Effects Of Rare Earth Elements Research Articles

Effect of rare earth element on amorphization and deformation behavior of crystalline/amorphous dual-phase Mg alloys

The crystalline/amorphous (C/A) dual-phase structure is a new design strategy to improve the mechanical properties of Mg alloys. Here, the effect of the content of rare-earth element Y on the deformation mechanism and mechanical behavior of the C/A Mg/(MgCu)100-xYx dual-phase Mg alloys under tensile loading is investigated by molecular dynamics simulation. The results show for the first time that the amorphous phase thickness of the alloys increases obviously after relaxation, which is mainly due to the existence of element Y in amorphous phase. And with the increase of the content of element Y, the thickness of amorphous phase increases. The results indicate that the diffusion of element Y from amorphous phase to amorphous-crystalline interface (ACI) promotes the migration of ACI towards crystalline phase (i.e., the amorphization of crystalline phase). The results further pointed out that the amorphization of Mg alloys depends on two factors: one is that the amorphous phase contains a certain concentration of element Y, and the other is the existence of ACI. The results show that there is a critical amorphous phase thickness of the dual-phase Mg alloys, that is, the critical content of Y element, which can make it achieve nearly perfect plasticity.

Effect of rare earth elements on magnetic properties of non-oriented electrical steels

The effect of rare earth elements (REMs) on the magnetic properties of non-oriented electrical steels was studied using industrial trials. The variation of the magnetic properties was discussed in terms of the effect of inclusions, precipitates, grain size, and textures in the steel with and without REMs. Inclusions of MgO·Al2O3-CaS and (Mg, Mn, Ca)S in REMs-free steel were modified into composite ones of MgO·Al2O3-LaAlO3, La2O2S-MgO and (La, Ca)S in the steel with 0.0006% lanthanum, and to (La, Ce)2O2S-CaS-MgO, (Ce, La)S in the steel with 0.0007% lanthanum and 0.0015% cerium. The number density of fine MnS was remarkably decreased by the addition of REMs, leading to an increase in the average grain size. The steel containing 0.0006 wt% lanthanum possessed the best combination of core loss and magnetic induction due to the decrease of micro-sized inclusions and fine MnS, the increase of grain size, and the optimization of recrystallization textures. For the steel with excess REMs addition, the large number density of rare earth sulfides with the size of approximately 1 μm tended to deteriorate the grain size and textures.

Enhanced mechanical properties of as-cast rare earth bearing magnesium alloy via elevated-temperature homogenization

The effects of elevated-temperature homogenization on the microstructure and mechanical properties of a magnesium alloy containing mischmetal rare earth (RE) were investigated. It was revealed that the homogenization treatment leads to spheroidization and partial dissolution of the Mg12RE phase in the eutectic constituent. For the optimum homogenized alloy (20 h at 535 ºC), the elimination of the deleterious eutectics and the solid solution strengthening effect of RE elements were the main contributing factors for improving the ultimate tensile strength and ductility. Accordingly, a 157 % increase in tensile toughness compared to the as-cast condition was recorded. Moreover, as a direct consequence of eliminating the eutectic constituent, homogenization led to a change in the fracture mechanism from a brittle intergranular mode to an intragranular cleavage with the incorporation of some ductile dimples. Accordingly, homogenization heat treatment was found to be an alternative enhancing route of strength-ductility trade off, besides thermomechanical processing (by hot deformation and dynamic recrystallization) and severe plastic deformation.

The effect of rare earth element doping on thermoelectric properties of GeTe

GeTe has attracted extensive attention due to high thermoelectric performance. Herein, we comprehensively investigate the effect of rare earth element (Eu, Gd, Er and Tm) substitutions at Ge site of GeTe on its thermoelectric performance. It is found that the substitution limit of Eu, Gd, Er and Tm at Ge site of GeTe increases from 0.8 to 1.8 mol.% with increasing atomic number. The local magnetic moment arising from the substituted rare earth element enhances the Seebeck coefficient and in turn results in enhanced power factor at the entire measurement temperature range (from 303 to 723 K). Additionally, the increasing substitution limit with increasing atomic number of rare earth element strengthens the mass and strain-field fluctuations, which contributes to strengthened phonon scattering, and leads to reduced lattice thermal conductivity. The simultaneously enhanced power factor and reduced lattice thermal conductivity enhances the dimensionless figure of merit at the entire measurement temperature range, and correspondingly enhances the average dimensionless figure of merit from 0.38 of GeTe to 0.63 of Ge0.98Er0.02Te. This work indicates rare earth element can be used an effective dopant in GeTe to improve the thermoelectric properties.

Synergistic effects of solutes on active deformation modes, grain boundary segregation and texture evolution in Mg-Gd-Zn alloys

Synergistic effects of rare earth elements (RE) and Zn have a major impact on the properties of ternary Mg-RE-Zn alloys. This study illuminates their dependence on the solute ratio by comparing texture evolution, solute segregation, and active deformation modes of three Mg-Gd-Zn alloys with a varying Gd:Zn ratio of 2:1, 1:1 and 1:2. A low Gd:Zn ratio led to a texture featuring a pronounced TD-tilted basal pole spread alongside a magnified solute segregation at grain boundaries, indicating a significant impact of solute-boundary interactions on RE-texture formation. Atom probe tomography revealed major alterations of the segregation energy of both Gd and Zn, depending mainly on the solute ratio rather than the absolute solute concentration. Additionally, the alloy with the smallest Gd:Zn ratio, i.e. Gd:Zn = 1:2, showed the highest direction dependent anisotropy of the yield stress under tensile strain, which was attributed to a magnified anisotropy of twinning depending on the Gd:Zn ratio. EBSD assisted slip trace analysis showed that the occurrence of non-basal slip systems could be increased by reducing the Gd:Zn ratio. Synergistic solute effects were found to be crucial for the activation of non-basal slip, solute segregation, as well as the formation of RE-texture components and proven to be highly sensitive to the solute ratio.

Effect of rare earth elements on the segregation behavior and microstructure of super austenitic stainless steel

Super austenitic stainless steel (SASS) was prepared by non-consumable vacuum arc melting for the first time. The effects of rare earth (RE) elements on its solidification microstructure and segregation behavior were investigated. The σ phase is the main precipitation phase in SASS. The addition of RE elements can refine the solidification microstructure and the dendrite spacing. The addition of RE elements reduced the secondary dendrite spacing at top (S1) by 5.22 μm. The elements as Cr, Mn, and Mo have positive segregation, and elements as Ni and Fe have negative segregation. The addition of RE elements has the trend of reducing element segregation, thereby inhibiting the σ phase precipitation. And the addition of RE reduces the hardness of the secondary phase.

The effect of rare-earth element (Gd, Nd, La) doping of NiO films on UV photodetector

The semiconductor-based UV photodetectors are the most essential devices in the field of space observations, military, DNA sequencing, analysis of protein, medical imaging, checking of atmospheric pollution, optical communications radiation, etc. With such a wide range of possible applications, the nanostructured pristine and rare-earth (RE) doped NiO ((NiO: Gd(1%), NiO:Nd(1%), NiO:La(1%)) thin films were prepared and investigated for their suitability as UV photodetectors. The films were prepared by nebulized spray pyrolysis (NSP) at a substrate temperature of 450 °C. The x-ray diffraction studies confirm the cubic single phase with the polycrystalline nature of the prepared films. The spectroscopic studies such as absorbance and photoluminescence confirm that increase in the optical bandgap and 391 nm PL emission is attributed to the near band edge emission of the NiO. The x-ray photoelectron spectroscopy reveals the presence of nickel and the doped elements with their oxidation states. The UV photodetector performance of the prepared NiO films was carried out under the irradiation of 365 nm light. The NiO:Gd exhibits the best responsivity (0.353 AW−1), external quantum efficiency (120%), detectivity (1.72 × 1010 Jones) and rise time (2.0 s), and fall time (2.2 s). Importantly, strategies such as limited doping (1 at.%) and larger ionic radii of Gd incorporation into the host NiO cause a moderate increase in the lattice distortion and inhibit the recombination rate instead of behaving as a recombination center. In addition, the conduction band (CB) electrons are trapped by a greater number of oxygen vacancies residing at the Gd3+ 4f state and cause a good separation of charge carriers. Overall, these modifications enhance the mean lifetime of electrons, consequently reducing the recombination rate and enhancing the photoresponse.

Effect of Rare Earth Elements on the Microstructural and Mechanical Properties of ZK60 Alloy after T5 Treatment

Effect of Rare Earth Elements on the Microstructural and Mechanical Properties of ZK60 Alloy after T5 Treatment

Effects of rare earth elements (REE) on terrestrial organisms: current status and future directions.

Rare Earth Elements (REE) are becoming increasingly important economically and highly exploited, thus contributing to REE increases in ecosystems. The ecotoxicological effects of REE on the terrestrial environment are, however, not fully understood and information on the biological effects of REE is urgently required for environmental risk assessments. In this review, studies and gaps in the existing scientific literature regarding the toxicological effects of REE on terrestrial organisms are presented. A total of 41 articles from the Web of Science database are discussed. La and Ce are the most studied elements, while little information is found concerning heavy REE. Most studies have been performed on plant species and few investigations are available for animals. Plant effects such as reduced mitotic index, germination and photosynthesis and antioxidant system enzyme alterations have been reported. Invertebrate effects include mortality, reproduction alterations and reduced locomotion. Based on the limited number of articles on terrestrial environment REE effects, this review highlights the need for more detailed studies in order to elucidate the effects associated with the REE hormesis and perform complete risk assessments with the establishment of safe REE usage limits.

Selection of optimal models for predicting growth stress in Artemisia desertorum by comparison of linear regression and multiple neural networks: Take the construction of a green mine in the Bayan Obo mine as an example

In recent years, more and more countries are focusing on the control of mining sites and the surrounding ecological environment, and the new environmental concept of green mines has been proposed. By investigating the ecological background of a mine site, pollution and ecological imbalances in the mine can be predicted, managed or transformed. This study investigated the effects of rare earth elements on plant growth in the Baotou Bayan Obo Rare Earth Mine and evaluated soil contamination and subsequent remediation through the measured plant height. Using linear regression, BP(Back Propagation) neural networks, GA-BP(Genetic Algorithm- Back Propagation) neural networks, ELM(Extreme Learning Machine) and GA-ELM(Genetic Algorithm- Extreme Learning Machine) model prediction instruments, the different rare earth solution concentrations were set as input values and the heights of Artemisia desertorum, which as the model plant, were set as output values in the prediction. The results showed that the linear regression predicted the standard error of single La(III), Ce(III) solution and compound La(III) + Ce(III) solution for Artemisia desertorum growth stress was on the high side, 7.02%− 8.92%; the efficiency range of each group of models under BP neural network, GA-BP neural network and ELM neural network were 1.15%− 2.53%, 0.85%− 1.28%, 1.76%− 3.53%; while the efficiency range under GA-ELM neural network was 0.59%− 0.68%, with average error values and predicted values close to the true values. Among them, the MAPE of GA-ELM neural network are significantly lower than other models, and the error decreases with increasing concentration of the compound solution. So GA-ELM neural network can be used as an efficient, fast and reasonable optimal model for predicting the growth stress of Artemisia desertorum in Bayan Obo mining area. The experimental results can provide a theoretical basis for assessing the risk of soil rare earth contamination in the area, evaluating the expectation of later remediation, and provide a degree of new ideas for the construction of green mines.

Effect of rare earth element Y(III) on short‐term denitrification performance of anaerobic ammonia oxidized granular sludge

AbstractBACKGROUNDThe ammonia‐nitrogen wastewater generated during rare‐earth mining poses a serious hazard to the environment around the mine. This type of wastewater is difficult to treat using conventional biological methods due to its low carbon‐to‐nitrogen ratio. Anaerobic ammonia oxidation (anammox) has become the first choice for treating rare earth mine wastewater. However, the effect of rare earth elements (REEs) in wastewater on anammox bacteria has been insufficiently studied, and this limits the application of this process. Yttrium is a rare earth element present in wastewater, and the study of its effect on anammox can help in the application of this process in rare earth mine wastewater.RESULTSThe effect of Y(III) on anammox granular sludge was studied using batch experiments. Anammox activity decreased with increasing Y(III) concentration, from 64.78 ± 0.28 to 17.15 ± 2.70 mg g−1 VSS day−1. The semi‐inhibitory concentration (IC50) of Y(III) for anammox activity was 30.36 mg L−1. Y (III) exhibited low promotion and high inhibition of anammox bacterial extracellular polymer secretion (EPS). Comparing the kinetic models, the Loung model is better suited for describing the kinetic equation of substrate concentration on anammox.CONCLUSIONThe acute toxicity of Y(III) to anaerobic sludge is influenced by the substrate and Y (III) concentrations. EPS‐based defence strategies play an important role in counteracting the toxicity of Y(III). The Edwards model fits the experimental data well and is suitable for predicting the inhibition of anammox activity by the substrate concentration. © 2022 Society of Chemical Industry (SCI).

Correction to Effects of Rare Earth Elements’ Physicochemical Properties on Their Stabilization during the Fe(II)aq-induced Phase Transformation of Ferrihydrite

Correction to Effects of Rare Earth Elements’ Physicochemical Properties on Their Stabilization during the Fe(II)_<i>aq</i>-induced Phase Transformation of Ferrihydrite

Effects of rare earth elements on bacteria in rhizosphere, root, phyllosphere and leaf of soil\u2013rice ecosystem

The effects of rare earth mining on rice biomass, rare earth element (REE) content and bacterial community structure was studied through pot experiment. The research shows that the REE content in rice roots, shoots and grains was significantly positive correlated with that in soil, and the dry weight of rice roots, shoots and grains was highly correlated with soil physical and chemical properties, nutrient elements and REE contents; The exploitation of rare earth minerals inhibited a-diversity of endophytic bacteria in rhizosphere, root, phyllosphere and leaf of rice, significantly reduced the abundance index, OTU number, Chao, Ace index and also significantly reduced the diversity index–Shannon index, and also reduced uniformity index: Pielou’s evenness index, which caused β-diversity of bacteria to be quite different. The exploitation of rare earth minerals reduces the diversity of bacteria, but forms dominant bacteria, such as Burkholderia, Bacillus, Buttiauxella, Acinetobacter, Bradyrhizobium, Candida koribacter, which can degrade the pollutants formed by exploitation of rare earth minerals, alleviate the compound pollution of rare earth and ammonia nitrogen, and also has the function of fixing nitrogen and resisting rare earth stress; The content of soil available phosphorus in no-mining area is lower, and the dominant bacteria of Pantoea formed in such soil, which has the function of improving soil phosphorus availability. Rare earth elements and physical and chemical properties of soil affect the community structure of bacteria in rhizosphere and phyllosphere of rice, promote the parallel movement of some bacteria in rhizosphere, root, phyllosphere and leaf of rice, promote the construction of community structure of bacteria in rhizosphere and phyllosphere of rice, give full play to the growth promoting function of Endophytes, and promote the growth of rice. The results showed that the exploitation of rare earth minerals has formed the dominant endophytic bacteria of rice and ensured the yield of rice in the mining area, however, the mining of mineral resources causes the compound pollution of rare earth and ammonia nitrogen, which makes REE content of rice in mining area significantly higher than that in non-mining area, and the excessive rare earth element may enter the human body through the food chain and affect human health, so the food security in the REE mining area deserves more attention.

Two dimensional nanosheets as immunoregulator improve HIV vaccine efficacy.

Two-dimensional (2D) nanosheets as carriers have shown promising potential for surface-displaying or loading various drugs. Nevertheless, developing sheet-like materials themselves into an immunoregulator has never been realized so far. In this study, we take advantage of the immunoregulatory effects of rare earth elements themselves and develop water-soluble erbium–dysprosium 2D nanosheets (2D NSs). Such 2D NSs can target lymph nodes and activate macrophages to improve vaccine efficacy in mice significantly. Transcriptome analysis further reveals that six critical molecules (Msr1, Ccr2, Serpinb9, Klrk1, Klrd1, Klrc1) closely correlate with 2D NS-mediated immunoregulation in vivo. For the first time, the present work realizes a proof-of-concept for designing immunoregulatory 2D NSs and shows a promising potential of 2D NSs for improving the immunoprophylaxis/immunotherapy of vaccines.

Effects of Rare-Earth Elements on the Microstructure and Electrochemical Properties of As-Cast La0.6r0.15mg0.25ni3.5 (R = La, Pr, Nd, Gd) Alloys with Multiphase Structure

Effects of Rare-Earth Elements on the Microstructure and Electrochemical Properties of As-Cast La0.6r0.15mg0.25ni3.5 (R = La, Pr, Nd, Gd) Alloys with Multiphase Structure

Effects of Rare-Earth Elements on the Microstructure and Electrochemical Properties of As-Cast La0.6r0.15mg0.25ni3.5 (R = La, Pr, Nd, Gd) Alloys with Multiphase Structure

Effects of Rare-Earth Elements on the Microstructure and Electrochemical Properties of As-Cast La0.6r0.15mg0.25ni3.5 (R = La, Pr, Nd, Gd) Alloys with Multiphase Structure

Investigation of Environmental and Biological Effects of Rare Earth Elements (REEs) with a Special Focus on Industrial and Mining Pollutions in Iran: A Review

The present article is a review study on the types of rare earth elements (REEs), environmental and biological effects as well as the sources of emission of these elements as pollution in nature. The purpose of this study is to provide a vision in environmental planning and control of pollution caused by REEs. The evaluation of rare earth elements was studied in human life and its environmental and biological effects, which have particular importance and are entering the life cycle through industrial and mining pollution sources. Since mining activities intensify the dispersion of these elements in the environment and the existence of industrial factories located around urban drainage system plays a unique role in creating and spreading pollution caused by rare earth elements; As a result, two case studies were conducted on two mining and industrial areas. The first case is the Choghart mine in Yazd province as an example of mining pollution,and the second case study is performed on the Kor river as an example of industrial pollution which is caused by industrial activities around it, Then the results are well explained to show both two environments of litho and hydro. Due to this fact that produced environmental pollution can cause exchange pollutant compounds with the surrounding environment besides its long-lasting destructive effects; It can cause irreversible biological effects on living organisms. By targeting this evaluation, several techniques can be proposed to prevent the entry and dispersal of rare earth elements from pollution sources besides methods to reduce the damage of these elements to the ecosystem.

Investigating the toxically homogenous effects of three lanthanides on zebrafish

The adverse effects of rare earth elements (REEs) have been increasingly reported in the past decades and have raised concern about their environmental toxicities. However, the available data is insufficient to elucidate the toxic effects, mechanisms, and whether the toxicity across all REEs is uniform. In this study, zebrafish were exposed to 0, 0.8, 1.6, 3.2, 6.4, 12.8 and 25.6 mg/L Ln(NO3)3•6H2O to test the acute toxicity of La(III), Ce(III), and Nd(III). LC50 of the three lanthanides was compared to the extent of the impact on gene expression. We carried out the functionally grouped network-based transcriptome analysis using gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) to explore the molecular mechanisms. The acute toxicity test showed that LC50 of La(III), Ce(III), and Nd(III) were 2.53, 2.03, and 2.76 mg/L, respectively. Consistent with acute toxicity, Ce(III) caused a little more DEGs than La(III) and Nd(III). Some biological processes such as metabolism of xenobiotics, oocyte meiosis, steroid biosynthesis, DNA replication, and p53 signaling pathway were affected following exposure of all the three lanthanides. Ce(III) also induced changes in the chemokine-mediated signaling pathway. The results indicated that the lethality is comparable, and the toxic patterns are similar across the three lanthanides. This study gives comparative research on the toxicities of three lanthanides to model organism zebrafish.

The Re2Sn2O7 (Re = Nd, Sm, Gd) on the enhancement of fire safety and physical performance of Polyolefin/IFR cable materials

Polyolefin (PO) cables used in confined spaces need to have low smoke, low heat release, low toxic gas release and excellent physical properties. In this work, a series of rare earth stannates Re2Sn2O7 (RES, Re = Nd, Sm, Gd) with high temperature catalytic performance were prepared by hydrothermal method for synergistic flame retardant PO/IFR. The flame retardancy, heat release, smoke density, toxic gas release and physical properties of PO composites were thoroughly studied in detail. The RES could enhance the vertical burning rating and the limiting oxygen index (LOI) of PO/IFR composites. Moreover, the residual char of the thermogravimetric analysis increased from 9.7% to 11.4 wt% after the RES added in PO/IFR system. Interestingly, the PO/IFR system containing Gd2Sn2O7 exhibits the lowest peak heat release rate of 233.7 kW/m2. Excellent flame resistance due to the formation of a complete and compact protective char layer. In addition, the toxic release of PO during combustion is also effectively reduced by introducing the RES. The tube furnace combustion test shows that the emission of carbon oxide (CO) and hydrogen cyanide (HCN) of PO/IFR/Gd2Sn2O7 are the lowest. It can be attributed to the catalytic effect of rare earth elements and the blocking effect of the dense char layer. In addition, compared with the PO/IFR composites, the PO/IFR/RES system demonstrate higher mechanical properties and volume resistivity. Therefore, the addition of RES has a positive effect on improving the physical properties and fire safety properties of the PO/IFR cable composites, especially suitable for using in confined spaces.

Effect of rare-earth elements on microstructure and mechanical properties of in-situ Fe-TiB2 composites

By integrating stiff and light TiB2 particles into an iron matrix, the Fe-TiB2 composite provides a viable approach for lightweight structural material design. The Fe-TiB2 composites are fabricated by melting and casting with TiB2 particles produced in-situ by a pseudo-binary eutectic reaction during solidification. However, this results in coarsening of TiB2 particles and thus degrades the mechanical properties of the fabricated composites. In this study, Sm, Y, Gd, Nd, Ce, and La were added to hypereutectic Fe-TiB2 composites (Fe–10.35% Ti–18 at% B). The effects of the addition of different rare-earth (RE) elements on the microstructure and mechanical properties of the composites were studied. Alloying the composites with Sm, Y, Gd, Nd resulted in the coarsening of TiB2 primary particles in Fe-TiB2 composites while lowering their number density; however, it also reduced the eutectic spacing and size of the α-Fe grains. This reduced the average interparticle spacing, leading to marginally increased tensile strength and hardness. Furthermore, the addition of Ce and La significantly refined the TiB2 primary particles and scattered them into a more dispersive distribution while the eutectic spacing and size of the α-Fe grains decreased. Alloying with La, in particular, primarily reduced the interparticle spacing, resulting in a significant strengthening of mechanical characteristics. The La-added specimen reached an ultimate tensile strength (UTS) of up to 778.2 MPa and a hardness of up to 3.96 GPa, respectively 15.1% and 32.9% higher than that of the non-RE specimen.