied D3d symmetry sites. The average crystallite size after mechanical grinding was less than 100 nm for all compositions. The optical characterization showed that, when excited under 532 nm, the Eu3+/Dy3+-codoped Y2Sn2O7 samples' main intense emission peaks were located at 580–707 nm, corresponding to the 5D0→7Fj (j = l, 2, 3, and 4) transitions of europium. In fact, the 5D0→7F2 hypersensitive transition is strongly dependent on the local environment and was quite weak in Eu3+:Y2Sn2O7 at low Eu3+ doping levels. We found that the presence of Dy3+ as a codopant permitted enhancing the emission from this transition. The calculated PL CIE coordinates for the synthesized nanophosphors were very close to those of the reddish-orange region and only slightly dependent on the doping level. Various surfaces, including difficult ones (wood and ceramic), were successfully tested for latent fingerprint development with the prepared Eu3+/Dy3+-codoped Y2Sn2O7 fluorescent nanophosphor powder. Thanks to the high contrast obtained, fingerprint ridge patterns at all three levels were highlighted: core (level 1) islands, bifurcation, and enclosure (level 2), and even sweat pores (level 3). [ABSTRACT FROM AUTHOR]

In Tb-Dy-Fe alloy systems, Tb0.29Dy0.71Fe1.95 alloy shows giant magnetostrictive properties under low magnetic fields, thus having great potential for transducer and sensor applications. In this work, the lattice parameters of Tb0.29Dy0.71Fe1.95 compounds as a function of a magnetic field were investigated using in situ X-ray diffraction under an applied magnetic field. The results showed that the c-axis elongation of the rhombohedral unit cell was the dominant contributor to magnetostriction at a low magnetic field (0–500 Oe). As the magnetic field intensity increased from 500 Oe to 1500 Oe, although the magnetostrictive coefficient continued to increase, the lattice constant did not change, which indicated that the elongated c-axis of the rhombohedral unit cell rotated in the direction of the magnetic field. This rotation mainly contributed to the magnetostriction phenomenon at magnetic fields of above 500 Oe. The structural origin of the magnetostriction performance of these materials was attributed to the increase in rhombohedral lattice parameters and the rotation of the extension axis of the rhombohedral lattice. [ABSTRACT FROM AUTHOR]

Thermal stress (σ) plays a critical role in regulating the stability and durability of thermal barrier coatings (TBCs) during service. However, its measurements are limited due to technical challenges. Here, thermal stresses in RETaO 4 (RE = Nd, Sm, Eu, Gd, Tb, Dy, Ho, and Er) TBCs have been evaluated by a cross-scale model, integrating first-principles calculations and finite element simulations (FEM). The isobaric heat capacity, thermal expansion coefficients, density, Young's modulus, and Poisson's ratio of RETaO 4 as a function of temperature have been determined by the quasi-harmonic approach (QHA) and the quasi-static approach (QSA). Taking these properties as the input data of FEM, the σ of TBCs with RETaO 4 as ceramic coatings is estimated. It indicates that the maximum tensile stress exists at the ceramic and thermal-grown oxide coating interface. Notably, TBCs_NdTaO 4 exhibits the highest tensile stress, reaching up to 2093 MPa, while TBCs_GdTaO 4 has the lowest value at 1880 MPa. Furthermore, the key factors affecting σ are estimated using interpretable machine learning based on the decision tree algorithm. The RETaO 4 with small Poisson's ratio, strong electronegativity, small heat capacity, and thermal expansion coefficients is helpful to achieving low σ in TBCs. GdTaO 4 , YTaO 4 and (Ho 0.5 Er 0.5)TaO 4 emerge as more favorable options as ceramic layer due to their lower σ in TBCs. This present cross-scale model provides a successful tool for predicting σ and the reverse design of TBCs materials based on low σ in TBCs. [Display omitted] Abstract Graph: A multiscale evaluation method coupled with first-principles calculations, finite element simulations (FEM), and machine learning, which can be used for reverse design for thermal barrier coating. [ABSTRACT FROM AUTHOR]

The study reports the influence of rare-earth ion doping on the structural, magnetic, and magnetocaloric properties of ferrimagnetic Gd3−xRExFe5O12 (RE = Y, Nd, Sm, and Dy, x = 0.0, 0.25, 0.50, and 0.75) garnet compound prepared via facile autocombustion method followed by annealing in air. X-Ray diffraction (XRD) data analysis confirmed the presence of a single-phase garnet. The compound's lattice parameters and cell volume varied according to differences in ionic radii of the doped rare-earth ions. The RE3+ substitution changed the site-to-site bond lengths and bond angles, affecting the magnetic interaction between site ions. Magnetization measurements for all RE3+-doped samples demonstrated paramagnetic behavior at room temperature and soft-ferrimagnetic behavior at 5 K. The isothermal magnetic entropy changes (−ΔSM) were derived from the magnetic isotherm curves, M vs. T, in a field up to 3 T in the Gd3−xRExFe5O12 sample. The maximum magnetic entropy change ( − ∆ S M m a x ) increased with Dy3+ and Sm3+substitution and decreased for Nd3+ and Y3+ substitution with x content. The Dy3+-doped Gd2.25Dy0.75Fe5O12 sample showed − ∆ S M m a x ~2.03 Jkg−1K−1, which is ~7% higher than that of Gd3Fe5O12 (1.91 Jkg−1K−1). A first-principal density function theory (DFT) technique was used to shed light on observed properties. The study shows that the magnetic moments of the doped rare-earths ions play a vital role in tuning the magnetocaloric properties of the garnet compound. [ABSTRACT FROM AUTHOR]

Four new cyano-bridged DyIII-CrIII, DyIII-FeIII, HoIII-CrIII and HoIII-FeIII bimetallic coordination polymers were synthesized by the reaction of [Ln(H2dapsc)(H2O)4](NO3)3 (Ln = Dy, Ho); H2dapsc = 2,6-diacetylpyridinebis(semicarbazone)) with K3[M(CN)6] (M = Cr, Fe) in H2O, resulting in the substitution of two water molecules in the coordination sphere of rare earth by paramagnetic tricharged hexacyanides of Fe and Cr. The complexes are isostructural and consist of alternating [Ln(H2dapsc)(H2O)2]3+ and [M(CN)6]3− units linked by bridges of two cis-cyano ligands of the anion to form square-wave chains. The ac magnetic measurements revealed that the DyCr and DyFe complexes are field-induced single molecule magnets, while their Ho analogs do not exhibit slow magnetic relaxation. [ABSTRACT FROM AUTHOR]

Here we report the study temperature dependencies of the Seebeck coefficient, the electrical resistivity (T = 300–750 K), the total thermal conductivity (T = 300–973 K), and the thermoelectric figure of merit (T = 300–750 K) of ceramic samples of γ‐Ln0.8Yb0.2S1.5‐y (Ln = Gd, Dy) solid solutions. It was found that Yb3+ ions in γ‐Ln0.8Yb0.2S1.5‐y act as the promoters of higher crystallite nucleation rate during the formation of solid solutions. This results in the sample dispersion increase and the formation of the additional phonon scattering centers (dislocations and strain stresses along the crystallites semi‐coherent boundaries). These features of the real structure determined the low value of thermal conductivity of γ‐Ln0.8Yb0.2S1.5‐y solid solutions. The lowest electrical resistivity 20 μΩ m at 750 K and the thermal conductivity 0.58 W/m K at 973 K, the highest Seebeck coefficient 125 μV/K at 700 K and the maximum thermoelectric efficiency, ZT = 0.60 (at 770 K) were obtained for γ‐Dy0.8Yb0.2S1.5‐y. [ABSTRACT FROM AUTHOR]

In this paper, a detailed investigation with respect to the structural, cryogenic magnetic properties and magnetocaloric performances of RE 2 CuMnO 6 (RE = Gd, Dy, Ho and Er) double perovskite (DP) compounds has been performed. All the RE 2 CuMnO 6 compounds are confirmed to B -site disordered and crystallized in the GdFeO 3 -type structure (Pnma space group, N 62, oP20). The magnetic transition temperatures (T M) are found to be ~7.5 K for Gd 2 CuMnO 6 , ~12.1 K for Dy 2 CuMnO 6 , ~12.2 K for Ho 2 CuMnO 6 , and ~3.6 K for Er 2 CuMnO 6 , respectively. Moreover, for checking the magnetocaloric performances several vital parameters including -Δ S M max (peak value of magnetic entropy change, -Δ S M), TEC (3) (temperature averaged -Δ S M) and RCP (relative cooling powers) are evaluated to be 7.84, 7.73 J/kgK and 151.1 J/kg for Gd 2 CuMnO 6 , 5.69, 5.59 J/kgK and 180.9 J/kg for Dy 2 CuMnO 6 , 7.12, 7.05 J/kgK and 192.4 J/kg for Ho 2 CuMnO 6 , as well as 9.92, 9.60 J/kgK and 195.9 J/kg for Er 2 CuMnO 6 under the magnetic field change Δ H = 5 T, respectively. [ABSTRACT FROM AUTHOR]