Journal of Rare Earths最新文献

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Giant low-field magnetocaloric effect in unstable antiferromagnetic Tm1–xErxNi2Si2 (x = 0.2, 0.4) compounds 不稳定反铁磁性 Tm1-xErxNi2Si2 (x = 0.2, 0.4) 化合物中的巨型低场磁ocaloric 效应
IF 5.2 1区 化学
Journal of Rare Earths Pub Date : 2025-02-01 DOI: 10.1016/j.jre.2023.12.017
Bo Xu , Lu Tian , Junfeng Wang , Mei Wu , Xinqiang Gao , Zhenxing Li , Jun Shen
{"title":"Giant low-field magnetocaloric effect in unstable antiferromagnetic Tm1–xErxNi2Si2 (x = 0.2, 0.4) compounds","authors":"Bo Xu ,&nbsp;Lu Tian ,&nbsp;Junfeng Wang ,&nbsp;Mei Wu ,&nbsp;Xinqiang Gao ,&nbsp;Zhenxing Li ,&nbsp;Jun Shen","doi":"10.1016/j.jre.2023.12.017","DOIUrl":"10.1016/j.jre.2023.12.017","url":null,"abstract":"<div><div>Magnetic refrigeration (MR) technology is regarded as an ideal solution for cryogenic applications, relying on magnetocaloric materials which provide necessary chilling effect. A series of polycrystalline Tm<sub>1–<em>x</em></sub>Er<sub><em>x</em></sub>Ni<sub>2</sub>Si<sub>2</sub> (<em>x</em> = 0.2, 0.4) compounds was synthesized, and their magnetic properties, magnetic phase transition together with magnetocaloric effect (MCE) were studied. The Tm<sub>1–<em>x</em></sub>Er<sub><em>x</em></sub>Ni<sub>2</sub>Si<sub>2</sub> (<em>x</em> = 0.2, 0.4) compounds display a field-induced metamagnetic transition from antiferromagnetic (AFM) to ferromagnetism (FM) in excess of 0.2 T, respectively. Meanwhile, the AFM ground state is unstable. Under the field change of 0–2 T, the values of maximal magnetic entropy change (<span><math><mrow><mo>−</mo><msubsup><mrow><mo>Δ</mo><mi>S</mi></mrow><mi>M</mi><mi>max</mi></msubsup></mrow></math></span>) and refrigerant capacity (RC) for Tm<sub>0.8</sub>Er<sub>0.2</sub>Ni<sub>2</sub>Si<sub>2</sub> compound are 17.9 J/(kg·K) and 83.5 J/kg, respectively. The large reversible MCE under low magnetic fields (≤2 T) indicates that Tm<sub>0.8</sub>Er<sub>0.2</sub>Ni<sub>2</sub>Si<sub>2</sub> compound can serve as potential candidate materials for cryogenic magnetic refrigeration.</div></div>","PeriodicalId":16940,"journal":{"name":"Journal of Rare Earths","volume":"43 2","pages":"Pages 312-318"},"PeriodicalIF":5.2,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139094920","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}
引用次数: 0
Microstructure and electrochemical hydrogen storage properties of nanosized doped La2Ti2O7 solid solutions 纳米级掺杂 La2Ti2O7 固溶体的微观结构和电化学储氢特性
IF 5.2 1区 化学
Journal of Rare Earths Pub Date : 2025-02-01 DOI: 10.1016/j.jre.2023.12.011
Guofang Zhang, Jianyi Xu, Shilong Sun, Yiming Li, Zhuocheng Liu, Ruihua Guo, Zhiyong Yang, Lu Bai, Yanghuan Zhang
{"title":"Microstructure and electrochemical hydrogen storage properties of nanosized doped La2Ti2O7 solid solutions","authors":"Guofang Zhang,&nbsp;Jianyi Xu,&nbsp;Shilong Sun,&nbsp;Yiming Li,&nbsp;Zhuocheng Liu,&nbsp;Ruihua Guo,&nbsp;Zhiyong Yang,&nbsp;Lu Bai,&nbsp;Yanghuan Zhang","doi":"10.1016/j.jre.2023.12.011","DOIUrl":"10.1016/j.jre.2023.12.011","url":null,"abstract":"<div><div>Hydrothermal-sintering method was employed to obtain pure and Li, Co, Mn, Cu and Zn doped La<sub>2</sub>Ti<sub>2</sub>O<sub>7</sub> solid solutions. The substitution sites of doping ions are discussed. X-ray diffraction (XRD) results indicate that the doped ions were incorporated into the lattice of La<sub>2</sub>Ti<sub>2</sub>O<sub>7</sub> successfully. Transmission electron microscopy (TEM) measurements prove that the doped ions with smaller radius induce the contraction of lattice. The results of UV and photoluminescence (PL) tests show that the doped ions cause the red-shift of band gap energies and enhance the concentrations of oxygen vacancies and defects. The electrochemical hydrogen storage properties of the samples were measured at 303 and 333 K, respectively. The discharge capacities of the doped samples keep growing by increasing the cycle number at 333 K. Meanwhile, the doped samples possess better kinetic performances than the pure La<sub>2</sub>Ti<sub>2</sub>O<sub>7</sub>. Among the samples, the Mn, Co and Li ions doped samples exhibit better electrochemical hydrogen storage properties. The hydrogen storage properties are closely related with the characteristics of doped ions, crystallite sizes, the content of the oxygen vacancies and defects in the lattice of La<sub>2</sub>Ti<sub>2</sub>O<sub>7</sub>.</div></div>","PeriodicalId":16940,"journal":{"name":"Journal of Rare Earths","volume":"43 2","pages":"Pages 354-361"},"PeriodicalIF":5.2,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139022451","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}
引用次数: 0
Structural, dielectric and magnetic properties of terbium doped strontium spinel ferrite (SrFe2O4) synthesized by sol-gel method 溶胶-凝胶法合成的掺铽尖晶石铁氧体(SrFe2O4)的结构、介电和磁性能
IF 5.2 1区 化学
Journal of Rare Earths Pub Date : 2025-02-01 DOI: 10.1016/j.jre.2023.12.002
Rifat Shaheen , Hafeez Ullah , M.M. Moharam , Ahmad M. Saeedi , Ebraheem Abdu Musad Saleh , Muhammad Ijaz , Adel A. El-Zahhar , Gamil A.A.M. Al-Hazmi , Sana Ullah Asif , Hafiz Muhammad Tahir
{"title":"Structural, dielectric and magnetic properties of terbium doped strontium spinel ferrite (SrFe2O4) synthesized by sol-gel method","authors":"Rifat Shaheen ,&nbsp;Hafeez Ullah ,&nbsp;M.M. Moharam ,&nbsp;Ahmad M. Saeedi ,&nbsp;Ebraheem Abdu Musad Saleh ,&nbsp;Muhammad Ijaz ,&nbsp;Adel A. El-Zahhar ,&nbsp;Gamil A.A.M. Al-Hazmi ,&nbsp;Sana Ullah Asif ,&nbsp;Hafiz Muhammad Tahir","doi":"10.1016/j.jre.2023.12.002","DOIUrl":"10.1016/j.jre.2023.12.002","url":null,"abstract":"<div><div>In this research work, sol-gel technique was employed to prepare the strontium based spinel ferrite nanoparticles (SrFe<sub>2</sub>O<sub>4</sub>) with different ratios of terbium (Tb). Different characterization techniques were used to investigate the structural, morphological, dielectric and magnetic properties of the prepared samples. X-ray diffraction (XRD) result suggests that face-centered cube spinel nanocrystalline structure is formed. Crystallite size of the SrFe<sub>2</sub>O<sub>4</sub> decreases with rising of Tb ratio. The morphology, shape and size of the SrFe<sub>2</sub>O<sub>4</sub> were examined by scanning electron microscopy (SEM) analysis and results reveal inhomogeneous distributions of the nanostructures with high agglomeration. The electrical resistivity of the SrFe<sub>2</sub>O<sub>4</sub> increases with rising of Tb ratio, which is confirmed from the cyclic voltammetry. It is observed that dielectric constant of all the samples decreases with the increasing frequency range. It is determined that the dielectric constants of the spinel ferrites are frequency dependent and decrease with increasing the frequency of applied electric field. The magnetic behavior of SrFe<sub>2</sub>O<sub>4</sub> with different ratios of Tb was studied and it is found that the saturation magnetization values of samples decrease with increase in the substitution of Tb<sup>3+</sup> at octahedral sites for Fe<sup>3+</sup>. This decrease in the values of <em>M</em><sub>s</sub> is also attributed to spin at surface of nanoparticles.</div></div>","PeriodicalId":16940,"journal":{"name":"Journal of Rare Earths","volume":"43 2","pages":"Pages 337-344"},"PeriodicalIF":5.2,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138554518","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}
引用次数: 0
Effects of rare-earth Pr3+-Dy3+ doping on structural, magnetic, optical and dielectric properties of Zn2Y hexaferrite 稀土 Pr3+-Dy3+ 掺杂对 Zn2Y 六价铁氧体结构、磁性、光学和介电性质的影响
IF 5.2 1区 化学
Journal of Rare Earths Pub Date : 2025-02-01 DOI: 10.1016/j.jre.2024.02.014
Ibrahim Mohammed , Mohamed E. El Sayed , Ali Shawabkeh , Mohammad N. Murshed , Ibtehaj F. Alshdoukhi , Zeinhom M. El-Bahy , J. Mohammed , A.K. Srivastava
{"title":"Effects of rare-earth Pr3+-Dy3+ doping on structural, magnetic, optical and dielectric properties of Zn2Y hexaferrite","authors":"Ibrahim Mohammed ,&nbsp;Mohamed E. El Sayed ,&nbsp;Ali Shawabkeh ,&nbsp;Mohammad N. Murshed ,&nbsp;Ibtehaj F. Alshdoukhi ,&nbsp;Zeinhom M. El-Bahy ,&nbsp;J. Mohammed ,&nbsp;A.K. Srivastava","doi":"10.1016/j.jre.2024.02.014","DOIUrl":"10.1016/j.jre.2024.02.014","url":null,"abstract":"<div><div>This study was conducted to investigate the properties of Pr<sup>3+</sup>-Dy<sup>3+</sup> doped Zn<sub>2</sub>Y-type hexaferrite for potential technological applications. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and field-emission scanning electron microscopy (FESEM) were used to analyze structural properties. The crystallite size in the synthesized samples varies between 57.54 and 68.57 nm. The vibrational bands at 400 and 600 cm<sup>−1</sup>, common to all hexaferrites, were confirmed through FTIR. The FESEM analysis reveals an agglomeration of magnetic grains and a decrease in the average grain size from 1.24 to 1.06 μm. The <em>M-H</em> loops show that, with <em>x</em> values of 0.0, 0.1, and 0.2, the saturation magnetization is determined to be 34.76, 34.23, and 32.52 emu/g, respectively. The corresponding coercivity values are 21.24, 30.39, and 33.99 Oe. UV–visible spectroscopy using Tauc theory reveals an increase in the optical band gap from 2.32 to 2.50 eV, indicating a tunable energy band structure by incorporating Pr<sup>3+</sup>-Dy<sup>3+</sup> ions. The dielectric constant increases, whereas AC conductivity decreases with increased Pr<sup>3+</sup>-Dy<sup>3+</sup> concentration. The obtained results suggest the potential suitability of these materials for various technological applications.</div></div>","PeriodicalId":16940,"journal":{"name":"Journal of Rare Earths","volume":"43 2","pages":"Pages 329-336"},"PeriodicalIF":5.2,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140007839","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}
引用次数: 0
Low-dose X-ray induced long afterglow NIR luminescence from Cr3+ doped Zn1–xCdxGa2O4 spinel solid solutions 掺杂 Cr3+ 的 Zn1-xCdxGa2O4 尖晶石固溶体的低剂量 X 射线诱导长余辉近红外发光
IF 5.2 1区 化学
Journal of Rare Earths Pub Date : 2025-02-01 DOI: 10.1016/j.jre.2023.12.006
Tingting Zhao , Wenzhi Sun , Shuya Wang , Wei Meng , Chunqing Fu , Xiaoyan Fu , Hongwu Zhang
{"title":"Low-dose X-ray induced long afterglow NIR luminescence from Cr3+ doped Zn1–xCdxGa2O4 spinel solid solutions","authors":"Tingting Zhao ,&nbsp;Wenzhi Sun ,&nbsp;Shuya Wang ,&nbsp;Wei Meng ,&nbsp;Chunqing Fu ,&nbsp;Xiaoyan Fu ,&nbsp;Hongwu Zhang","doi":"10.1016/j.jre.2023.12.006","DOIUrl":"10.1016/j.jre.2023.12.006","url":null,"abstract":"<div><div><span><span>The low-dose X-ray induced long afterglow </span>near infrared (NIR) luminescence from Cr</span><sup>3+</sup> doped Zn<sub>1–<em>x</em></sub>Cd<sub><em>x</em></sub>Ga<sub>2</sub>O<sub>4</sub><span> spinel solid solutions was investigated. The structure analysis shows the good formation of Zn</span><sub>1–<em>x</em></sub>Cd<sub><em>x</em></sub>Ga<sub>2</sub>O<sub>4</sub><span> spinel solid solutions, which possesses a cubic spinel structure with </span><em>Fd</em>3<em>m</em> space group. The formation of Zn<sub>1–<em>x</em></sub>Cd<sub><em>x</em></sub>Ga<sub>2</sub>O<sub>4</sub> spinel solid solutions induces the obvious increase of long afterglow near infrared luminescence excited by low-dose X-ray. When the content of doped Cd<sup>2+</sup><span> reaches 0.1, the low-dose X-ray induced long afterglow NIR luminescence is the maximum. More importantly, only 5 s X-ray irradiation can induce more than 6 h NIR afterglow emission, of which the afterglow luminescent intensity is still 5 times stronger than the background intensity after 6 h. The thermoluminescent results show that under the 5 s exposure of X-ray, the trap density of Zn</span><sub>0.9</sub>Cd<sub>0.1</sub>Ga<sub>2</sub>O<sub>4</sub>:Cr<sup>3+</sup> is much higher than that of ZnGa<sub>2</sub>O<sub>4</sub>:Cr<sup>3+</sup>. The replacement of Cd<sup>2+</sup> ions with large radius at Zn<sup>2+</sup> sites causes the increase of defects and dislocations, which results in the obvious increase of trap concentrations. And the addition of high-<em>z</em> number elements Cd<sup>2+</sup> would enhance the X-ray absorption of the solid solutions, which thus can be easily excited by low-dose X-ray. Zn<sub>0.9</sub>Cd<sub>0.1</sub>Ga<sub>2</sub>O<sub>4</sub>:1%Cr<sup>3+</sup><span> solid solution is a potential candidate of low-dose X-ray induced long afterglow luminescent materials.</span></div></div>","PeriodicalId":16940,"journal":{"name":"Journal of Rare Earths","volume":"43 2","pages":"Pages 246-252"},"PeriodicalIF":5.2,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138741594","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}
引用次数: 0
Construction of novel spherical ZnIn2S4–Ag–LaFeO3 heterostructures for enhancing photocatalytic efficiency 构建新型球形 ZnIn2S4-Ag-LaFeO3 异质结构以提高光催化效率
IF 5.2 1区 化学
Journal of Rare Earths Pub Date : 2025-02-01 DOI: 10.1016/j.jre.2024.02.002
Dongsheng Jia, Jiaxuan Pan, Dongliang Zhang, Mitang Wang, Ying Li
{"title":"Construction of novel spherical ZnIn2S4–Ag–LaFeO3 heterostructures for enhancing photocatalytic efficiency","authors":"Dongsheng Jia,&nbsp;Jiaxuan Pan,&nbsp;Dongliang Zhang,&nbsp;Mitang Wang,&nbsp;Ying Li","doi":"10.1016/j.jre.2024.02.002","DOIUrl":"10.1016/j.jre.2024.02.002","url":null,"abstract":"<div><div>Herein we report novel photocatalysts ZnIn<sub>2</sub>S<sub>4</sub>–Ag–LaFeO<sub>3</sub> with the core–shell structured materials prepared by hydrothermal method. In order to improve the efficiency of photocatalytic degradation of pollutants, LaFeO<sub>3</sub> was prepared by hydrothermal followed by calcination, and further Ag nanoparticle (NP) was loaded onto the spherical structure of LaFeO<sub>3</sub> by photolysis of silver nitrate, and finally the spherical ZnIn<sub>2</sub>S<sub>4</sub>–Ag–LaFeO<sub>3</sub> photocatalyst was prepared by hydrothermal method again. The structure and properties of the as-prepared materials were characterized by X-ray photoelectron spectroscopy, ultraviolet–visible absorption spectroscopy, X-ray diffraction, scanning electron microscopy and fluorescence spectra. The results show that the synthesized composite photocatalysts display a significant improvement in photocatalytic efficiency relative to the single LaFeO<sub>3</sub> and ZnIn<sub>2</sub>S<sub>4</sub> and form a core–shell structure. Furthermore, the effect of the ratio of each component on the photocatalytic efficiency was investigated in detail, and it is discovered that at an Methylene Blue (MB) concentration of 0.219 mol/L, the degradation rate of MB is 95% at 120 min using 0.02 g of catalyst with an ideal ZnIn<sub>2</sub>S<sub>4</sub>:Ag:LaFeO<sub>3</sub> ratio of 10:0.5:1. The possible mechanisms to improve the photocatalytic efficiency were explored.</div></div>","PeriodicalId":16940,"journal":{"name":"Journal of Rare Earths","volume":"43 2","pages":"Pages 295-303"},"PeriodicalIF":5.2,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139690005","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}
引用次数: 0
Temperature sensing performance of Er3+:Yb3+ co-doped CaF2 ceramic powders using near-infrared light 使用近红外线检测 Er3+:Yb3+ 共掺杂 CaF2 陶瓷粉末的温度传感性能
IF 5.2 1区 化学
Journal of Rare Earths Pub Date : 2025-02-01 DOI: 10.1016/j.jre.2024.01.005
Nikifor Rakov , Francisco Matias , Glauco S. Maciel
{"title":"Temperature sensing performance of Er3+:Yb3+ co-doped CaF2 ceramic powders using near-infrared light","authors":"Nikifor Rakov ,&nbsp;Francisco Matias ,&nbsp;Glauco S. Maciel","doi":"10.1016/j.jre.2024.01.005","DOIUrl":"10.1016/j.jre.2024.01.005","url":null,"abstract":"<div><div><span>Luminescent materials<span> for application in temperature sensing have caught a lot of interest in recent years. Particularly erbium (Er</span></span><sup>3+</sup><span><span>)-doped fluoride-based materials (EFM), which are readily accessible by near-infrared (NIR) excitation to produce efficient photon conversion. It has been established that </span>ytterbium (Yb</span><sup>3+</sup>) may improve the performance of EFMs in both bulk and nanostructured forms by energy transfer channels among rare-earth ions in interstitial clusters. In this work, a comprehensive analysis of the Er<sup>3+</sup>:Yb<sup>3+</sup>:CaF<sub>2</sub><span> crystalline structure, photoluminescence, and energy transfer from Yb</span><sup>3+</sup> to Er<sup>3+</sup><span> is presented for powders prepared by combustion synthesis. The Er</span><sup>3+</sup>:Yb<sup>3+</sup>:CaF<sub>2</sub><span> powders display exceptional photon down-shift and up-conversion when exposed to NIR light (</span><em>λ</em> = 975 nm). The luminescence spectral change of the NIR emission around 1.5 μm, which corresponds to the Er<sup>3+</sup> electronic transition <sup>4</sup>I<sub>13/2</sub> → <sup>4</sup>I<sub>15/2</sub>, was investigated in a temperature range of 298–423 K for application in temperature sensing of biological systems exploring the third biological window. The luminescence intensity ratio technique was applied to the thermally coupled Stark sublevels of states <sup>4</sup>I<sub>13/2</sub> and <sup>4</sup>I<sub>15/2</sub> with the highest estimated temperature relative sensitivity being around 0.4 %/K at 298 K.</div></div>","PeriodicalId":16940,"journal":{"name":"Journal of Rare Earths","volume":"43 2","pages":"Pages 253-261"},"PeriodicalIF":5.2,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139460157","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}
引用次数: 0
Design and preparation of a sintered Nd-Y-Fe-B magnet with high magnetic properties via multi-main-phase process and subsequent grain boundary diffusion 采用多主相法和晶界扩散法制备高磁性能Nd-Y-Fe-B烧结磁体
IF 5.2 1区 化学
Journal of Rare Earths Pub Date : 2025-02-01 DOI: 10.1016/j.jre.2023.11.015
Fugang Chen , Suxin Lu , Jie Wang , Yong Zhao , Wenqiang Zhao , Zhi Xu
{"title":"Design and preparation of a sintered Nd-Y-Fe-B magnet with high magnetic properties via multi-main-phase process and subsequent grain boundary diffusion","authors":"Fugang Chen ,&nbsp;Suxin Lu ,&nbsp;Jie Wang ,&nbsp;Yong Zhao ,&nbsp;Wenqiang Zhao ,&nbsp;Zhi Xu","doi":"10.1016/j.jre.2023.11.015","DOIUrl":"10.1016/j.jre.2023.11.015","url":null,"abstract":"<div><div>A sintered Nd-Y-Fe-B magnet was designed and manufactured by the multi-main-phase process. Unevenly distributed Y in the magnet decreases the adverse magnetic weakening effect of Y on the coercivity. Grain boundary diffusion process (GBDP) was conducted to further enhance the coercivity of the Nd-Y-Fe-B magnet. The coercivity increases significantly from 884 to 1741 kA/m after GBDP with Pr<sub>60</sub>Tb<sub>10</sub>Cu<sub>30</sub> alloy. The mechanism of the coercivity enhancement is discussed based on the microstructure analysis. Micromagnetic simulation reveals that when the diffused Tb-rich shell thickness is lower than 12 nm the <em>c</em>-plane shell (perpendicular to the <em>c</em>-axis) is much more effective in enhancing the coercivity than the side plane shell (parallel to the <em>c</em>-axis). But when the Tb-rich shell thickness is above 12 nm the side plane shell contributes more to the coercivity enhancement. The results in this work can help to design and manufacture Nd-Fe-B magnets with low cost and high magnetic properties.</div></div>","PeriodicalId":16940,"journal":{"name":"Journal of Rare Earths","volume":"43 2","pages":"Pages 304-311"},"PeriodicalIF":5.2,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138543590","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}
引用次数: 0
Characterization and acid leaching of rare earth elements in coal gangue using pretreatment of selective grinding, tailings discarding and alkali roasting 利用选择性研磨、尾矿丢弃和碱焙烧预处理煤矸石中稀土元素的表征和酸浸法
IF 5.2 1区 化学
Journal of Rare Earths Pub Date : 2025-02-01 DOI: 10.1016/j.jre.2024.02.018
Xiaorui Wang , Wei Cheng , Ruidong Yang , Jingkun Zang
{"title":"Characterization and acid leaching of rare earth elements in coal gangue using pretreatment of selective grinding, tailings discarding and alkali roasting","authors":"Xiaorui Wang ,&nbsp;Wei Cheng ,&nbsp;Ruidong Yang ,&nbsp;Jingkun Zang","doi":"10.1016/j.jre.2024.02.018","DOIUrl":"10.1016/j.jre.2024.02.018","url":null,"abstract":"<div><div>Co-associated rare earth elements (lanthanide and yttrium, REY) in coal and its by-products have been considered important potential nontraditional rare earth sources. In this study, a coal gangue sample collected from a coal processing plant in Jinsha County of Guizhou Province, southwest China, was used as the research object. The content, modes of occurrence, and extraction (acid leaching after pretreatment of selective grinding, tailings discarding, and alkali roasting) of REY from the sample were analyzed. The result shows that the content of REY (1038.26 μg/g) in pyrite and quartz is low but mainly enriched in kaolinite. Under the following conditions of a filling ratio of 40% (grinding media steel ball) and grinding time of 8 min, selective grinding pretreatment is applied to achieve 176.95 μg/g (yield 24.08%) and 1104.93 μg/g (yield 75.92%) of REY in +2 mm and −2 mm fractions, respectively. Thus, the −2 mm coal gangue fraction is selected, used as the feed, and roasted and leached with HCl. When Na<sub>2</sub>CO<sub>3</sub> and NaCl are separately used as roasting activators, the REY leaching ratios are 91.41% and 68.88%, respectively, under the optimum conditions. The contents of REY in the final leachate are 1010.02 and 761.08 μg/g when Na<sub>2</sub>CO<sub>3</sub> and NaCl are used, respectively. The two REY contents are relatively higher than the impurity ions in the leachate, which facilitates further REY separation. The mechanism study reveals that high-temperature roasting increases the pore size and the total pore area of the gangue, which promotes leachate penetration and improves reaction efficiency. In addition, roasting facilitates the reaction between the sodium salt activator and kaolinite and other aluminosilicate minerals in the coal gangue to generate soluble salts, thus releasing REY into the solution. The appropriate roasting temperature transforms the activator into a molten state. Thus, the reaction between coal gangue and activator is a solid–liquid reaction rather than a solid–solid reaction, which improves the efficiency of the chemical reaction.</div></div>","PeriodicalId":16940,"journal":{"name":"Journal of Rare Earths","volume":"43 2","pages":"Pages 384-396"},"PeriodicalIF":5.2,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140091909","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}
引用次数: 0
Recent advances of cerium compounds in functional coatings: Principle, strategies and applications 功能涂层中铈化合物的最新进展:原理、策略和应用
IF 5.2 1区 化学
Journal of Rare Earths Pub Date : 2025-02-01 DOI: 10.1016/j.jre.2024.03.017
Kai An , Youqiang Wang , Yi Sui , Yongquan Qing , Wei Tong , Xuezhao Wang , Changsheng Liu
{"title":"Recent advances of cerium compounds in functional coatings: Principle, strategies and applications","authors":"Kai An ,&nbsp;Youqiang Wang ,&nbsp;Yi Sui ,&nbsp;Yongquan Qing ,&nbsp;Wei Tong ,&nbsp;Xuezhao Wang ,&nbsp;Changsheng Liu","doi":"10.1016/j.jre.2024.03.017","DOIUrl":"10.1016/j.jre.2024.03.017","url":null,"abstract":"<div><div>Cerium (Ce) compounds have attracted considerable attention as key components in functional coatings due to their many outstanding properties. This work provides a comprehensive review of recent advances in the application of Ce in functional coatings. The role of Ce in the improvement of functional properties such as corrosion-resistance, self-healing, superhydrophobicity, wear-resistance, and UV shielding is reviewed from the perspective of functional mechanism and applied research. Furthermore, the strategies, processes, practical problems, and current challenges in the research of functional coatings containing Ce are summarized and discussed. The objective is to highlight the great potential of Ce in functional coatings, and to explore new applications of Ce in the development of novel coatings. Thus, this work aims to enhance the application value of Ce, solving the problem of unbalanced application of rare-earth elements.</div></div>","PeriodicalId":16940,"journal":{"name":"Journal of Rare Earths","volume":"43 2","pages":"Pages 227-245"},"PeriodicalIF":5.2,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140399976","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}
引用次数: 0
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