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We report the real-valued static and complex-valued quasi-static anisotropic permittivity parameters of rare-earth scandate orthorhombic single crystal GdScO3 (GSO), TbScO3 (TSO), and DyScO3 (DSO). Employing continuous-wave terahertz spectroscopy (0.2–1 THz), the complex permittivity was extracted using an anisotropic ambient-film-ambient model. Data obtained from multiple samples of the same oxides and different surface cuts were analyzed simultaneously. The zero-frequency limit of the modeled data indicates that at room temperature the real part of the dielectric tensor components for GSO are ɛa = 22.7, ɛb = 19.3, and ɛc = 28.1; for DSO, ɛa = 20.3, ɛb = 17.4, and ɛc = 31.1; and for TSO, ɛa = 21.6, ɛb = 18.1, and ɛc = 30.3, with a, b, and c crystallographic axes constituting the principal directions for the permittivity tensor. These results are in excellent agreement with expectations from theoretical computations and with scarcely available data from previous experimental studies. Furthermore, our results evidence a noticeable attenuation, which increases with frequency, and are very significant especially at the higher frequency end of the measurement and along the c-direction in all samples. We suggest the attenuation is most likely caused by the onset of absorption due to long-wavelength active optical phonon modes. These results are important for electronic and potential sub-terahertz applications (e.g., quarter-wave plate) benefiting from the large index contrast along different directions in these materials. [ABSTRACT FROM AUTHOR]

Rare-earth doped materials are of immense interest for their potential applications in linear and nonlinear photonics. There is also intense interest in sub-nanometer gold clusters due to their enhanced stability and unique optical, magnetic, and catalytic properties. To leverage their emergent properties, here we report a systematic study of the geometries, stability, electronic, magnetic, and linear and nonlinear optical properties of Au5RE (RE = Sc, Y, La–Lu) clusters using density-functional theory. Several low-energy isomers consisting of planar or non-planar configurations are identified. For most doped clusters, the non-planar configuration is energetically favored. In the case of La-, Pm-, Gd-, and Ho-doped clusters, a competition between planar and non-planar isomers is predicted. A distinct preference for the planar configuration is predicted for Au5Eu, Au5Sm, Au5Tb, Au5Tm, and Au5Yb. The distinction between the planar and non-planar configurations is highlighted by the calculated highest frequencies, with the stretching mode of the non-planar configuration predicted to be stiffer than the planar configuration. The bonding analysis reveals the dominance of the RE-d orbitals in the formation of frontier molecular orbitals, which, in turn, facilitates retaining the magnetic characteristics governed by RE-f orbitals, preventing spin-quenching of rare earths in the doped clusters. In addition, the doped clusters exhibit small energy gaps between frontier orbitals, large dipole moments, and enhanced hyperpolarizability compared to the host cluster. [ABSTRACT FROM AUTHOR]

The article presents the study of the magnetocaloric effect (MCE) for the rhombohedral Laves phase of Pr 2 Rh 3 Ge, which shows a magnetic order below T C = 8.5 K. We have established that the compound exhibits a continuous second-order type of transition which was demonstrated and confirmed by several different techniques, mainly by analyzing universal curves of normalized entropy change as a function of scaled temperature. The observed MCE, in our opinion, is a consequence of an indirect exchange coupling between the magnetic sublattices of the rare earth ions, which, however, does not exclude the potential contribution of sublattice-containing transition metals. In this paper, the procedure to evaluate the MCE from magnetization and specific heat data is described. As a result, important parameters such as the isothermal magnetic entropy change (Δ S M), adiabatic temperature change (Δ T a d ), relative cooling power (RCP), and the temperature averaged entropy change (TEC) were determined. The highest values of − Δ S M , Δ T a d , and RCP for a field change (Δ μ 0 H) of 5 T at T C are 5.96 J/kg K, 3.87 K, and 72.62 J/kg, respectively. These results obtained for Pr 2 Rh 3 Ge seem to be, however, low compared to the values obtained for the rhombohedral Laves phases, belonging to the group of ternary germanides RE 2 Rh 3 Ge containing heavy rare earth metals (RE = Gd, Tb, Ho, and Er). Nevertheless, we believe that the results presented in this work extend and complement the current knowledge on the magnetocaloric properties of this family of materials. [ABSTRACT FROM AUTHOR]

Magnetocaloric properties of TbCrO3 and TmCrO3 are reported and compared with those of the previously reported rare-earth chromites RCrO3 (R = Gd, Dy, Ho, and Er) and other perovskite-type oxides. The samples of TbCrO3 and TmCrO3 in this work were synthesized using a citrate gel combustion technique, and their magnetic properties were investigated and compared with those reported previously on RCrO3 (R = Gd, Dy, Ho, and Er). The Cr3+–Cr3+ ordering temperatures were found to strongly depend on the ionic radii of the rare-earth. By fitting the dc magnetization data with modified Curie–Weiss law including the Dzyaloshinsky–Moriya antisymmetric exchange interaction (D) and the symmetric exchange constant Je, spin canting angles (α) were obtained. In general, α was found to increase with the decreasing ionic radii of R3+ in RCrO3. The magnetocaloric properties investigated included the magnetic entropy change (−ΔS) for a given change in magnetic field (ΔH), the corresponding adiabatic temperature change (ΔTad), and their relative variations (ΔTad/ΔH) and (−ΔS/ΔH). It is observed that for RCrO3, (−ΔS) measured in the vicinity of the ordering temperature of R3+–R3+, varies almost as G2/3 where G is the de Gennes factor. Among RCrO3, GdCrO3 shows the largest value of (−ΔS/ΔH), because of its largest G factor and its magnitudes of (ΔTad/ΔH) and (−ΔS/ΔH) compare well with the reported values for the perovskites GdFeO3 and EuTiO3. These comparisons presented here provide useful information on the potential use of these materials in magneto-refrigeration technology. [ABSTRACT FROM AUTHOR]

We report the structure and physical properties of a new rare-earth (RE) high-entropy boride (HEB) (Dy 0.2 Ho 0.2 Er 0.2 Tm 0.2 Lu 0.2)(Rh 0.85 Ru 0.15) 4 B 4. The as-cast HEB consists of a highly crystallized, body-centered-tetragonal phase (I 4 1 / a c d , a = 7.460 Å and c = 14.860 Å); here, all the RE elements share the same crystallographic site and are distributed uniformly on both macroscopic and microscopic scales. At high temperature, the HEB shows a paramagnetic behavior with a large effective moment p eff yet it becomes a bulk superconductor upon cooling below 6.0 K. Remarkably, a peculiar cocktail effect of properties is observed: while the lattice parameters, T c and p eff of the HEB agree reasonably well with the compositional averages of the individual pseudo-ternary counterparts, the increased RE mixing entropy tends to suppress the superconductivity even without the magnetic exchange interactions, and a reentrant resistive transition is induced at magnetic fields above 0.8 T. Our results indicate that the high-entropy design of the RE sublattice is a viable way to tune the electrical and magnetic properties in RE intermetallics. [ABSTRACT FROM AUTHOR]

Dy3+, Eu3+ co-doped glass ceramics (GCs) containing SrMoO 4 crystalline phase were prepared by melt-curing-crystallization method. The most favorable heat treatment conditions for the glass ceramics were found to be 610 °C/2 h by differential scanning calorimetry (DSC), ultraviolet spectrophotometer (UV–Vis), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The best doping concentrations of Dy3+ and Eu3+ in this glass ceramic were 0.8 % and 0.6 %, concentration quenching caused by dipole-dipole interactions occurs when the content of rare earth ions in GCs continues to increase. The chromaticity coordinates of the Dy3+- Eu3+ co-doped glass ceramics changed from cool white light to warm white light with the addition of Eu3+ concentration. At the optimal doping concentration (0.8 % Dy3+-0.6 % Eu3+), the chromaticity coordinate of glass ceramics is (0.3972, 0.3331), and the related color temperature is 3047 K. The luminescence intensity can still reach about 80 % of room temperature at 180 °C, and its thermal quenching activation energy is 0.233 eV. This suggests that glass ceramics have excellent thermal stability. After adding an appropriate amount of Li+, the crystalline phase of the glass ceramics remained unchanged and the luminous intensity of the glass ceramics increased by a factor of about 1.4 in the same environment. The thermal quenching activation energy of the glass ceramic doped with 0.2 % Li+-0.8 % Dy3+-0.6 % Eu3+ was 0.344 eV. The experimental results indicate that GCs has potential application prospects in the field of solid-state lighting. [ABSTRACT FROM AUTHOR]

As the flight speed of aircraft continues to increase, high-temperature wave-transparent materials for radomes or antenna windows face great challenges. The shortage of new high-performance wave-transparent materials is limiting the improvement of aircraft performance. In this work, dielectric and mechanical properties of RE 2 SiO 5 (RE = Ho, Er, Tm, Yb, and Lu) were investigated to explore their application as high-temperature wave-transparent materials. RE 2 SiO 5 (RE = Ho, Er, Tm, Yb, and Lu) ceramics possess relatively low dielectric constant and it is insensitive to the RE species. For the dielectric loss, they gradually decrease as the radius of rare earth ions decreases. In addition, RE 2 SiO 5 (RE = Ho, Er, Tm, Yb, and Lu) possesses good mechanical properties with high hardness and relatively low reduced modulus, and hardness is insensitive to the rare earth ion radii while the reduced modulus increases with the RE3+ ions radius decreases. They are larger than those of fused silica, the most used traditional high-temperature wave-transparent material. The results provide important material selection and optimization guidelines for RE 2 SiO 5 as the candidate for next-generation high-temperature wave-transparent materials. [ABSTRACT FROM AUTHOR]

Multi-modal strategies for optical information storage have received a lot of attention to meet the increasing security requirements. In this case, long persistent luminescence (LPL) phosphors with different dopant ions were obtained by introducing Dy3+ and Ho3+ ions into the BaSi 2 O 5 :Eu2+ phosphor to adjust the distribution and depth of the trap centers. The generation of the pure phase BaSi 2 O 5 was confirmed by X-ray diffraction (XRD) and XRD Rietveld refinement. The peak emission of BaSi 2 O 5 : Eu2+ phosphor is about 500 nm with 313 nm excitation. Both BaSi 2 O 5 : Eu2+, Dy3+, and BaSi 2 O 5 : Eu2+, Ho3+ phosphors exhibit emission characteristics of Eu2+ ions. The trap depths of the three phosphors are different by Gaussian fitting of thermoluminescence (TL) curves, and the depth of BaSi 2 O 5 : Eu2+, Dy3+ phosphor can reach 1.070 eV. Typically, the flexible luminescent film based on BaSi 2 O 5 : Eu2+ phosphor can be written optical pattern using 365 nm ultraviolet (UV) light, such as "DL" and "fireworks" patterns, and subsequently read out by thermal or infrared light stimulus. Further, a strategy for encryption and decryption of dynamic optical information in Morse code has been developed using BaSi 2 O 5 : Eu2+, BaSi 2 O 5 : Eu2+, Dy3+, and BaSi 2 O 5 : Eu2+, Ho3+ phosphors, indicating the prospective use in optical information security. [ABSTRACT FROM AUTHOR]

The present study covers the fabrication of flexible piezoelectric nanogenerators and their application towards sustainable power generation. The rod-like structure of erbium-doped ZnO (EZ) nanoparticles prepared by the hydrothermal synthesis route was successfully incorporated inside the polyvinylidene fluoride (PVDF) matrix using the solution casting method. Solution casting is an easy and cost-effective method for fabricating laminated, thin, flexible and lightweight EZ-PVDF nanocomposite films. The formation of the desired crystallographic phase of EZ-PVDF nanocomposite films and the presence of rod-like EZ nanoparticles inside the PVDF matrix were confirmed using X-ray diffraction and FESEM. The enhancement of the β-phase fraction of the EZ-PVDF nanocomposite films as compared to bare PVDF was estimated using FTIR spectroscopy. The presence of a ferroelectric phase in the EZ-PVDF nanocomposite films was found due to the formation of a large area of interfaces between the EZ nanoparticles and the PVDF matrix. The maximum polarizations of 0.00696 μC cm-2 and 0.00683 μC cm-2 for two samples (EZP1 and EZP2, respectively) were observed at an electric field of 1.25 kV cm-1. The piezoelectric voltages were observed at relatively low frequencies for both nanocomposite films. The maximum piezoelectric voltages of 18.9 V and 15.5 V were observed at a 1 Hz frequency for EZP1 and EZP2, respectively. The output piezoelectric current of 16.88 mA and the maximum power density of 7773.68 W m-3 for EZP1 ensure its potential as an efficient piezoelectric nanogenerator with greater efficiency than those reported previously in published articles. The change in the piezoelectric voltage response of the nanocomposite films as a function of mechanical movement of human external body parts renders them the most suitable candidate for human--machine interfacing (HMI) applications, such as bending sensors and human motion sensors. [ABSTRACT FROM AUTHOR]

A series of bimetallic rare-earth complexes {[μ-η1:(μ-η1:η1):η1-1-(2-C5H4N)-3-(2-C7H4NS)C8H4N]RE(CH2SiMe3)2}2 (RE = Y(7a), Er(7b), Yb(7c), Lu(7d)) were synthesized by treatment of rare-earth metal trialkyl complexes RE(CH2SiMe3)3(THF)2 with one equiv. of the proligand 1-(2-C5H4N)-3-(2-C7H4NS)C8H5N (6) in good isolated yields. Complex 7c can be converted to the divalent rare-earth metal complexes (η4:σ:κ1-L)2YbII [L = 1-(2-C5H4N)-3-(2-C7H4NS)C8H4N(CHSiMe3)] (8) at elevated temperature in toluene solution. Complexes 7a, 7d and 8 were characterized by NMR spectroscopy. Additionally, the yttrium (7a), erbium (7b) and lutetium (7d) complexes exhibited high activity in the polymerization of 2-vinylpyridine with isotactic selectivity and high molecular weight. [ABSTRACT FROM AUTHOR]

Six multi-component rare earth phosphate materials were prepared by chemical co-precipitation, which are (La 0.2 Nd 0.2 Sm 0.2 Eu 0.2 Gd 0.2)PO 4 , (La 0 · 2 Ce 0.2 Nd 0.2 Sm 0.2 Eu 0.2)PO 4 , (Ce 0.2 Nd 0.2 Sm 0.2 Eu 0.2 Gd 0.2)PO 4 , (La 0.5 Nd 0.5)PO 4 , (La 0.5 Gd 0.5)PO 4 and (Nd 0.5 Gd 0.5)PO 4. Hot corrosion behavior tests were conducted in molten V 2 O 5 salt at 900 °C and 1000 °C for 20 h and 40 h, respectively. The results show that the corrosion temperature and the heat treatment time have little effect on the type of corrosion products. Among these materials prepared in this study, the material containing Gd element and the material without Gd element exhibit different hot corrosion behavior. For the multi-component rare earth phosphate materials containing Gd element, the corrosion product is ReVO 4 (Re Sm, Eu, Gd) xenotime, and a reaction layer is formed on the surface of the bulk. For the multi-component rare earth phosphate materials without Gd element, the corrosion product is Re(P,V)O 4 (Re La, Ce, Nd) solid solution and the amount of product is very small, the corrosion reaction is extremely weak and no reaction layer is formed. Although the molten salt mainly penetrates, the original structure of the bulk has not been damaged, which indicates that its hot corrosion resistance is good. The hot corrosion mechanisms of these six multi-component rare earth phosphates are studied based on the crystallographic characteristics of rare earth phosphates/vanadates. [ABSTRACT FROM AUTHOR]

The reactions of rare earth elements (REEs) with refractory materials significantly affect their effective concentrations and inclusion modifications in molten steel. This study investigated the influence of steel-refractory reactions on the modification of inclusions in lanthanum-, cerium-, and yttrium-added steels utilizing three types of commonly used crucibles as smelting vessels. Steel-refractory reactions were found to strongly affect inclusions with different outcomes for smelting in MgO, Al 2 O 3 , and MgO·Al 2 O 3 crucibles. The RE-crucible reactions affected the evolution and size of inclusions in molten steel by influencing the content of [Mg] and [Al]. The RE-MgO crucible reactions increased [Mg] content, leading to more MgO inclusions and a smaller average size. The RE-Al 2 O 3 crucible reactions increased [Al] content, resulting in more REAlO 3 inclusions and a bigger average size. The reactions of La, Ce, and Y with MgO·Al 2 O 3 crucibles had varying effects on the evolution of inclusions. La and Ce selectively eroded the crucible, mostly reacting with the Al 2 O 3 component and generating REAlO 3 inclusions. In contrast, the slow reaction rate of Y with the crucible and the formation of the dense Y 2 O 3 layer at the steel/crucible interface made it react almost simultaneously with both MgO and Al 2 O 3 components, and the modification of inclusions was dominated by [Mg] rather than [Al]. The above conclusions provided more information on how the reactions between rare earth elements and refractory materials affected inclusions in rare earth steels during smelting. They also enriched the theory of inclusion control in steel and offered new controlling strategies. [ABSTRACT FROM AUTHOR]

Bioactive glasses are renowned for their applications in dentistry, serving as restorative materials, dental adhesives, intracanal medicaments, and agents for enamel remineralization. Niobium pentoxide (Nb 2 O 5) is employed in dental adhesive resins and orthodontic adhesives, offering radio-pacifying properties essential for dental materials. Samarium oxide (Sm 2 O 3) emerges as a potential additive in aesthetic restorative dental ceramics and resins, enhancing the natural fluorescence of teeth. In this study Nb 2 O 5 and Sm 2 O 3 -doped (1, 3, and 5 wt%) 13–93 bioactive glass particles were synthesized via the sol-gel method, tailored for dental implementations. We conducted a comprehensive analysis of the physical, structural, and optical properties of the resultant glass powders. Additionally, their in vitro bioactivity and ionizing radiation shielding characteristics were rigorously evaluated. The results indicate that Sm3+ ions preserve the amorphous nature of the silicate glasses, while Nb5+ incorporation leads to the crystallization of the T-Nb 2 O 5 phase. Bioactivity assays across three physiological fluids—simulated body fluid, α-minimum essential medium, and phosphate-buffered saline, demonstrated the ability of doped glasses to facilitate hydroxyapatite layer formation, with the most pronounced bioactivity observed in phosphate-buffered saline immersed samples. Furthermore, radiation shielding simulations reveal that the addition of Nb 2 O 5 and Sm 2 O 3 enhances the ionizing radiation attenuation capabilities of the glasses, a property that holds significant promise for protecting against radiation in dental radiology. It can be concluded that the dual functionality of Nb5+ and Sm3+-doped bioactive glasses, which may revolutionize restorative dental practices and offer improved protection in radiological applications. [ABSTRACT FROM AUTHOR]

A novel (Nd 0.2 Sm 0.2 Eu 0.2 La 0.2 Dy 0.2) 2 Gd 0.5 Yb 0.5 TaO 7 high-entropy oxide was successfully prepared through the sol–gel and high-sintering technique. The synthesized powder has a single-lattice structure, and the bulk sample has sole pyrochlore-type lattice. Given the particularity structure and the high concentration of oxygen vacancies caused by ion doping, the (Nd 0.2 Sm 0.2 Eu 0.2 La 0.2 Dy 0.2) 2 Gd 0.5 Yb 0.5 TaO 7 's thermal conductivity (1.385–1.187W·m−1·K−1) is lower than those of (La 1/6 Nd 1/6 Yb 1/6 Y 1/6 Sm 1/6 Lu 1/6) 2 Ce 2 O 7 , Sm 2 Zr 2 O 7 , and Sm 2 Ce 2 O 7. Its excellent phase stability and suitable coefficient of thermal expansion (～10.80 × 10−6 K−1, ～1200 °C) also indicate its potential as candidate oxide for thermal barrier coatings. [ABSTRACT FROM AUTHOR]

Rare-earth titanate pyrochlores have attracted significant attention for their unique magnetic frustration; however, research on the origin of low-temperature dielectric dispersion and the relationship between dielectric properties and structure lags far behind. Here, by systematically investigating the dielectric properties of representative rare-earth titanates R2Ti2O7 (R = La, Nd, Sm, Er, Yb, and Lu), we demonstrate that R2Ti2O7 with a cubic pyrochlore structure exhibits low-temperature dielectric dispersion behavior, while the other compounds with a monoclinic perovskite-like layered structure possess no dispersion behavior but excellent temperature-stable dielectric property. The dielectric dispersion in cubic pyrochlores arises from the structural distortion. Furthermore, the existence of structural distortion is affirmed by the anomalous phonon softening of A1g Raman mode around the dielectric dispersion temperature, and the origin of the structural distortion is attributed to anharmonic phonon–phonon interactions induced by intrinsic vacant oxygen at Wyckoff 8a sites. In addition, with increasing ionic radius from R = Lu to Sm, the increased lattice parameter leads to varied bond length and bond angle of Ti-O(1)-Ti, which strengthens the local lattice distortion of TiO(1)6 octahedra and thus enhances diffusion degree of dielectric dispersion. On the other hand, the absence of intrinsic vacant oxygen site hardly gives rise to the local structural distortion and thus no dielectric dispersion in monoclinic R2Ti2O7. Our work not only clarifies the mechanism of dielectric dispersion but also gives a comprehensive perspective on the structure–property relationship of rare-earth titanates R2Ti2O7, and thus lays a solid foundation for further work on related materials. [ABSTRACT FROM AUTHOR]

Cu serves as a promising electrocatalyst for converting CO2 into valuable C2 products in CO2 reduction reactions (CO2RR). However, instability in CO* formation is crucial for CO2 adsorption‐ desorption still remains a challenge under reduction conditions. This study explores the impact of lanthanide oxide, particularly CeO2, on Cu‐based catalytic performances. By leveraging Ce's distinctive electronic structure, CO* species are stabilized during the reaction in CeO2─Cu2O, resulting in exceptional catalytic performance for CO2 electroreduction to C2 products. Hybridizing CeO2‐Cu2O with graphene aerogel enhances electrochemical active surface area and CO2RR efficiency. The resulting CeO2─Cu2O(10%)/GA electrocatalyst exhibits a remarkable faradaic efficiency for C2 products, exceeding 62%, alongside exceptional stability over 80 h with wide potential window (−0.8 to −1.2 V) using a H‐cell. Systematic investigations elucidate the intricate interplay between surface properties and catalytic activity. Furthermore, a solar cell‐ powered CO2 reduction system demonstrates consistent performance (−27.8 mA cm−2 at 3.46 V) under solar radiation of ≈100 mW cm−2, showcasing outstanding stability with nearly 100% retention over 4 h of continuous illumination. In short, by harnessing catalytic and electronic effects, this innovation advances the development of electrocatalysts with heightened CO2‐to‐C2 selectivity, bridging fundamental research with technological innovation to tackle critical global challenges. [ABSTRACT FROM AUTHOR]

Potassium sodium niobate (KNN)‐based piezoelectric ceramics have emerged as a promising alternative to lead‐based systems due to their exceptional properties. While extensive research has focused on improving the electrical properties of KNN‐based ceramics through doping and processing optimization, the concurrent investigation of their mechanical properties has been lacking. This study presents a comprehensive analysis of the mechanical and electrical properties of KNN‐based lead‐free piezoceramics doped with various transition metal oxides and rare earth oxides, based on substantial experimental data. Our findings reveal that the as‐sintered KNN‐based ceramics exhibit not only outstanding electrical properties but also remarkable mechanical robustness compared to conventional toughened lead zirconate titanate (PZT)‐based ceramics. These exceptional electrical and mechanical properties are attributed to the micro‐scale and atomic‐scale structure of the modified KNN‐based ceramics, characterized by a highly condensed structure, an inhomogeneous distribution of nano‐domain structure, and the presence of amorphous intergranular films at grain boundaries. [ABSTRACT FROM AUTHOR]

Radiative cooling pigments offer new opportunities for sustainable carbon neutrality as zero‐energy and zero‐pollution functional materials. However, it is a challenge to prepare inorganic yellow pigments simultaneously with environmentally friendly, high color value, and weather resistance. In this study, a series of alkali metal‐doped γ‐Sm2S3 yellow pigments with near‐infrared reflectance were synthesized. The doping of alkali metal ions reduced synthesis temperature of Sm2S3 from 1300°C to 1000°C. The change in energy band structure induced by alkali metal doping allows the products to exhibit modifiable colors. Typical γ‐[Na]‐Sm2S3 pigment powders have a high near‐infrared reflectance and impressive colors (b* = 78.6, C* = 77.6). Furthermore, colored films made by prepared yellow powders with polyvinylidene fluoride in certain ratios had high near‐infrared reflectance and excellent environmental weathering, resulting in an effective cooling of 4–8°C in outdoor experiments. This work expands the range of options for energy‐efficient building and yellow colorant. [ABSTRACT FROM AUTHOR]

This work used a one-step calcination process to prepare g-C3N4 composites with varying Y2O3 loading. XRD, TEM, and XPS verified the structure and morphology of the composite photocatalyst, and its photoelectrochemical and hydrogen production performance were studied. According to the experimental results, it is found that the composite structure between Y2O3 and g-C3N4 effectively suppresses the photoelectron–hole complex and enhances the photocatalytic hydrogen production properties of g-C3N4. Under the irradiation of a 300 W xenon lamp, YCN-3 had superior photocatalytic hydrogen generation performance, achieving a rate of 1079.61 μ mol g−1 h−1, which was 2.3 times greater than that of g-C3N4 in its unmodified state. After three consecutive photocatalytic operations, satisfactory stability and reusability were obtained. Finally, the possibility of a mechanism for the photocatalytic charge transfer pathway is discussed, which provides an effective way for g-C3N4 photocatalytic hydrogen production. [ABSTRACT FROM AUTHOR]

NdFeB magnetic materials are the most commonly used rare earth magnets. In the production and processing of the NdFeB magnetic materials, it is necessary to conduct quality control on crude samples of magnetic materials to reduce production costs. Laser induced breakdown spectroscopy (LIBS) is a technique to obtain the spectrum of elements by exciting plasma on the surface of the sample with a high energy laser. An LIBS rare-earth magnet on-line measuring instrument for crude sample detection of magnetic materials is designed and developed. The instrument meets the requirements for product quality control in workshop production. The spectra of 7 kinds of NdFeB crude material samples were obtained by the LIBS instrument. To improve the classification accuracy, the algorithm in the instrument supporting software was used. Appropriate stoichiometric methods were selected, and a sliding window minimum removal base method was independently designed to further optimize the classification accuracy. The optimal ratio was determined by discussing the proportion of data sets, and the accuracy and stability were compared by cross-validation. Finally, stoichiometric method parameters were optimized. The overall optimization improves the classification accuracy from 87.14% to 99.05%. It is verified that the LIBS rare earth magnet online measuring instrument can effectively classify and detect NdFeB rare earth magnets, providing a fast, convenient, accurate and economical testing method for quality control in magnetic material workshops [ABSTRACT FROM AUTHOR]

This study delves into the impact of substituting Nd 2 O 3 for Na 2 O in Barium–Boron-Phosphate glasses, aiming to enhance their mechanical strength, optical characteristics, and radiation shielding efficacy. Glasses with a composition of 50B 2 O 3 + 20P 2 O 5 + 20BaO + (10-x)Na 2 O + xNd 2 O 3 (x = 0, 1, 2, 3, 4 mol%) were synthesized and characterized. The findings indicate that as the Nd/Na ratio increases, the density of the glass also rises within the range of 3.77–4.23 g/cm3. Moreover, the addition of Nd leads to notable alterations in the optical characteristics of the resulting glasses. Specifically, there is a shift observed in the UV absorption edges, coupled with a noticeable increase in absorption at visible wavelengths. Moreover, Nd 2 O 3 addition reduced the Urbach energy (from 0.6018 to 0.2239 eV for Nd0-Nd4) and the optical band gap indicating improved electronic structure and decreased disorder. The mechanical properties studied using the Makishima-Mackenzie model show As the replacement ratio of Nd 2 O 3 increases, there is a noticeable improvement in the glass's mechanical robustness. Importantly, Glasses with high Nd/Na ratio in their composition exhibit enhanced radiation shielding capabilities, evidenced by increased mass attenuation coefficients and effective removal cross-sections for photons and fast neutrons, respectively. These findings suggest that Nd 2 O 3 -doped glasses offer a promising pathway for developing superior radiation shielding materials with tailored properties for diverse applications in nuclear facilities, medical devices, and space exploration equipment. [ABSTRACT FROM AUTHOR]

Rare earth niobate Re 3 NbO 7 (Re=Rare earth element) possesses ultra-low thermal conductivity for application as thermal barrier coatings (TBCs). However, Re 3 NbO 7 with large rare earth ion radius (Re La, Nd, Sm) exhibits both low temperature phase transition and poor facture toughness which is detrimental to the durability of the coatings. In this work, an effective method was proposed to solve those problems by doping. Considering the low-temperature phase transition at about 340K, La 3 NbO 7 is selected as representative material. In order to suppress phase transition, Y3+ with relatively smaller ionic radius is used as a doped ion, and (La 1- x Y x) 3 NbO 7 (x = 0.0,0.1,0.3,0.5) were prepared and investigated. It is shown that, low temperature phase transition of La 3 NbO 7 is effectively suppressed due to Y3+ doped. Facture toughness is increased significantly from 0.5 to 2.3 MPa m1/2 with the increase of doping concentration. Furthermore, the Vickers hardness is also improved by doping. Considering the phase stability and ultra-low thermal conductivity, (La 1- x Y x) 3 NbO 7 solid solution (x = 0.5) maybe promising candidates for high temperature thermal insulation materials such as TBCs, thermoelectric materials, etc. [ABSTRACT FROM AUTHOR]

The inherent brittleness and uniform coloration of Si 3 N 4 materials have traditionally limited their applicability. In this study, colored Si 3 N 4 ceramics were synthesized utilizing α-Si 3 N 4 powder, a ternary mixture of sintering additives, and rare earth oxides (Eu 2 O 3 , Dy 2 O 3). The study focused on assessing the influence of varying Dy 2 O 3 content and holding time on the coloration, mechanical properties, and electromagnetic shielding properties of Si 3 N 4 ceramics. The incorporation of Eu 2 O 3 induced a color shift from gray to yellow-green, while the addition of Dy 2 O 3 facilitated the regulation of brightness in yellow-green Si 3 N 4 ceramics. The results reveal that both hardness and bending strength decreased with prolonged holding time, correlating with changes in sample density. The addition of rare earth oxides can effectively improve the fracture toughness of the Si 3 N 4 ceramics. Specifically, under conditions of 45 min holding time, 2%SED exhibited the highest fracture toughness at 8.45 MPa·m1/2. This enhancement can be primarily attributed to extended retention time, resulting in increased β- Si 3 N 4 phase content, improved fracture energy absorption, and a larger aspect ratio. The introduction of Eu 2 O 3 and Dy 2 O 3 did not significantly alter the electromagnetic shielding properties of Si 3 N 4 ceramics. This study offers novel pathways for the application of Si 3 N 4 ceramics in emerging fields. [ABSTRACT FROM AUTHOR]

The present work includes the use of effective strategy to improve the photocatalytic degradation activity of CdAl 2 O 4 via dopant assimilation to enhance the bandgap energy (E g) and to influence the light-sensitive activity of this spinel mixed oxide. In this study, CdAl 2 O 4 (CA), Mg–CdAl 2 O 4 (MCA), and Tb-doped Mg–CdAl 2 O 4 (TMCA) were fabricated by the facile co-precipitation route and an ultra-sonication approach was used to prepare a composite of Tb-doped Mg–CdAl 2 O 4 with MXene (TMCA@MXene). The obtained results from UV–Visible analysis deduce that there is an increase in E g of MCA (2.51 eV) and TMCA (2.67 eV) as compared to pure CA (2.45 eV) which follows the quantum confinement effect accompanying the decrease in crystallite sizes of doped samples as compared to CA. The significant increase in bandgap energy of TMCA is due to the confinement of electrons in a small area and also due to the conversion of continuous energy levels into discrete energy levels. Moreover, UV–Visible spectroscopic analysis was made to evaluate the catalytic performance of fabricated photocatalysts against harmful organic pollutants. The photocatalytic study showed that the co-doped CdAl 2 O 4 (TMCA) is a better photocatalyst than MCA and CA for the degradation of selected pollutants. Among all synthesized catalysts i.e. CA, MCA, TMCA, and TMCA@MXene, the highest photocatalytic activity was shown by MXene based nanocomposite. TMCA@MXene showed ∼86 % degradation of Rhodamine B (RhB) and 79.6 % degradation of Aspirin (acetylsalicylic acid). The outstanding photocatalytic efficacy of TMCA@MXene could be accredited to the quantum confinement effect produced by co-doping of alkaline earth metal (Mg+2) and rare earth metal (Tb+3) and large surface area, high conductivity, and excellent light harvesting capability provided by MXene sheets. Hence, TMCA@MXene could be an effective photocatalyst in future for the removal of toxic organic pollutants. [ABSTRACT FROM AUTHOR]

Rare earth from a newly discovered sedimentary rare earth ore (SREO) in Guizhou Province, China, was extracted through ammonium sulfate ((NH4)2SO4) activated roasting and leaching with sulfuric acid. The phase changes and reaction mechanism during the roasting process were explored through thermodynamic analysis, XRD, thermogravimetric analysis and scanning electron microscopy. When roasted at 650°C, first, the layered structure of kaolinite was destroyed by the reaction between (NH4)2SO4 with the SREO. Meanwhile, it is conducive to the reaction of rare earth minerals with (NH4)2SO4 to produce soluble rare earth sulfate. Second, the surface of the roasted product is loose, which makes it easier for sulfuric acid to erode into the ore. Therefore, the leaching rate of rare earth elements (REEs) improved after acid leaching. Under the optimized reaction conditions, specifically, a roasting temperature of 650°C, an (NH4)2SO4 to SREO mass ratio of 2.5:1, a roasting time of 1 h, a leaching temperature of 80°C, a leaching time of 2 h, an acid concentration of 5 mol/L, and a liquid-to-solid ratio of 9:1 (mg/L), the leaching rate of REEs reached 90.05%, 18.57% higher than that of roasting without (NH4)2SO4 addition. [ABSTRACT FROM AUTHOR]

The South Eastern Desert (SED) of Egypt is one of the most promising areas in Egypt; it is widely explored for exploring the rare earth elements (REEs) and uranium-bearing ores. It is a main part of the Arabian-Nubian Shield (ANS). Therefore, the present study concerns with Sikait-Nugrus area as one of the most prolific sites in this region. The study provides a detailed geological, structural, and mineralogical investigation of the monzogranites to describe and characterize the various alteration types and sequence. For this purpose, remote sensing, geochemical and petrographical techniques were applied. The remote sensing technique helped in constructing a detailed geologic map of the study area to follow up strictly the alteration zone of the Sikait-Nugrus area. Petrographically, the granites predominates in the study area, they are described as slightly and highly altered monzogranites. The slightly altered one is composed mainly of quartz (~ 20–35%), alkali feldspar (~ 25–30%), plagioclase (~ 25–30%), and mica (~ 5–15%), while accessory minerals are represented by zircon and monazite. On the other hand, the portion of this granite close to the shearing zone is intensively altered and characterized by sericitization as the main alteration processes. This sheared portion is characterized by accessory minerals as, uranothorite, allanite, fluorite and Nb-minerals (ishikawaite). Minerlogically, the altered monzogranites are predominated by the following mineral groups: (1) radioactive minerals as uranyl silicates (soddyite, uranophane and kasolite), and thorium minerals (thorite and uranothorite), (2) Nb–Ta minerals (betafite, plumbobetafite, columbite, fergusonite, and aeschynite), (3) REE minerals (monazite, cheralite and xenotime), and (4) zircon and fluorite as accessory minerals. Geochemically, the recorded pattern of the REEs tetrad effect (M-type) for the highly altered samples indicate that these granites are highly evolved and affected by late stage of hydrothermal alteration and the effective water-rich alteration processes that connected to intensive physico-chemical changes. The total REE concentrations equal 241.8 and 249.75 ppm for the highly and slightly altered samples. A significant mass change (MC) was analyzed by the isocon technique (22.95 & 11.11) and volume change (VC) (1.8 &-7.99) for the highly and slightly altered samples, respectively. The mass balance calculations and the isocon diagrams revealed that some major oxides were removed from the slightly altered monzogranites and transformed later into highly altered monzogranites with increasing the alteration intensity due to the impacts of hydrothermal alteration processes. The studied area is virgin, where no detailed studies have been applied to this region. It is extendable to other parts of the Arabian-Nubian Shield in around the Red Sea in Egypt, Sudan, Saudi Arabia and Yemen. The applied technical workflow is also extendible to other surface analogues everywhere. [ABSTRACT FROM AUTHOR]

While Eu2+ → Eu3+ energy transfer is well known, in this study the energy transfer from Eu3+ to Eu2+ is reported for the first time. The predominant condition for Eu3+ → Eu2+ energy transfer is a Eu2+ 4f55d band at lower energy than the position of the Eu3+ 4f6[5D0] level, which is fulfilled in Eu‐doped CaO. X‐ray powder diffraction, Eu Mössbauer spectroscopy and optical absorption measurements are employed to determine the Eu3+ and Eu2+ concentrations in the prepared CaO:1at.%Eu samples. Synthesis in an H2/N2 atmosphere and addition of graphite powder as a reducing agent to the starting mixture are found to result in respective Eu3+ and Eu2+ concentrations of 0.6–0.7% and 0.3–0.4%. For this sample, the Eu3+ → Eu2+ energy transfer efficiency is estimated to be high (> 90%). This is explained by the high oscillator strength of the 4f7 → 4f65d excitation transition of the Eu2+ ion to which energy is transferred. As the Eu2+ 4f55d band lies below the Eu3+ 4f6[5D0] level, Eu3+ does not act as a killer center for the near‐infrared (NIR) Eu2+ emission at about 720 nm. Therefore, a full reduction of Eu3+ is not required to attain a high quantum efficiency. Implications of the demonstrated Eu3+ → Eu2+ energy transfer for application of long wavelength Eu2+ phosphors are discussed. [ABSTRACT FROM AUTHOR]

ABSTRACT Five new lanthanide complexes {[Sm(H2L)(H2O)4(Cl)]⋅H2O⋅Cl}n (1), {[Eu(H2L)(H2O)4Cl]⋅Cl}n (2), {[La(H2L)(H2O)4Cl]⋅Cl}n (3), {[Pr(H2L)(H2O)4Cl]⋅Cl}n (4), {[Ce(H2L)(H2O)4Cl]⋅Cl}n (5) (H3L = 2‐hydroxy‐5‐(5‐(hydroxy‐λ2‐methoxy)‐1H‐benzo[d]imidazole‐5‐carboxylic acid) were successfully synthesized under solvothermal method. 1 exhibits a two‐dimensional (2D) network structure, whereas 2–5 feature one‐dimensional (1D) chain structure. The fluorescence investigations demonstrated that 1–5 could be the fluorescent sensor for nitrobenzene (NB) and Fe(III) ions with high selectivity, sensitivity, and low detection limits. Furthermore, 1–5 displayed the good adsorption to anionic dye Congo red (CR), and the adsorption capacities were 140.5, 206.5, 212.5, 111.5, and 211.5 mg·g−1, respectively. [ABSTRACT FROM AUTHOR]

In alkali metal‐doped optical temperature measurement materials, the influence of the electronegativity difference of alkali metal ions on optical temperature measurement performance is rarely reported. This study investigates and analyzes the performance of optical temperature measurement of Na0.5Gd0.5TiO3: Yb, Er doped with Li+ and K+ ions, utilizing the Judd‐Ofelt theory and the first‐principles method. The results reveal that the sensitivities increase with the increase of atomic number of doped alkali metal ions. The reason is that a difference in ionic radius between the dopant and the replaced ion decreases the symmetry of the crystal field and increases the value of Ω2. The doping K+ with low electronegativity leads to an increase in the s orbital electron density of rare earth ions, thereby repelling the d orbital electrons, reducing the d electron density, and decreasing the value of Ω6. Based on the Judd‐Ofelt theory, a combination of a large Ω2 and a small Ω6 is expected to enhance the absolute sensitivity of optical temperature‐measuring materials doped with rare earth ions. Therefore, it can be concluded that doping an ion with low electronegativity and a significant radius difference from the substitution site is beneficial for enhancing the optical temperature sensitivity. [ABSTRACT FROM AUTHOR]

Rare earth (RE)‐based perovskites are considered as promising platform for oxygen evolution reaction (OER) due to their low cost and tunable structures. However, the systematic synthesis of perovskite catalysts with satisfactory performance has rarely been reported. Herein, a general synthetic protocol for RE‐substituted LaCoO3 (RE‐LCO) perovskites is demonstrated. Particularly, after loaded with RuO2, the as‐prepared RuO2:0.2Ce‐LCO hybrid structures exhibit OER performance with a low overpotential of 135 mV at 10 mA cm−2 in 1.0 m KOH, together with remarkable long‐term operation, representing one of the most efficient and robust Ru‐based catalysts. Comprehensive experimental results indicate that the enhanced OER mechanism is attributed to the Ce‐substitution, which alters the geometric configuration of CoO6 octahedra and generates more oxygen vacancies. Furthermore, the robust interaction between Ce‐LCO and RuO2 stabilizes the valence state of Ru site. Theoretical calculations corroborate that Co 3d orbitals overlap with Ce 4f orbitals near the Fermi level, greatly improving the electron transfer between Co and Ce atoms. [ABSTRACT FROM AUTHOR]

Borosilicate glasses are the primary waste forms for the industrial immobilization of high‐level liquid waste. Yet, the compositional variation of waste glasses can form the diopside phase, which can be detrimental to the melting process and the properties of the final glass products. This study prepared simulated waste glasses with variable contents of alkaline earth metals, boron, transition metals, and rare earth metal oxide and subjected them to heat treatments. The effect of the compositional variation on the diopside crystallization behavior was explored using differential scanning calorimetry, X‐ray diffraction, optical microscopy, and scanning electron microscopy‐energy dispersive spectroscopy. The results revealed that the average size of diopside crystals was proportional to the square root of the heat treatment durations. Increased contents of alkaline earth and transition metal oxides could contribute to the growth of diopside crystals, while boron oxide tended to inhibit it. Finally, a prediction model correlating the average crystal size, compositional variation, and heat treatment durations was discussed. [ABSTRACT FROM AUTHOR]

Research on the recovery of rare earth elements from wastewater has attracted increasing attention. Compared with other methods, biosorption is a simple, efficient, and environmentally friendly method for rare earth wastewater treatment, which has greater prospects for development. The objective of this study was to investigate the biosorption behavior and mechanism of Yarrowia lipolytica for five rare earth ions (La3⁺, Nd3⁺, Er3⁺, Y3⁺, and Sm3⁺) with a particular focus on biosorption behavior, biosorption kinetics, and biosorption isotherm. It was demonstrated that the biosorption capacity of Y. lipolytica at optimal conditions was 76.80 mg/g. It was discovered that the biosorption process complied with the pseudo-second-order kinetic model and the Langmuir biosorption isotherm, indicating that Y. lipolytica employed a monolayer chemical biosorption process to biosorb rare earth ions. Characterization analysis demonstrated that the primary functional groups involved in rare earth ion biosorption were amino, carboxyl, and hydroxyl groups. The cooperative biosorption of rare earth ions by Y. lipolytica was facilitated by means of surface complexation, ion exchange, and electrostatic interactions. These findings suggest that Y. lipolytica has the potential to be an effective biosorbent for the removal of rare earth elements from wastewater. [ABSTRACT FROM AUTHOR]

Dense Sm 2- x Ce x O 3+ x /2 (x = 0.10−0.25) ceramics were obtained by the solid-state method. Main-phase Sm 2 O 3 with monoclinic structure and a small amount of fluorite-structured CeO 2 were achieved. As the x value increased, the τ f significantly reduced from 18.8 ± 2.0 ppm/°C to −20.3 ± 2.0 ppm/°C and the Q × f enhanced from 21,382 ± 300–32,927 ± 300 GHz. The τ f variating from positive to negative was related to the increasing temperature coefficient of ion polarizability (τ αm) from 20.6 ppm/°C to 27.9 ppm/°C. The rise in Q × f was attributed to the reduced AC conductivity resulting from the decreasing oxygen vacancy concentration. The addition of Ce could effectively inhibit the decomposition of Sm 2 O 3 ceramics in atmospheric condition. Notably, the Sm 1.80 Ce 0.20 O 3.10 ceramic sintered at 1475 °C demonstrated optimal microwave dielectric properties of ε r = 19.2 ± 0.2, Q × f = 28,033 ± 300 GHz, and τ f = 1.8 ± 2.0 ppm/°C. [ABSTRACT FROM AUTHOR]

Triassic granitoids are widespread in the East Kunlun Orogen (EKO), with Middle Triassic granitoids being dominant and Late Triassic granitoids being subordinate. This paper presents new whole-rock geochemical and Sr – Nd isotope, and zircon U – Pb age and Lu – Hf isotope data for eight granitoids in the Lalingzaohuo area, western EKO, northern Tibetan Plateau. These granitoids yield Middle and Late Triassic ages of 245–239 and 223–220 Ma, respectively. The granitoids from the Lalingzaohuo area have features typical of I-type granites and belong to the high-K calc-alkaline series. They exhibit variable rare earth and trace element patterns, and Sr – Nd – Hf isotopic compositions, indicative of different petrogenetic processes. The Middle Triassic samples have higher ISr values of 0.71440–0.71572 and lower εNd(t) values of −6.18 to −4.26 than the Late Triassic samples (ISr = 0.71139–0.71348; εNd(t) = –3.23 to −1.51), which are consistent with I-type granitoids derived from the lower crust. Geochemical and isotopic data indicate that the two stages of I-type granitoids had a significant mantle contribution. The Middle Triassic granitoids in the EKO, particularly the western EKO, have adakitic characteristics and formed by partial melting of lower continental crust. The T2–T3 granites formed by oceanic slab breakoff related to subduction and mantle convection, and the Late Triassic granites formed by lithospheric thinning and asthenospheric upwelling after slab breakoff. [ABSTRACT FROM AUTHOR]

Lu 2 O 2 S has high density, high melting temperature, and favorable thermal stability, making it an excellent matrix material for rare earth luminescence and X-ray sensitization screens. However, achieving high quality fluorescent powders with high crystal quality on a large scale is still challenging. By employing an optimized solid phase approach, Lu 2 O 2 S:Tb3+/Sm3+phosphors with a hexagonal shape and uniform particle size and showing high crystallization have been successfully synthesized. Spectral analysis reveals energy interaction between Sm3+ and Tb3+ in the Lu 2 O 2 S system (multistage interaction), indicated by spectral overlap, relative changes in luminescence intensity, and lifetime decay. By changing the excitation wavelength and dopant concentration, multicolor phosphors such as yellow-–green, orange–red, and orange–yellow could be created. Temperature-dependent emission spectroscopy shows that the system shows good luminescence performance even at high temperatures. X-ray excitation spectroscopy further confirm that the phosphors emit different colors (yellow, green and red) depending on the doping concentrations of Tb3+ and Sm3+ ion, indicating that the system has wide application potential in color displays and other relevant fields. [ABSTRACT FROM AUTHOR]

Liquid-phase sintering anorthite (LSA) glass-ceramics with degradation in citric-acid solution have been prepared from CaO–Al 2 O 3 –SiO 2 –B 2 O 3 low-melting compositions. By means of the chemical corrosion of the glass phases, LSA glass-ceramics are effectively degraded in the citric acid solution. Then, the influence of B 2 O 3 and rare-earth (RE) on the structures of glass phases, the degradation of LSA glass-ceramics in the citric-acid solutions, and the dielectric properties are investigated systematically. The results suggest that when the B 2 O 3 molar ratio in the composition CaO–Al 2 O 3 –SiO 2 –B 2 O 3 is 0.5, doping LSA glass-ceramics with RE can reduce the quantity of bridging oxygen and [BO 4 ] units in the glass phase, as well as the degree of network connection of [AlO 4 ] units in the glass network. Conversely, when the B 2 O 3 molar ratio is decreased down to 0.3, doping RE into LSA glass-ceramics increases the quantity of bridging oxygen and [BO 4 ] units for glass phase. This improvement in chemical stability effectively impedes the degradation of LSA glass-ceramics in citric-acid solutions. Concurrently, the degradation mechanism of LSA glass-ceramics in citric acid solution is analyzed and explained in terms of classical glass corrosion theory, while the microstructural characteristics of LSA glass-ceramics are utilized to investigate their dielectric properties. It indicates that the dielectric loss and dielectric constant of LSA glass-ceramics are significantly lowered as a result of the existence of the glass phase. Especially when the B 2 O 3 molar ratio in the composition CaO–Al 2 O 3 –SiO 2 –B 2 O 3 is 0.3, and the La 2 O 3 doping percentage into LSA glass-ceramics is 0.5 wt%, the LSA glass-ceramics exhibit the lowest dielectric loss value of 3.13 × 10−3 and ε r = 4.17. Developing the LSA glass-ceramic with degradation in organic acids can provide a new idea for the recycling and disposal of e-waste. [ABSTRACT FROM AUTHOR]

The rechargeable battery market has almost doubled in 15 years. Regardless of the type of batteries, their limited lifespan means that sooner or later they will constitute a mass of waste whose management is problematic as their content is high in elements and metals of high economic interest, but also toxic to the environment. This project is to optimize the solubilization conditions for rare earth elements (REEs) and other metals from waste nickel-metal hydride (Ni-MH) batteries. The Ni-MH battery powder used contained the following main elements: Ni (548 g/kg), La (45 g/kg), Co (32 g/kg), Zn (22 g/kg), Nd (15 g/kg), Sm (12 g/kg), and Ce (11 g/kg). The metals were solubilized in the presence of sulfuric acid. Acid concentration, solids concentration, leaching time, and temperature were optimized using the Box–Behnken design methodology. The optimal conditions identified are an H2SO4 concentration of 2 M, a S:L ratio of 10% (w:v), a leaching temperature of 60°C and a reaction time of 90 min. These conditions make it possible to solubilize 81% Ni, 99% Co, and 70% REEs, while the mathematical model predicted 83% Ni, 100% Co, and 80% REEs respectively. The process was also operated in counter-current leaching mode with the optimal parameters. The high solubilized yields obtained after five loops for all metals, REE and the significant reduction of water consumption confirm that this process leaching can be apply for industrial application. [ABSTRACT FROM AUTHOR]

Tungsten-bronze-type material Ba6-3xRE8+2xTi18O54, (RE = rare earth elements) is an important microwave dielectric that has shown great promises for future miniaturization of microwave devices because of its high dielectric constant, low loss, and tunabilities, and there is still much room for improvement. With their proven predictive power, first-principles calculations may greatly help accelerate materials optimization by reducing or eliminating the expensive and time-consuming experimental trial-and-error process. However, microwave dielectrics such as the tungsten-bronze-type materials are rather complex systems with unit cells containing hundreds or thousands of atoms, making ab initio calculations prohibitively expensive. In this work, we propose an elemental-unit decomposition (EUD) technique that can drastically reduce the computational effort of predicting the properties of complex microwave dielectrics and demonstrate its accuracy and efficiency. Our approach facilitates first-principles prediction and design of complex microwave dielectric materials that would otherwise be extremely difficult. [ABSTRACT FROM AUTHOR]

This study involved depositing thin films of copper oxide (CuO) and copper oxide films incorporated with neodymium oxide (Nd2O3) in various weight ratios using the pulsed laser deposition technique to fabricate an ammonia gas sensor. The characteristics of the developed films were characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and photoluminescence spectroscopy (PL) techniques. The study investigated the impact of incorporating Nd2O3 into the CuO film on its sensing characteristics. The X-ray analysis revealed a polycrystalline structure of CuO with a crystal size of 19 nanometers. Furthermore, incorporating CuO and Nd2O3 formed a mixed phase comprised of both CuO and Nd2O3. The average crystallite size varied with the Nd2O3 incorporation rate from 19nm to 14.7nm. With increasing Nd2O3 incorporation ratios, the surface morphology changed from smooth to spherical-like nanostructures, and the average particle sizes varied from 28nm to 130nm. The PL spectrum analysis results confirmed that the incorporation of Nd2O3 resulted in a change in the peak intensity of the PL spectrum, with a significant increase in the peak associated with oxygen vacancies, contributing to the improvement of the sensor response. The incorporation of Nd2O3 greatly enhanced the sensitivity of the as-deposited CuO film. The sample with 5 wt.% Nd2O3 exhibited the maximum sensitivity, reaching 180% against 79 ppm NH3 at a working temperature of 50∘C. [ABSTRACT FROM AUTHOR]

Maintaining a high specific energy without losing cycling stability is the focus of the supercapacitor field. In this study, carbon nanofibers including europium oxide nanoparticles (CNF/Eu2O3) have been synthesized in the presence of thiourea via a simple approach and applied for the first time as an electrode for SCs. The CNF/Eu2O3-1 electrode doped with nitrogen and sulfur heteroatoms possessed a favorable specific capacitance of 183.2 F g−1, a specific energy of 9.15 W h kg−1, and an excellent capacitance retention of 94.8% even after 10 000 cycles at 1 A g−1. Such excellent performance is ascribed to the surface functionalities, high surface area, and good interaction of Eu2O3 with CNFs. This strategy will provide guidance for other rare element-based electrodes in the field of energy storage. [ABSTRACT FROM AUTHOR]

Following recent investigation in the ternary system Sr–Al–Pt led to the discovery of SrAl5Pt3 which crystallizes in the orthorhombic YNi5Si3 type (Pnma) structure. Interestingly, only two more aluminum representatives, CeAl5Pt3 and EuAl5Pt3, have been reported to adopt this structure type. Therefore, we decided to investigate the existence range of compounds adopting the YNi5Si3 type structure. Besides the already known Sr, Ce and Eu members, the series could be extended to Ca, Y and La–Nd as well as Sm–Er. All compounds were synthesized from the elements and characterized by powder X-ray diffraction. While for CaAl5Pt3 and LaAl5Pt3 also the respective M2Al16Pt9 members were observed, the other compounds could be obtained either as X-ray pure materials or with small amounts of Al3Pt2 as a side phase. The structure of ErAl5Pt3 could be refined from single crystal data, verifying that also the small rare-earth elements adopt the YNi5Si3 type structure. Selected members of the series were furthermore characterized by magnetization and susceptibility measurements. Since YAl5Pt3 could be obtained as a phase pure material and exhibits no paramagnetic behaviour it was investigated by 27Al MAS NMR investigations. Also, XPS measurements were conducted on this compound to gain an insight into the charge distribution. Finally, quantum-chemical calculations supported the NMR measurements and gave an insight into the chemical bonding and the charge distribution. [ABSTRACT FROM AUTHOR]

Simple Summary: Rare earth elements (REEs) are widely used in various fields of human activity. However, data from many studies indicate the harmful effects of REEs on humans and animals, including the nervous system. In this study, we estimated the REE content in hair samples of children living on the Kola Peninsula (Murmansk region) in the vicinity of the Lovozersky REE Mining and Processing Plant, and we linked the REE content in children's bodies to the prevalence of the nervous system diseases in Lovozersky District. We observed a higher prevalence of nervous system diseases (episodic paroxysmal disorders (G40–G47), cerebral palsy (G80–G83), epilepsy and status epilepticus (G40–G41)) in children aged 15–17 years in Lovozersky District compared to other territories of the Murmansk region. Indirect evidence of the link between REE content in hair samples of children and nervous system diseases is provided by data in the literature. According to these data, REEs are deposited in the brain structures responsible for the function of the nervous system, thus impairing them. This investigation highlights the relevance of studying the role of REEs in nervous system diseases, and it points to the need for the further research in this area. The aim of this study is to assess the rare earth element (REE) content in hair samples of children living in Lovozero village, near an REE mining site, and the possible effects of REEs on the prevalence of nervous system diseases in Lovozersky District (Murmansk region, Kola Peninsula). Fifty-three school-age children were recruited for the analysis of REE content in hair samples. REE (Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu) content was estimated by means of inductively coupled plasma mass spectrometry (ICP-MS). The analysis of REE content in the hair of children living in Russia, Kazakhstan, and China indicated REE intake from the environment. The possible contribution of REEs to nervous system disorders is supported by the link between the REE content in hair samples of children living near REE mining areas (China) and the manifestation of cognitive disorders in these children. It is also found that the prevalence of nervous system diseases in children aged 15–17 years is higher in Lovozersky District compared to the other districts of the Murmansk region. In this paper, the possible contribution of REEs to the prevalence of episodic paroxysmal disorders (G40–G47), cerebral palsy (G80–G83), and epilepsy and status epilepticus (G40–G41) is discussed. [ABSTRACT FROM AUTHOR]

Garnets are observed as phenocrysts in blocky rhyolites of Cumaovası Volcanites and are reddish-blackish in color, show vitreous luster, and have dodecahedron forms varying between 0.5 and 2.0 cm in size. In optical microscope investigations, they exhibit fractured structures and contain quartz, hematite, chlorite, and acicular rutile inclusions. Garnet phenocrysts are highly consistent with spessartine-type garnet end members in the Raman spectrum. This result is supported by the mineral chemistry results determined as spessartine (Sps)0.50–0.52 almandine (Alm)0.47–0.48 grossular (Grs)0.01–0.02. In the chondrite, primitive mantle, and Mid-Oceanic Ridge Basalt normalized multi element variation diagrams, garnet phenocrysts show enrichment in all elements (except Sr, K, P, and Ti). In contrast, in the upper continental crust normalized multi element variation diagram, garnet phenocrysts show depletion in large ion lithophile elements (Rb, Ba, K, and Sr) relative to high field strength elements. They exhibit slight enrichment in light rare earth elements ((La/Sm)N = 0.11–1.07) relative to heavy rare earth elements ((Sm/Yb)N=0.78–0.97). Furthermore, garnet phenocrysts have significant negative europium (Eu) ((Eu/Eu*)N = 0.01–0.02) and mildly positive cerium ((Ce/Ce*)N = 2.43–13.77) anomalies indicating hot and reduced magma conditions. The Y/Ho ratios have ranged from 18.9 to 20.3 and are close to the chondrite value. The zircon saturation temperatures (TZr) of the garnet's host rock was determined to be 756 °C. As a result of mineralogical, geochemical and gemological studies, it was concluded that Görece garnet phenocrysts have glassy luster and semi-transparent dodecahedral crystal shapes, so they can be classified as semi-precious gemstones. In addition, the rare earth element content of the garnet phenocrysts is similar to that of industrial garnet sands and it is thought that they may have potential. [ABSTRACT FROM AUTHOR]

Triethylamine is a common volatile organic compound (VOC) that plays an important role in areas such as organic solvents, chemical industries, dyestuffs, and leather treatments. However, exposure to triethylamine atmosphere can pose a serious threat to human health. In this study, gas-sensing semiconductor materials of LaFeO3 nano materials with different Mo-doping ratios were synthesized by the sol–gel method. The crystal structures, micro morphologies, and surface states of the prepared samples were characterized by XRD, SEM, and XPS, respectively. The gas-sensing tests showed that the Mo doping enhanced the gas-sensing performance of LaFeO3. Especially, the 4% Mo-doped LaFeO3 exhibited the highest response towards triethylamine (TEA) gas, a value approximately 11 times greater than that of pure LaFeO3. Meantime, the 4% Mo-doped LaFeO3 sensor showed a remarkably robust linear correlation between the response and the concentration (R2 = 0.99736). In addition, the selectivity, stability, response/recovery time, and moisture-proof properties were evaluated. Finally, the gas-sensing mechanism is discussed. This study provides an idea for exploring a new type of efficient and low-cost metal-doped LaFeO3 sensor to monitor the concentration of triethylamine gas for the purpose of safeguarding human health and safety. [ABSTRACT FROM AUTHOR]

Summary: This study investigated the variation in mineral elements in bracatinga (Mimosa scabrella Bentham) honeydew honeys produced biannually over three consecutive harvest years. The aim was to assess the relationship between the year of production and the concentration of fourteen rare earth elements and six trace elements analysed using ICP‐MS. The concentrations of the twenty elements varied (P < 0.001) among all the honey samples. The dominant rare earth elements were Eu, followed by Nd and La, while Pd and Au were the major trace elements. Cluster analysis (CA) and linear discriminant analysis (LDA) were performed using all the elements identified. The LDA categorised (83.3% accuracy) the bracatinga honeydew honey samples according to their harvest year. Discriminant functions, influenced by Ce, Tb, and Th, show distinct elemental patterns in bracatinga honeydew honeys, varying with harvest year. This reflects fluctuations in yearly climatic conditions and is important to guarantee accurate characterisation. [ABSTRACT FROM AUTHOR]

Rare‐earth tantalates present promise as thermal barrier coatings due to their favorable thermodynamic characteristics. To further diminish thermal conductivity, three high‐entropy tantalate samples, namely (Ce0.2Nd0.2Sm0.2Eu0.2Lu0.2)3TaO7, (Nd0.2Sm0.2Eu0.2Gd0.2Tm0.2)3TaO7, and (Ce0.2Nd0.2Sm0.2Eu0.2Dy0.2)3TaO7, denoted as HE‐1, HE‐2, and HE‐3, respectively, were synthesized in this investigation. HE‐1 exhibits a low thermal conductivity of 1.46 W/(m·K)–1 at 1000°C. The rationale behind this reduced thermal conductivity is expounded via the phonon scattering mechanism. The introduction of atomic disparities and grain size inhomogeneity, attributable to high‐entropy doping, collaborates to enhance phonon scattering, culminating in the lowest thermal conductivity. HE‐3, on the other hand, possesses a notable thermal expansion coefficient of 11.6 × 10−6 K−1 at 1200°C and manifests pronounced anisotropy in CTEs. All three high‐entropy samples demonstrate commendable mechanical properties, with Young's modulus lower than that of single‐component rare‐earth tantalates, while simultaneously exhibiting high hardness values (>8.4 GPa). This work furnishes a valuable reference for the utilization of high entropy rare‐earth tantalates in the realm of thermal barrier coatings. [ABSTRACT FROM AUTHOR]

Distinctive luminescent properties and excellent stability of long persistent luminescent (LPL) glass‐ceramic hold promise for anti‐counterfeiting and encryption applications. However, rational synthesis and a deep understanding of the precipitation of dual‐phase microcrystals in glass substrate to improve the encryption level remain challenging. Here, we carefully designed the components based on the phase diagram and combined them with the glass‐forming region. By utilizing the different crystallization behaviors of SrAl2O4 and CaAl2O4 in the glass matrix to realize dual crystals coexistence in a borate glass matrix, which provides different crystal field environments for Eu2+ luminescence, thus obtaining excitation‐dependent tunable LPL characteristics in a single sample. Mechanism studies unveiled that this excitation‐dependent behavior arises from the differential capture of charge carriers by defect oxygen vacancies in the sample when charged with different laser sources, providing a channel for multimode anti‐counterfeiting encryption. This strategy of constructing a double crystal field in a glass matrix overcomes the stringent requirements of a single heat treatment method for the crystallization temperature of biphasic crystals, which could become a stable and promising advanced anti‐counterfeiting encryption material and provide new insights into the multi‐band luminescence regulation of rare earth ions. [ABSTRACT FROM AUTHOR]

Rare earth silicates are promising environmental/thermal barrier coating (E/TBC) materials facing severe CMAS (CaO‐MgO‐Al2O3‐SiO2) corrosion. Previous studies mainly focused on the intrinsic properties of precorrosion coatings, but there were few studies on their CMAS corrosion products that play a crucial role in the performance of coatings in postservice stage. In this work, the mechanical and thermal properties of nine corrosion products between lutetium silicates and CMAS are studied using first‐principles calculations. Their differences of elastic stiffness are attributed to the different crystal structures and bonding strength. The T:O ratio is identified as a factor of the crystal structure for silicate products, and it has a good correlation with their elastic stiffness. Moreover, the divergences of thermal conductivity are dominated by three essential factors, that is, atomic vibration intensity, lattice vibrational anharmonicity, and complexity of crystal structure. Compared with rare earth silicates, six products, that is, the α‐CaSiO3, β‐CaSiO3, Ca2MgSi2O7, Ca2Al2SiO7, CaAl2Si2O8, and Ca2Lu8(SiO4)6O2, showing good damage tolerance and low thermal conductivities, are predicted to be advantageous to E/TBCs. These discoveries reveal the mechanical/thermal properties of corrosion products between lutetium silicates and CMAS and are expected to support the future researches on the performance of E/TBC in the postservice stage. [ABSTRACT FROM AUTHOR]