Journal of Rare Earths最新文献

{"title":"Insight into physical properties of lutetium-based double half-Heusler alloys LuXCo2Bi2 (X = V, Nb and Ta)","authors":"Saber Saad Essaoud ,&nbsp;Said Al Azar ,&nbsp;Ahmad A. Mousa ,&nbsp;Anas Y. Al-Reyahi ,&nbsp;Nabil Al Aqtash ,&nbsp;Mohammed Elamin Ketfi","doi":"10.1016/j.jre.2023.11.011","DOIUrl":"10.1016/j.jre.2023.11.011","url":null,"abstract":"<div><div>Based on the density functional theory, the double half-Heusler alloys LuXCo₂Bi₂ (X = V, Nb, and Ta) were studied to predict their structural, thermodynamic, thermoelectric, and optical characteristics. All the considered alloys are thermodynamically stable and have semiconductor behavior with indirect band gaps of 0.62, 0.75, and 0.8 eV for LuVCo₂Bi₂, LuNbCo₂Bi₂, and LuTaCo₂Bi₂, respectively. The investigated compounds exhibit semiconducting behavior with energy gaps below 0.8 eV. The impact of heat and pressure on thermodynamic coefficients was evaluated, and the influence of charge carriers on the temperature-dependent properties was studied using the semi-classical Boltzmann model. The studied compounds were characterized by their low lattice thermal conductivity at room temperature and low thermal expansion coefficient. These alloys exhibit substantial absorption coefficients in the ultraviolet (UV) light region, high optical conductivity, and high reflectivity in the visible light region, making them highly appealing materials for applications in the energy and electronics sectors.</div></div>","PeriodicalId":16940,"journal":{"name":"Journal of Rare Earths","volume":"43 1","pages":"Pages 199-208"},"PeriodicalIF":5.2,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138540087","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of divalent cations (Co2+ and Ni2+) on microstructure, physical properties and application of NdFeO3","authors":"M.M. Arman","doi":"10.1016/j.jre.2023.12.003","DOIUrl":"10.1016/j.jre.2023.12.003","url":null,"abstract":"<div><div>The nanocrystalline samples Nd_{1–<em>x</em>}M_<em>x</em>FeO₃ (<em>x</em> = 0.0 and 0.1; M: Co²⁺ and Ni²⁺) were prepared using the citrate combustion method. The X-ray diffraction (XRD) pattern confirmed that the nanoparticles were synthesized in an orthorhombic structure. The particle size of Nd_{1–<em>x</em>}M_<em>x</em>FeO₃ is in the range of 29–59 nm. The selected area electron diffraction (SAED) indicates the samples were prepared in a polycrystalline nature. The samples Nd_{1–<em>x</em>}M_<em>x</em>FeO₃ (<em>x</em> = 0.0 and 0.1; M: Co²⁺ and Ni²⁺) have antiferromagnetic behavior. The Fe³⁺ spins are aligned antiparallel, forming the antiferromagnetic (AFM) properties, which are affected by many factors such as the bond angle between the Fe³⁺ (Fe³⁺–O^2––Fe³⁺) and the Dzyaloshinskii-Moriya (D-M) interaction. The doping of Co²⁺ and Ni²⁺ ions in NdFeO₃ enhances the magnetic properties of the NdFeO₃. The saturation magnetization (<em>M</em>_s) of Nd_0.90Co_0.10FeO₃ increases 1.8 times more than that of NdFeO₃. The exchange bias field (<em>H</em>_EX) of the Co-doped sample is two times greater than that of NdFeO₃. The magnetic anisotropy constant (<em>K</em>) of the 10% Co-doped sample increases by 11 factors compared to that of NdFeO₃. The Tauc plot illustrates that the samples have a direct optical transition. The divalent cation substitution (Co²⁺ and Ni²⁺) decreases the optical band gap of NdFeO₃, leading to the recommendation of using the samples Nd_0.90Co_0.10FeO₃ and Nd_0.90Ni_0.10FeO₃ in photocatalysis of dye degradation from water. The removal efficiencies of Cr⁶⁺ at pH = 6 are 88.06%, 85.54%, and 85.52% for the samples NdFeO₃, Nd_0.90Co_0.10FeO₃, and Nd_0.90Ni_0.10FeO₃, respectively. The Freundlich isotherm mode is the best-fit model for NdFeO₃ to adsorb Cr⁶⁺ ions from aqueous solutions.</div></div>","PeriodicalId":16940,"journal":{"name":"Journal of Rare Earths","volume":"43 1","pages":"Pages 89-97"},"PeriodicalIF":5.2,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138554144","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Influence of rare earth doping on hydrogen absorption properties of Zr7V5Fe alloy","authors":"Shuang Yang ,&nbsp;Zifeng Luo ,&nbsp;Guo Yang ,&nbsp;Lijun Lv ,&nbsp;Linhua Xu ,&nbsp;Haiyan Leng ,&nbsp;Xingbo Han ,&nbsp;Jianhui Zhu ,&nbsp;Wei Liu ,&nbsp;Pengfei Zhu ,&nbsp;Jing Xu","doi":"10.1016/j.jre.2024.01.006","DOIUrl":"10.1016/j.jre.2024.01.006","url":null,"abstract":"<div><div>As a representative of non-evaporative getter, Zr–V–Fe has gained widespread attention due to its advantages including low activation temperatures and rapid hydrogen absorption rates. In this study, we investigated the impact of La and Ce doping on the thermodynamic, kinetic, and activation properties of Zr₇V₅Fe alloy. X-ray diffraction analysis shows that rare earth doping causes a decrease in the cell volume of both the ZrV₂ and <em>α</em>-Zr phases of Zr₇V₅Fe alloy, which results in an increase in the plateau pressure of the alloys. The kinetic curves illustrate that rare earth doping leads to a coarse <em>α</em>-Zr phases and a larger particle size after activation, resulting in a decrease in the hydrogen absorption kinetic properties. As for the activation process, the rare earth doped alloys exhibit excellent activation with shorter incubation periods. X-ray photoelectron spectroscopy investigations reveal that Zr and V are initially in a highly oxidized state. As the heating temperature increases, they undergo a transition from oxidation state to metal state. The content of metal Zr in rare earth doped alloys is higher than that in undoped alloys at 250 °C, primarily due to rare earth elements' affinity for oxygen.</div></div>","PeriodicalId":16940,"journal":{"name":"Journal of Rare Earths","volume":"43 1","pages":"Pages 218-226"},"PeriodicalIF":5.2,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139581593","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Magnetism and cryogenic magnetocaloric effect of triangular-lattice LnOF (Ln = Gd, Dy, Ho, and Er) compounds","authors":"Jianjian Gong ,&nbsp;Lu Tian ,&nbsp;Lei Zhang ,&nbsp;Zhaojun Mo ,&nbsp;Yuanpeng Wang ,&nbsp;Jun Shen","doi":"10.1016/j.jre.2023.10.005","DOIUrl":"10.1016/j.jre.2023.10.005","url":null,"abstract":"<div><div>Frustrated lanthanide oxides with dense magnetic lattice and suppressed ordering temperature have potential applications in cryogenic magnetic refrigeration. Herein, the crystal structure, magnetic properties, magnetic phase transition (MPT) together with magnetocaloric effect (MCE) of LnOF (Ln = Gd, Dy, Ho, and Er) compounds were investigated. Crystallographic study shows that these compounds crystallize in the centrosymmetric space group <span><math><mrow><mi>R</mi><mover><mn>3</mn><mo>¯</mo></mover><mi>m</mi></mrow></math></span> with an ideal triangular lattice. No long-range magnetic ordering is observed above 2 K for LnOF (Ln = Gd, Ho, and Er). However, DyOF compound undergoes an MPT from paramagnetic (PM) to antiferromagnetic (AFM) at the Néel temperature (<em>T</em>_N ≈ 4 K). Considerable reversible MCE is observed in these triangular-lattice compounds. Under the magnetic field change (<em>μ</em>₀Δ<em>H</em>) of 0–2 T, the maximum values of magnetic entropy change <span><math><mrow><mo>(</mo><mrow><mo>-</mo><mi>Δ</mi><msubsup><mi>S</mi><mtext>M</mtext><mtext>max</mtext></msubsup></mrow><mo>)</mo></mrow></math></span> of them are 6.1, 9.4, 12.7, and 14.1 J/(kg·K), respectively. Interestingly, the value of ErOF with Ising-like spin is 2.3 times that of GdOF, which provides an approach for exploring magnetic refrigerants with excellent low-field cryogenic magnetocaloric effect.</div></div>","PeriodicalId":16940,"journal":{"name":"Journal of Rare Earths","volume":"43 1","pages":"Pages 98-104"},"PeriodicalIF":5.2,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135706581","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Enhancement of weathered crust elution-deposited rare earth ores leaching process with PQ-10 addition","authors":"Aoyang Sha ,&nbsp;Huifang Yang ,&nbsp;Zhengyan He ,&nbsp;Zhigao Xu ,&nbsp;Chenjie Wu ,&nbsp;Ming Wu ,&nbsp;Ru'an Chi","doi":"10.1016/j.jre.2023.12.005","DOIUrl":"10.1016/j.jre.2023.12.005","url":null,"abstract":"<div><div>To solve the problems of the long development period, low mass transfer efficiency and high impurity content in the <em>in-situ</em> leaching process of weathered crust elution-deposited rare earth ores (WCE-DREO), cationic hydroxyethyl cellulose (PQ-10) was composited with conventional leaching agent ammonium sulfate ((NH₄)₂SO₄) to form a novel composite leaching agent. The effects of PQ-10 concentration, leaching temperature and leaching flow rate of the composite leaching agent on the leaching kinetics and mass transfer processes of rare earth (RE) and aluminum (Al) were investigated. Compared to the single leaching agent (NH₄)₂SO₄, the composite leaching agent (2 wt% (NH₄)₂SO₄+0.02 wt% PQ-10) can reduce the RE leaching equilibrium time from 465 to 130 min and increase the RE leaching efficiency and decrease the Al leaching efficiency. It also facilitates the leaching process of WCE-DREO by increasing the peak concentrations of RE and Al, reducing the theoretical tower plate height (HETP) and improving the leaching mass transfer efficiency. It is indicated that PQ-10 can promote the leaching of WCE-DREO. The leaching process of the composite leaching system conforms to the diffusion kinetic control model. When the PQ-10 concentration is in the range of 0.005 wt%<strong>–</strong>0.020 wt%, the reaction orders of RE and Al are 0.73 and 0.54, respectively, which shows a positive effect on the leaching velocity; when the PQ-10 concentration is in the range of 0.030 wt%<strong>–</strong>0.060 wt%, the reaction orders of RE and Al are <strong>–</strong>1.16 and <strong>–</strong>0.75, respectively, which show a negative effect on the leaching velocity. In the range of 10<strong>–</strong>50 °C, the apparent activation energies of RE and Al are 15.02 and 17.31 kJ/mol, respectively, and the higher the leaching temperature, the smaller the HETP and the higher the leaching velocity and mass transfer efficiency. The increase in leaching flow rate contributes to the increase in the longitudinal diffusion velocity of the leaching agent within WCE-DREO, causing a shorter time for RE and Al to reach leaching equilibrium. In addition, the flow rate and HETP are consistent with the Van Deemter equation. At a flow rate of 0.8 mL/min, HETP was minimized and the optimal mass transfer efficiencies is achieved for RE and Al.</div></div>","PeriodicalId":16940,"journal":{"name":"Journal of Rare Earths","volume":"43 1","pages":"Pages 180-190"},"PeriodicalIF":5.2,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138575206","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Tunable and wideband high-performance rare earth-doped Ni-Mg-Cu-Zn nano ferrite-based meta-absorbers for C-band application","authors":"Majid Niaz Akhtar ,&nbsp;Magbool Alelyani ,&nbsp;Fatimah Mohammed A. Alzahrani ,&nbsp;Abdullah Almohammedi ,&nbsp;Sabih Qamar ,&nbsp;M.A. Baqir ,&nbsp;M. Irfan ,&nbsp;Muhammad Azhar Khan ,&nbsp;Kheir S. Albarkaty ,&nbsp;Z.A. Alrowaili ,&nbsp;M.S. Al-Buriahi","doi":"10.1016/j.jre.2023.12.007","DOIUrl":"10.1016/j.jre.2023.12.007","url":null,"abstract":"<div><div>Due to advanced technology, electromagnet interference and dissipation problems in the electronic and portable devices at GHz range are increasing daily. Magnetic absorbing materials with outstanding electromagnetic properties, wide bandwidth, and strong absorption are highly desirable. The present investigation deals with the preparation of Ni-Mg-Cu-Zn (NMCZ) substituted nano ferrites with composition of Ni_0.3Mg_0.2Cu_0.3Zn_0.2X_0.02Fe_1.98O₄ (X = Nd, Ho, Pr, Gd, Yb). X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), a vibratory sample magnetometer (VSM), and a Vector network analyzer (VNA) were used to investigate these rare earth-doped nanocrystalline ferrites' features. XRD reveals the single spinel phase structure in all Ni-Mg-Cu-Zn ferrites. FTIR spectroscopy shows the presence of tetrahedral and octahedral bands of spinel ferrites. FESEM images reveal the lowest agglomeration for the Ho-doped NMCZ nano-spinel ferrites sample. TEM images show the hexagon shapes of the Yb- and Nd-doped NMCZ ferrites. Pr-doped NMCZ ferrites show more coercivity than other rare earth metals substituted NMCZ nanocrystalline ferrites. VSM analysis was used to calculate the magnetic features like initial permeability, magnetic anisotropy constant, remanence, coercivity, and magnetic moment. High-frequency switching field distributions (SFD) analyses were also investigated. Magnetodielectric characteristics such as losses, permittivity, modulus, <em>Q</em>, ac conductivity, and impedance of the Nd-, Ho-, Pr-, Gd-, Yb-doped Ni-Mg-Cu-Zn ferrites were evaluated. The minimum reflection loss (–57.3 dB) is found at 1.4 GHz for Pr-doped Ni-Mg-Cu-Zn ferrite absorber. However, the reflection loss (RL) of –53.9 dB at 2.9 GHz is observed for Ho-doped Ni-Mg-Cu-Zn ferrite absorber. Soft magnetization, low coercivity, outstanding magnetodielectric, and absorption properties of the Nd-, Ho-, Pr-, Gd- and Yb-doped Ni-Mg-Cu-Zn ferrites are suitable candidates for absorption in telecommunication, defense, and technological industries.</div></div>","PeriodicalId":16940,"journal":{"name":"Journal of Rare Earths","volume":"43 1","pages":"Pages 124-132"},"PeriodicalIF":5.2,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139022449","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Photoluminescence upgradation of La2MgTiO6:2%Dy3+ perovskite with monovalent (Li+), divalent (Ba2+, Sr2+) and trivalent (Bi3+, Sm3+) cation sensitization","authors":"V.P. Veena ,&nbsp;K. Arun ,&nbsp;C.K. Shilpa ,&nbsp;S.V. Jasira ,&nbsp;K.M. Nissamudeen","doi":"10.1016/j.jre.2023.12.013","DOIUrl":"10.1016/j.jre.2023.12.013","url":null,"abstract":"<div><div>Nano phosphors of 2% Dy³⁺ (wt%) doped La₂MgTiO₆ and monovalent/divalent/trivalent co-doped La_1.98Dy_0.02MgTiO₆:<em>x</em>%A^<em>y</em>+ (A^<em>y</em>+: Li⁺, Ba²⁺, Sr²⁺, Bi³⁺, and Sm³⁺; 0 ≤ <em>x</em> ≤ 2 wt%) were synthesized by combustion method. From the XRD data, it is deduced that an increase in the valency of co-dopant increases the crystallinity of the double perovskite orthorhombic nanocrystal structure. With an increase in co-dopant size, an elevation in optical bandgap is visible with the highest bandgap of 3.835 eV for Bi³⁺. The photo-absorption is monotonically broadened for Sr²⁺, Sm³⁺, and Li⁺ around 200–450 nm. Under 351 nm, Dy³⁺ triggered lattice shows major characteristic emission peaks at 480 nm (⁴F_9/2 → ⁶H_15/2), 574 nm (⁴F_9/2 → ⁶H_13/2), and 670 nm (⁴F_9/2 → ⁶H_11/2), leading to near white light emission with CIE coordinates (0.341, 0.376). Upon co-doping, the PL intensity is significantly increased with maximum emission for trivalent Sm³⁺, followed by divalent Sr²⁺ and monovalent Li ⁺ respectively. With increasing excitation wavelength, Sr²⁺ shows a dominated output and it is found that divalent Sr²⁺ is a potential co-dopant that could enhance luminescence intensity up to 6 times with a Sr²⁺ → Dy³⁺ energy transfer efficiency of 86%. It is specified that the CIE coordinates of Li⁺ co-doped samples show ideal white emission with color coordinates (0.333, 0.336). The concluding outcomes signify the noblest rare earth Sm³⁺ co-doping and thus Sm³⁺ → Dy³⁺ energy transfer mechanism is discussed in detail.</div></div>","PeriodicalId":16940,"journal":{"name":"Journal of Rare Earths","volume":"43 1","pages":"Pages 47-56"},"PeriodicalIF":5.2,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139067211","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Synergistic effects of constituents in rare earth-based composites: Enhanced structural, electrical and magnetic properties for water splitting applications","authors":"Chitralekha ,&nbsp;S. Shankar ,&nbsp;A.P. Singh","doi":"10.1016/j.jre.2024.01.018","DOIUrl":"10.1016/j.jre.2024.01.018","url":null,"abstract":"<div><div>Rare earth-based Bi_0.85La_0.15FeO₃ (BLFO) and NdMnO₃ (NMO) particles were synthesised using the solid-state route, and their roles affecting structural, electrical, magnetic properties along with hydroelectric application in different concentrations i.e., (1–<em>x</em>)BLFO:<em>x</em>NMO (where <em>x</em> = 0, 0.10, 0.20, 0.30 and 1.0) ceramics composites were investigated. X-ray diffraction analyses confirm the pure-phase formation of BLFO:NMO composites, featuring micrometer-scale crystallite sizes. Fourier transform infrared (FT-IR) spectra of BLFO:NMO composites reveal peak shifts with rising NMO content, indicating composite formation. These composites exhibit robust Maxwell–Wagner polarization and a pronounced composition-dependent behavior. The addition of NMO to BLFO results in a rise in dielectric permittivity at lower frequencies, confirming relaxor behavior and indicating success in achieving the transition temperature. Impedance spectroscopy facilitates a clearer understanding of how charge carriers contribute to these composites and the impact of grain/grain boundaries. The saturation magnetization maximum value (i.e., 0.807 emu/g) was attained in 0.7BLFO-0.3NMO. The coercivity decreases with the addition of NMO in BLFO. The results suggest the composite's enhanced suitability for microelectronics and hydropower cells, showing improved hydroelectric cell performance with increased NMO in BLFO, highlighting a notable ion diffusion mechanism.</div></div>","PeriodicalId":16940,"journal":{"name":"Journal of Rare Earths","volume":"43 1","pages":"Pages 105-114"},"PeriodicalIF":5.2,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139690266","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Selective recovery of rare earth elements by smelting of magnets","authors":"Venkata Lakshmi Borra ,&nbsp;Prasanta Jana ,&nbsp;P.P. Sahoo ,&nbsp;Prakash Venkatesan ,&nbsp;Mehmet Ali Recai Önal ,&nbsp;Chenna Rao Borra","doi":"10.1016/j.jre.2024.02.019","DOIUrl":"10.1016/j.jre.2024.02.019","url":null,"abstract":"<div><div>Rare earth elements (REEs) play a crucial role in many technologies from daily appliances in cell phones to more advanced wind turbines and electric cars. Permanent magnets account for a quarter of total global REEs production and have high recycling value. In this study, smelting process was used to selectively oxidize REEs in the permanent magnets by adding Fe₂O₃. This separates REEs into a slag phase from an iron-rich metallic phase. B₂O₃ was also added to the system as a flux to lower the slag melting temperature. This minimizes REEs loss to the metallic phase and allows a more efficient phase separation. The effect of flux and oxidizing agent addition was investigated on both regular and cerium-rich NdFeB (NdCeFeB) magnets. At 1350 °C and for 1 h, the slag phase was successfully separated from the metallic phase with the addition of 0.8 stoichiometric amount of Fe₂O₃ and 40 wt% of B₂O₃. Scanning electron microscopy–energy dispersive X-ray spectroscopy (SEM-EDX) analysis reveals that REEs in the magnet do not migrate to the metal phase while the REE-rich slag phase contains almost no iron. After the selective removal of iron into the metallic phase, REEs are recovered from the slag phase through an acid leaching process allowing &gt;99% of REEs recovery. Boron in the magnet can also be recovered as useful boric acid by evaporation and crystallisation technique. The proposed process in this study is reagent and energy-efficient with almost complete valorisation of both NdCeFeB and NdFeB magnets.</div></div>","PeriodicalId":16940,"journal":{"name":"Journal of Rare Earths","volume":"43 1","pages":"Pages 209-217"},"PeriodicalIF":5.2,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140125266","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Understanding amorphous PrOx-based N-doped carbon catalyst as an efficient electrocatalyst for oxygen reduction reaction","authors":"Xiao Man,&nbsp;Ying Chang,&nbsp;Shaohong Guo,&nbsp;Meilin Jia,&nbsp;Jingchun Jia","doi":"10.1016/j.jre.2024.04.005","DOIUrl":"10.1016/j.jre.2024.04.005","url":null,"abstract":"<div><div>The development of an efficacious and easily prepared nonprecious metal electrocatalyst is crucial for the oxygen reduction reaction (ORR). This work used a dual template method to prepare the amorphous rare earth-based catalyst PrO_<em>x</em>-NC, and optimized the calcination temperature and proportion. The PrO_<em>x</em>-NC-900 catalyst has high durability and activity and exhibits superior ORR performance in alkaline electrolytes with an onset potential (<em>E</em>₀) of 0.96 V and a half-wave potential (<em>E</em>_1/2) of 0.85 V. The research results indicate that the ORR performance of rare earth oxide composite carbon catalysts can be improved by adjusting oxygen vacancies (O_v). In addition, high specific surface area, N rich defect carbon, increased oxygen vacancies, and the synergistic effect of oxygen vacancies and N-doped carbon interfacial layer play a significant part in the enhancement of ORR. The performance of the zinc air battery assembled with PrO_<em>x</em>-NC-900 is significantly improved, and rare earth oxides and carbon frameworks originating from metal organic frameworks (MOFs) contribute to the oxygen electrocatalyst and electron transfer rate of the zinc air battery. This catalyst provides promising information for the development of rare earth metal oxide nanostructures as potential candidate materials for ORR in alkaline media.</div></div>","PeriodicalId":16940,"journal":{"name":"Journal of Rare Earths","volume":"43 1","pages":"Pages 73-80"},"PeriodicalIF":5.2,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140769067","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}