Rare Earth Sm Research Articles

Phytotoxicity of single and mixed rare earth element (La, Nd and Sm) exposures on Lactuca sativa seed germination and growth.

The mode of action, bioaccumulation potential and toxicity of Rare Earth Elements (REE), with several applications in the technology, medical and agricultural fields, are still understudied. The nitrates acute effects on single exposures, binary and ternary mixtures of lanthanum (La), neodymium (Nd) and samarium (Sm) on Lactuca sativa lettuce seed germination and wet biomass in an artificial soil (AS) and an Ultisol were assessed. Germination (EC50), wet biomass (IC50) and germination inhibition (% GI) were evaluated. EC50 values show La was the most toxic in Ultisol, Sm in AS, and Nd appears with intermediate values on both substrates. The IC50, both single and mixed, decreased from 3- to 181-fold with increasing test concentrations in relation to the control in AS, while increases in Ultisol were observed, followed by decreases at higher doses which may be associated with the low-dose stimulation effect (hormesis). Our findings may be used to subsidize REE risk assessment studies and reinforce the hormesis effect to prevent the use of high application of REE fertilizers, avoiding the accumulation of REE in agricultural soils.

Enhanced spin–orbit torque in Pt/Sm/Co/Ta heterostructures by interface alloying with light rare-earth Sm layer

Enhanced spin–orbit torque in Pt/Sm/Co/Ta heterostructures by interface alloying with light rare-earth Sm layer

Influence of non-stoichiometric design concepts on the optical properties of Sm-doped Gd2Zr2O7 transparent ceramics

The concept of non-stoichiometric design, as a historically significant strategy in material design, plays a crucial role in the development and innovation of materials. Particularly in the domain of red-orange fluorescence, the importance of the rare earth Sm element has been increasingly emphasized. This study successfully prepared non-stoichiometric Gd2Zr2O7 transparent ceramics doped with Sm using combustion and vacuum sintering. X-ray diffraction analysis indicates that the obtained powders are composed of fine defect fluorite structure grains, while the final ceramics exhibit pyrochlore/defect fluorite phase. Initially, non-stoichiometric design optimizes the optical transmittance of ceramics. The maximum transmittance of the X = −0.1 ceramic exhibits the highest transmittance 82.4 % @ 1134 nm. Furthermore, photoelectrons captured by native defects energy levels can transfer to the Sm excited states, optimizing the fluorescence property of ceramics. The fluorescence intensity of the X = 0.8 ceramic is about five times that of the X = 0 ceramic.

Crystal Structure, Optical, Photoluminescence, Raman, and Magnetic properties for Sm-doped Cr-Mg-Bi Ferrites using sensor

The current work,A series of rare earth Sm3+ ion substituted Cr-Mg-Bi ferrites Cr0.7Mg0.2Bi0.1SmxFe2-xO4 (x = 0.00, 0.02, 0.04, and 0.06) have beensynthesized by thesol-gel auto-combustion method. The XRD, FESEM, HRTEM,UV-Vis, FTIR, Raman spectroscopy, Photo Luminesce and Magnetic Properties analysis have been used to investigate structural, morphological, optical, Raman spectroscopy, Photo Luminesce and Magnetic Properties. Every sample contains a single-phase spinel structure, as confirmed by XRD.The substitution of Sm3+ ions is found to increase the lattice parameter from 8.258–8.248Å.A monotone diffraction peak (311) is visible near small angles of degrees (35.33 to 35.13). The Debye-Scherrer equation, the nanoparticles' crystallite size ranges from 35.357–54.778 nm.FE-SEMs reveal a spherical grain that groups and has a porous form, with particles 38.13 to 53.28 nmin size.HR-TEM micrographs illustrate spherical morphology and their average particle size decreases from 55.32 to 65.42 nm. The selected area electron diffraction (SAED) pattern confirms the crystal planes which were revealed from XRD calculations.The spinel structure was confirmed by FTIR spectroscopy, which found 414 cm-1 and 516 cm-1 vibrational band at the octahedral and tetrahedral sites.As the concentration of Sm3+ rises, the direct and indirect band gap energy values determined from UV-Vis show an increase and decrease.The generated NPs' semiconducting nature is confirmed by the strong correlation between the g-value and particle size change.Photoluminescence (PL) investigation shows that all processed samples have four bands.(i) peak centered at 412 nm, which is near-band edge emission and corresponds to the ultraviolet (UV) band,(ii) The violet band has a high-intensity peak at 434 nm,(iii) The blue band is related to a low-intensity, sharp peak located at 466 nm, and (iv) A broad peak at 502 nm with a very low intensity distinguishes the green band.The Raman spectroscopy investigation revealed that the CMBSF nanoparticles had a mixed spinel structure. The magnetic investigation shows that when the Sm content of ferrites increases, saturation magnetization drops from 39.86 to 33.16 emu/g.The sample's coercivity (Hc) increases from 16.06 to 21.90 KOe with Sm substitution.

Flash combustion prepared Sm and Co doped Sr hexaferrite for environmental applications

Nanotechnology is offering solutions to water contamination issues, as new techniques are needed to improve the removal of harmful compounds from water bodies. Despite previous reviews on this topic, nanotechnology is paving the way for more effective water treatment methods. Understanding the substitute influence of divalent Co2+ and rare earth elements Sm3+ on the structure, magnetic, and removal efficiency of hexagonal ferrites requires an understanding of a sequence of SrFe12O19, SrFe11.5Co0.5O19, Sr0.95Sm0.05Fe12O19, and Sr0.95Sm0.05Fe11.5Co0.5O19 M-type hexagonal ferrites were prepared using the flash technique. The XRD examination revealed that the crystallized material formed a single M-type hexagonal phase. The characteristics of M-type hexagonal ferrites include absorption bands with low wavenumbers in the FTIR curves between 400 to 1000 cm−1. There was a variation in magnetic characteristics with the replacement of Sm3+ and Co2+ doping, possibly due to the spin canting impact created by rare earth Sm3+ and Co2+ ions. The goal of the research is to explore the potential of doping magnetic hexaferrites and its influence in wastewater treatment. Various parameters, such as pH and contact duration, that influence the adsorption of lead ions from aqueous solutions were also examined. At pH 7 and 25 °C after 70min, the maximal removal efficiency of the Sr0.95Sm0.05Fe11.5Co0.5O19 was found to be 99%. Magnetic separation was carried out by applying an external magnetic field using a permanent magnet. The strong magnetization of the ferrites (51–58 emu/g) enabled the rapid separation of the magnetic particles from the solution, with over 95% of the ferrite particles being recovered within 10 to 70 min. The Freundlich isotherm model fitted all the isotherm data. Adsorption kinetics were explained by the pseudo-first-order, pseudo-second order, and intraparticle diffusion models. The investigated samples’ adsorption capacity remained efficient till 5 cycles.

Effect of Rare Earth Element Sm on Elastic Modulus and Crack Suppression of Cobalt-Based Alloys in Laser Cladding Applications

Effect of Rare Earth Element Sm on Elastic Modulus and Crack Suppression of Cobalt-Based Alloys in Laser Cladding Applications

Superior performance of asymmetric supercapacitor based on Cu doped bismuth ferrite electrode

Electrochemical energy storage devices, like supercapacitors and batteries, are needed to meet the constantly increasing demands of portable energy devices. Many types of supercapacitor electrodes were synthesized and reported which include carbon-based materials, polymers, oxides and perovskites. In this work, we report on the fabrication of Cu doped bismuth ferrite (Cu-BiFeO3, Cu-BFO) nanoparticles via sol-gel procedure. In most of the doping cases the costly rare earth elements like La, Nd, Sm, Ce and Yb are used to replace Bi. Electrodes of Bi1-xCuxFeO3 where x have the values 0.0, 0.025, 0.05, 0.075, 0.1 and 0.15 were deposited on graphitic sheets. Optimum Cu doping value was found to be at x = 0.05. Cu2+ ions doping in place of Bi3+ ions will reveal the roles of oxygen vacancies, as determined from XPS. The estimated values of specific capacitance was found to be 732 F/g at 0.5 A/g for the electrode at x = 0.05 in three electrode system. 5%Cu-BFO//Carbon black asymmetric supercapacitor (ASC) device can be charged and discharged reversibly at cell voltage of 0.0 up to 1.5 V when using a 0.5 M Na2SO4 aqueous electrolyte. This configuration allows the ASC device to deliver a great energy density of 37.25 Wh/kg at a power density of 752 W/kg. The ASC device demonstrates excellent cycling stability, retaining 88.64 % of its initial specific capacitance after 5000 cycles. Increasing the Cu content up to 15 % causes instability in the crystal structure of BFO resulting on phase segregation into Bi2Fe4O9 along with BFO and deterioration in the electrode overall performance. XPS showed that replacement of Cu2+ in place of Bi3+ disturbs the neutrality and the chemical environment of the compound. Hence to achieve neutrality and ionic balance, oxygen vacancies increase and the Fe2+/Fe3+ ratio increases as well. Both oxygen vacancies and the change in the Fe ions ratio reduce electrochemical impedance and give rise to charge density. The homogenous distribution of the pores at x = 0.05 contributed greatly to its fast electrolyte ion diffusion that improved the observed capacitive properties. One has to mention here, that despite doping that contains ions with different ionic size and/or different oxidation state is unfavorable, to some extent, due to the changes they produce in the electronic structure and the chemical environment, nevertheless it is sometimes beneficial in creating new parameters in the structure that promote specific application like in the case of the current work, oxygen vacancies, increase in surface area and the mixed state valency.

High Selectivity MEMS C2H2 Sensor for Transformer Fault Characteristic Gas Detection**

AbstractAcetylene (C2H2), as an important characteristic gas in transformer fault diagnosis, should be accurately detected and effectively distinguished from other dissolved gases (H2, CH4, C2H6, C2H4, CO, CO2), which is crucial to determine whether the fault occurs and the fault type, but also faces challenges now. The rational design and employment of rare earth and noble metals are expected to address this issue. In this work, SnO2‐3 at% Sm2O3‐1 at% PdO based MEMS gas sensor was prepared to achieve high performance detection of C2H2 which has a response value of 56 to 50 ppm C2H2, response/recovery time of 2 s/136 s, lower detection limit of 1 ppm, power consumption of 15.5 mW, and weak cross sensitivity to other transformer fault characteristic gases. Lewis acids and bases theory was used to explain the reason why rare earth Sm is a benefit element to improve selectivity to C2H2. The formation of oxygen vacancies and hetero junctions was used to explain the increased sensitivity of the material. This study proved the feasibility of rare earth and noble metals as potential additives to enable advanced gas‐sensitive materials for highly selective transformer fault characteristic gas C2H2 detection.

Effect of samarium on microstructure and mechanical properties of dilute Mg-Al-Ca alloys

To facilitate the industrial application of wrought Mg alloys, this study explores the impact of the rare earth (RE) element Sm on the microstructure and mechanical properties of hot-rolled Mg-1Al-0.3Ca alloy. The results indicate that the average grain size and basal texture intensity of the hot-rolled Mg-1Al-0.7Sm-0.3Ca alloy are significantly reduced compared to the hot-rolled Mg-1Al-0.3Ca alloy. This reduction can be attributed to the pinning effect of grain boundaries and grain refinement facilitated by the presence of the fine Al2Sm phase. Additionally, the addition of Sm leads to an increase in yield strength and ultimate tensile strength, along with a decrease in elongation. This can be attributed to the combined effects of the strengthening mechanism provided by a significant number of Al2Sm particles and the stress concentration occurring at the sharp corners of these particles. Significantly, this study proposes the substitution of expensive RE elements with more cost-effective Sm in the design of Mg alloys for low-alloy systems. The excellent mechanical properties of the Mg-1Al-0.7Sm-0.3Ca alloy provide a reference for the future development of high-performance Mg alloys.

Sb3+/Sm3+ Codoped Cs2NaScCl6 All-Inorganic Double Perovskite: Blue Emission of Self-Trapped Excitons and Red-Emission via Energy Transfer.

The lead-free halide perovskites possess nontoxicity and excellent chemical stability, whereas relatively weak luminescence intensity limits their potential in practical applications. Therefore, strengthening the luminescence intensity and expanding application fields are urgent tasks for the development of lead-free halide perovskites. In this paper, antimony-doped Cs2NaScCl6 crystals synthesized by a solvothermal method emit bright, deep blue photoluminescence at 447 nm. The photoluminescence (PL), photoluminescence excitation (PLE), and absorption spectra demonstrate that Sb3+ doping effectively activate the intrinsic "dark self-trapped exciton (STE)," leading to an impressive photoluminescence quantum yield (PLQY) value of 78.31% for 1% Sb3+ doping. Furthermore, the luminescence intensity remains above 92% compared with the fresh sample without secondary phases detected even after 90 days under environmental conditions. To expand the emission spectra, rare-earth Sm3+ is further incorporated into Cs2NaScCl6:1% Sb3+ crystals. The results show that Sb ions not only enhance intrinsic STE luminescence but also serve as sensitizers to boost the red-light emission of Sm3+, leading to a significant 500-fold increase in red emission intensity. Finally, the PLQY reaches a stunning 86.78%. These findings provide valuable insights in the design of Sb ion-doped lead-free double perovskites, broadening the application fields in various optoelectronic devices.

A closer look at the magnetic, photo-electrochemical, and optical properties of rare earth (Sm, Dy, Ho, Er, and Yb)-doped manganese ferrite for potential use as a photocatalyst

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

Strategy for co-enhancement of corrosion resistance-strength of Cu-7Ni-3Al-1Fe-1Mn alloy: Rare earth Sm microalloying

Both high strength and superior corrosion resistance are necessary for Cu-Ni alloys when serving in marine engineering. We discover that the corrosion resistance and strength of Cu-7Ni-3Al-1Fe-1Mn alloy can be enhanced via rare earth Sm microalloying. When Sm content is 33 ppm, the alloy exhibits not only the lowest corrosion rate, which is 40% lower than the Sm-free alloy, but also the maximum tensile strength, which is 6% higher than the Sm-free alloy. After alloying 33 ppm Sm, the average grain size of Cu-7Ni-3Al-1Fe-1Mn alloy is reduced by 42%, from 205 μm to 118 μm. In addition, CuSm phase and (Sm2S3-Al2O3) composite phase appear in the alloy after alloying 33 ppm Sm. The improvement of corrosion resistance is primarily due to the formation of Cu-Sm precipitates, leading to a positive shift of the corrosion potential. Further analysis indicates that the increased strength can be mainly attributed to grain refinement and the formation of Sm-S precipitations. This work promotes a new method for enhancing the strength and corrosion resistance simultaneously of copper alloy.

Doped rare earth elements enhance gas sensing properties of hollow spiral-like Mn(OH)F semiconductor sensors for acetate esters detection

This study successfully synthesized a series of Mn(OH)F hollow structures doped with rare earth elements (Sm, Nd, Ce, and Tb) using a hydrothermal method. A comprehensive analysis was conducted on the influence of these dopant elements on the morphology and gas-sensitive properties of Mn(OH)F. The gas-sensing performance of Mn(OH)F nanomaterials doped with Sm, Nd, Ce, and Tb was extensively investigated at 150℃ for methyl acetate, ethyl acetate, propyl acetate, and butyl acetate. The results demonstrated good gas-sensing capabilities, with responses reaching 2.0, 2.0, 2.0, and 2.5, respectively. Compared to undoped Mn(OH)F nanomaterials, the operating temperature of these sensors was reduced by about 100℃, and the response values were nearly tripled. Exceptional selectivity and stability were also observed. In addition, an in-depth exploration was conducted into the underlying mechanisms behind the enhanced gas response due to rare earth element doping. This study provides strong theoretical support for the development of efficient acetate ester gas sensors, demonstrating broad prospects for their widespread application in the industrial field.

Influence of ionic radius on the degree of extraction of rare earth metals during sorption by the interpolymer system AMBERLITE IR-120 –AВ-17-8

Studies have been carried out on the sorption of rare earth metal ions in solution using the interpolymer system Amberlite IR-120:AB-17-8. The purpose of the work is to search for conditions for maximum sorption of rare earth elements (Dy, Tb, Gd, Eu and Sm) from aqueous solutions using the effect of remote interaction of ion exchange resins. Methodology. The residual concentrations of rare earth ions were determined using an Optima 8300DV Duo inductively coupled plasma spectrometer. Results. The best sorption characteristics were determined by the interpolymer system at a ratio of 3:3. The residual concentration of rare earth elements in the solution was: Dy – 4.64 mg/l, Tb – 4.16 mg/l, Gd – 4.21 mg/l, Eu – 4.16 mg/l, Sm – 4.56 mg/l. The variations in the ionic radius of the ions chosen for the study are Dy3+<Tb3+<Gd3+<Eu3+<Sm3+. The degree of sorption of interpolymer system increased with increasing ionic radius of the metals. For dysprosium with the smallest ionic radius, the degree of sorption was η – 52%, and for terbium, gadolinium and europium it increased to η – 58%. For individual Amberlite IR-120 (6:0), the degree of sorption of terbium ions was 47%. Conclusion. The results of the study showed that the interpolymer system with a ratio of 3:3 has the best sorption activity. It has been established that the degree of sorption of interpolymer pairs increases with increasing order of the ionic radius of metals (Tb3+< Gd3+< Eu3+).

Perovskite-Derivative Ni-Based Catalysts for Hydrogen Production via Steam Reforming of Long-Chain Hydrocarbon Fuel

Large-scale hydrogen production by the steam reforming of long-chain hydrocarbon fuel is highly desirable for fuel-cell application. In this work, LaNiO3 perovskite materials doped with different rare earth elements (Ce, Pr, Tb and Sm) were prepared by a sol-gel method, and the derivatives supported Ni-based catalysts which were successfully synthesized by hydrogen reduction. The physicochemical properties of the as-prepared catalysts were characterized by powder X-ray diffraction, high-resolution transmission electron microscopy, N2 adsorption–desorption isotherms, H2 temperature-programmed reduction, and X-ray photoelectron spectroscopy. The catalytic performance of the as-prepared catalysts for hydrogen production was investigated via the steam reforming of n-dodecane. The results showed that the catalyst forms perovskite oxides after calcination with abundant mesopores and macropores. After reduction, Ni particles were uniformly distributed on perovskite derivatives, and can effectively reduce the particles’ sizes by doping with rare earth elements (Ce, Pr, Tb and Sm). Compared with the un-doped catalyst, the activity and hydrogen-production rate of the catalysts are greatly improved with rare earth element (Ce, Pr, Tb and Sm)-doped catalysts, as well as the anti-carbon deposition performance. This is due to the strong interaction between the uniformly distributed Ni particles and the support, as well as the abundant oxygen defects on the catalyst surface.

Intrinsic magnetism of an individual rare-earth atom on transition metal dichalcogenide semiconductors

Two-dimensional (2D) structures that exhibit intriguing magnetic phenomena such as perpendicular magnetocrystalline anisotropy (PMA) have become a focus of spintronic research due to their potentials in maximizing the information storage density. Herein we perform density-functional theory plus U (DFT+U) calculations to investigate the binding affinity and intrinsic magnetic properties of an individual rare-earth (RE) Sm atom on WSe2 monolayer. Our calculations show that Sm adatom energetically prefers to adsorb at the W-top site in WSe2 rather than the Se-top and hollow sites. We predict extremely large PMA values of ∼7–33 meV per Sm at the most stable W-top site, depending on U parameter in DFT+U calculations, while it is negligibly small for the Se-top and hollow sites. The underlying mechanism for large PMA is elucidated in terms of the strong spin–orbit coupled Sm 4f – W 5d orbital states and large 4f orbital magnetic moment in the high-spin crystal field. These results provide a viable route to achieving an atomic scale f-electron PMA in 2D structures, opening interesting prospects in two-dimensional semiconducting spintronics.

Rare-earth element doped barium titanate-based ceramics exhibiting ultra-wide temperature span electrocaloric effect

Electrocaloric effect (ECE) refrigeration stands out as a promising alternative to conventional compression refrigeration owing to its potential for miniaturization, high energy conversion efficiency, cost-effectiveness, and environmental friendliness. However, the practical applications of ECE refrigeration in lead-free ceramics face limitations due to the challenge of achieving a substantial adiabatic temperature change (ΔT) and a wide operating temperature span (Tspan). In this study, we tackle this challenge by introducing rare-earth Sm3+ ions into Ba(Ti0·90Sn0.10)O3 (BTSn) ceramics to enhance their ECE stability. We comprehensively investigate the structural, dielectric, and ECE properties of (Ba1−3x/2Smx) (Ti0·9Sn0.1)O3 (BSmTSn, x = 0−0.03) ceramics. Our findings reveal that the incorporation of Sm3+ ions leads to a reduction in the temperature at which the permittivity reaches its maximum, accompanied by an increased dispersion compared to undoped BTSn ceramics. Particularly noteworthy is the achievement of a ΔT of 0.9 K with a Tspan of 55.5 °C in the x = 0.005 composition. Furthermore, increasing x to 0.01 enables the realization of a wide Tspan of 70 °C, starting from 30 °C. These significant enhancements in the Tspan across all BSmTSn ceramics, facilitated by the introduction of Sm3+ ions, present a promising strategy for optimizing the ECE performance of BaTiO3-based ceramics.

Real-time control of distillation process to improve the recovery efficiency of ThF4-LiCl-KCl molten salt.

The purification and recovery of chloride electrolyte molten salts are vital to reuse this valuable species and reduce the waste. Vacuum distillation method was used to investigate the recovery efficiency of LiCl-KCl mixed molten salt containing 20 wt% ThF4. Rapid mass loss in the initial stage and the subsequent lower evaporation rate were significantly observed under 1173 K and 20 Pa due to the coordination species such as Li3ThF7 and LiTh2F9. To achieve the recovery efficiency of chloride salts, a real-time control distillation was proposed. The distillation was terminated when about 80% mixture salt was evaporated according to the transient weight loss curve. The evaporation ratio of LiCl-KCl reached 91% and the decontamination factors for Th and rare earth elements Nd and Sm were more than 103 and 102, respectively. The results provided a simple and effective scheme to separate ThF4 and recover molten salts from waste electrolyte salts.

Soil Improvement after Reclamation of Rare Earth Tailings in Northeast Guangdong, China

In order to explore the soil improvement effect of guest soil reclamation, the main physical and chemical properties of the soil in-situ extracted rare earth tailings after reclamation in Pingyuan County, Meizhou city were tested. Using 5 point sampling method, soil samples were taken from a 0-20 cm soil layer to detect NH4+ residues, pH value, content of organic matter, available N, available K, available P, and heavy metal in the soil. The results were shown that the NH4+ content in the soil decreased from 96.67 to 15.29 (mg·kg−1) after reclamation, the pH value increased from 4.58 to 5.40, and the organic matter increased from 2.12 to 2.75 (g·kg−1). However, the available N, P, and K decreased, and the soil fertility index also decreased from 0.55 to 0.49. The reclamation did not significantly improve soil fertility. The Nemero comprehensive index of non-rare earth heavy metal elements decreased from 0.58 to 0.44, but the pollution of non-rare earth heavy metals in the soil before and after reclamation was at a clean level, and there was no heavy metal pollution. The total RE (rare earth) content in tailings soil, reclaimed soil, and control soil was higher than the soil environmental background value in Guangdong Province. Heavy RE content in tailings soil exceeded 50% of total RE content, while light RE was mainly in the reclaimed soil. The pollution levels of total RE metals in soil before and after reclamation were non-pollution to moderate pollution level and non-pollution level, respectively. The control soil was the most severely polluted, reaching a strong pollution level. The three RE metals, Y, Sm and Ce, accounted for the highest proportion of the total soil REs, and the pollution levels of the latter two elements were above strong pollution in control soil. After 4 years of land reclamation, the NH4+-N pollution, soil acidification, and heavy metal pollution in the soil of tailings could be significantly improved, but the soil fertility was still low and required a long remediation process. In the future reclamation work, in addition to continuing to pay attention to the improvement of soil environment, the improvement of soil fertility and the control of RE pollution should also be strengthened, and when using foreign soil for reclamation and improvement, the quality of foreign soil, especially fertility, should also be considered.

Study on the structure, Mössbauer and magnetic properties of polycrystalline Mn-doped SmFeO3

SmFe1−xMnxO3 (x = 0.0, 0.1, 0.3) polycrystalline powder samples were prepared by sol-gel method, and the obtained samples were all orthorhombic structures with Pbnm space group. Mössbauer spectroscopy at room temperature confirmed the +3 oxidation state of iron. All samples were fitted by sextet spectra, indicating that the samples are magnetically ordered at room temperature. The zero-field-cooled and field-cooled curves of SmFe0.9Mn0.1O3 sample show a reverse crossover trend at 5 K，and the magnetization is significantly enhanced after reaching the spin-switching transition temperature (Tssw∼285 K). SmFe0.7Mn0.3O3 sample exhibits a second-order spin-reorientation transition in the temperature range of 236–281 K. Rare-earth Sm ions underwent a spin-ordered transition from a paramagnetic state to an antiferromagnetic state at around 8 K. Due to the Dzyaloshinskii-Moriya antisymmetric interaction, the M − H curves of the sample at 5 K and 300 K both exhibit weak ferromagnetism.