Pub Date : 2025-02-01DOI: 10.1016/j.jre.2024.07.017
Zhe Wang , Mengke Yuan , Juntao Gao , Hongru Hao , Jingwei Li , Lingling Xu , Zhe Lv , Bo Wei
Cation segregation on cathode surfaces plays a key role in determining the activity and operational stability of solid oxide fuel cells (SOFCs). The double perovskite oxide PrBa0.8Ca0.2Co2O5+δ (PBCC) has been widely studied as an active cathode but still suffer from serious detrimental segregations. To enhance the cathode stability, a PBCC derived A-site medium-entropy Pr0.6La0.1Nd0.1Sm0.1Gd0.1Ba0.8Ca0.2Co2O5+δ (ME-PBCC) oxide was prepared and its segregation behaviors were investigated under different conditions. Compared with initial PBCC oxide, the segregations of BaO and Co3O4 on the surface of ME-PBCC material are significantly suppressed, especially for Co3O4, which is attributed to its higher configuration entropy. Our results also confirm the improved electrochemical performance and structural stability of ME-PBCC material, enabling it as a promising cathode for SOFCs.
{"title":"Effective suppression of surface cation segregations on double perovskite oxides through entropy engineering","authors":"Zhe Wang , Mengke Yuan , Juntao Gao , Hongru Hao , Jingwei Li , Lingling Xu , Zhe Lv , Bo Wei","doi":"10.1016/j.jre.2024.07.017","DOIUrl":"10.1016/j.jre.2024.07.017","url":null,"abstract":"<div><div>Cation segregation on cathode surfaces plays a key role in determining the activity and operational stability of solid oxide fuel cells (SOFCs). The double perovskite oxide PrBa<sub>0.8</sub>Ca<sub>0.2</sub>Co<sub>2</sub>O<sub>5+<em>δ</em></sub> (PBCC) has been widely studied as an active cathode but still suffer from serious detrimental segregations. To enhance the cathode stability, a PBCC derived A-site medium-entropy Pr<sub>0.6</sub>La<sub>0.1</sub>Nd<sub>0.1</sub>Sm<sub>0.1</sub>Gd<sub>0.1</sub>Ba<sub>0.8</sub>Ca<sub>0.2</sub>Co<sub>2</sub>O<sub>5+<em>δ</em></sub> (ME-PBCC) oxide was prepared and its segregation behaviors were investigated under different conditions. Compared with initial PBCC oxide, the segregations of BaO and Co<sub>3</sub>O<sub>4</sub> on the surface of ME-PBCC material are significantly suppressed, especially for Co<sub>3</sub>O<sub>4</sub>, which is attributed to its higher configuration entropy. Our results also confirm the improved electrochemical performance and structural stability of ME-PBCC material, enabling it as a promising cathode for SOFCs.</div></div>","PeriodicalId":16940,"journal":{"name":"Journal of Rare Earths","volume":"43 2","pages":"Pages 345-353"},"PeriodicalIF":5.2,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141841873","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}
A 12-metal Zn(II)-Nd(III) cluster 1 (sizes: 1.8 nm × 2.0 nm × 2.0 nm) was synthesized from a long-chain type Schiff base ligand. It displays ratiometric fluorescence response to neopterin (Neo) with high selectivity and sensitivity, which can be expressed by the equation I545 nm/I1060 nm = A·[Neo]2 + B·[Neo] + C. 1 is used to quantitatively test Neo concentrations in fetal calf serum (FCS) and urine, and the recovery ranges are 98.57%–103.82% and 99.25%–103.50%, respectively, while the relative standard deviations (RSDs) are 7.89%–9.46% and 1.85%–4.16%, respectively. The limits of detection of 1 to Neo in FCS and urine are 0.034 and 0.021 μmol/L, respectively.
{"title":"Construction of a 12-metal Zn(II)-Nd(III) nanocluster for ratiometric fluorescence detection of inflammatory marker neopterin","authors":"Huanyin Yu, Xiaoping Yang, Xiaoli Lv, Xianfeng Huang","doi":"10.1016/j.jre.2024.08.003","DOIUrl":"10.1016/j.jre.2024.08.003","url":null,"abstract":"<div><div>A 12-metal Zn(II)-Nd(III) cluster <strong>1</strong> (sizes: 1.8 nm × 2.0 nm × 2.0 nm) was synthesized from a long-chain type Schiff base ligand. It displays ratiometric fluorescence response to neopterin (Neo) with high selectivity and sensitivity, which can be expressed by the equation <em>I</em><sub>545 nm</sub>/<em>I</em><sub>1060 nm</sub> = <em>A</em>·[Neo]<sup>2</sup> + <em>B</em>·[Neo] + <em>C</em>. <strong>1</strong> is used to quantitatively test Neo concentrations in fetal calf serum (FCS) and urine, and the recovery ranges are 98.57%–103.82% and 99.25%–103.50%, respectively, while the relative standard deviations (RSDs) are 7.89%–9.46% and 1.85%–4.16%, respectively. The limits of detection of <strong>1</strong> to Neo in FCS and urine are 0.034 and 0.021 μmol/L, respectively.</div></div>","PeriodicalId":16940,"journal":{"name":"Journal of Rare Earths","volume":"43 2","pages":"Pages 270-275"},"PeriodicalIF":5.2,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143144197","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}
Pub Date : 2025-02-01DOI: 10.1016/j.jre.2024.02.020
Hao Qin, Hui Wan, Guofeng Guan
Hydroisomerization of n-alkanes plays an important role in fuel and lubricants processing. Bifunctional catalysts with ultralow platinum loading have recently been reported successively for hydroisomerisation. Herein, the catalysts were prepared successfully with different methods to improve the catalytic performance. The conversion of 0.01%Pt1@CeOx/SAPO-11 prepared by co-calcination method (0.01%Pt1@CS-c) is 71.4%, 25% higher than the other prepared by precipitation method. The turnover frequency per active surface platinum site (TOFPt) of 0.01%Pt1@CS-c is as high as 13115 h–1. Revealed by the X-ray photoelectron spectroscopy (XPS) results, the quality of phase boundary/intersurface between ceria and zeolite is found significantly different. The conjunction quality of phase boundary directly affects the spillover rate of intermediate species, which further leads to an apparent activity difference. In addition, the possible role of ceria in the reaction is discussed, rather than just as a carrier for the active metal atoms.
{"title":"Unusual roles of ceria as the support of a single-atom catalyst in hydroisomerization of n-heptane: Phase boundary acts as transport channels between different active centers","authors":"Hao Qin, Hui Wan, Guofeng Guan","doi":"10.1016/j.jre.2024.02.020","DOIUrl":"10.1016/j.jre.2024.02.020","url":null,"abstract":"<div><div>Hydroisomerization of n-alkanes plays an important role in fuel and lubricants processing. Bifunctional catalysts with ultralow platinum loading have recently been reported successively for hydroisomerisation. Herein, the catalysts were prepared successfully with different methods to improve the catalytic performance. The conversion of 0.01%Pt1@CeOx/SAPO-11 prepared by co-calcination method (0.01%Pt1@CS-c) is 71.4%, 25% higher than the other prepared by precipitation method. The turnover frequency per active surface platinum site (TOFPt) of 0.01%Pt1@CS-c is as high as 13115 h<sup>–1</sup>. Revealed by the X-ray photoelectron spectroscopy (XPS) results, the quality of phase boundary/intersurface between ceria and zeolite is found significantly different. The conjunction quality of phase boundary directly affects the spillover rate of intermediate species, which further leads to an apparent activity difference. In addition, the possible role of ceria in the reaction is discussed, rather than just as a carrier for the active metal atoms.</div></div>","PeriodicalId":16940,"journal":{"name":"Journal of Rare Earths","volume":"43 2","pages":"Pages 276-283"},"PeriodicalIF":5.2,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140046233","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}
This study developed a pilot-scale process feeding with two different materials resulting from a column leaching process and acid mine drainage (AMD) streams to recover rare earth elements (REEs). A life cycle assessment (LCA) study was done to evaluate the environmental impacts of rare earth production from deleterious material in the form of highly contaminated leachate (HCL) and low-contaminated leachate (LCL). The results indicate that the main contributors to environmental categories that produce RE-hydroxide stages are NaOH and electricity. Also, oxalic acid, Na2CO3, and hydrochloric acid significantly contribute to the production stage of individual rare earth oxides (REOs), including solvent extraction (SX) and precipitation steps. The HCL route has higher environmental impacts than LCL due to higher chemical/energy and H2SO4 usage, so 468 and 292 kg of carbon dioxide are generated to produce 1 t of individual REOs from HCL and LCL routes, respectively. Moreover, the carbon dioxide emitted from the process, including the RE-hydroxide production, SX, and REOs production, is less than 10 t CO2. A sensitivity analysis was also performed to assess the changeability of the environmental footprints of the main inputs in the SX process, as the main stage has a higher contribution to the whole process. This LCA study is the first step toward understanding the environmental influence of new processing methods to produce REEs from coal by-products through a developed pilot-scale process.
{"title":"Innovative pilot-scale process for sustainable rare earth oxide production from coal byproducts: A comprehensive environmental impact assessment","authors":"Mohsen Rabbani , Joshua Werner , Ario Fahimi , Ehsan Vahidi","doi":"10.1016/j.jre.2024.04.004","DOIUrl":"10.1016/j.jre.2024.04.004","url":null,"abstract":"<div><div>This study developed a pilot-scale process feeding with two different materials resulting from a column leaching process and acid mine drainage (AMD) streams to recover rare earth elements (REEs). A life cycle assessment (LCA) study was done to evaluate the environmental impacts of rare earth production from deleterious material in the form of highly contaminated leachate (HCL) and low-contaminated leachate (LCL). The results indicate that the main contributors to environmental categories that produce RE-hydroxide stages are NaOH and electricity. Also, oxalic acid, Na<sub>2</sub>CO<sub>3</sub>, and hydrochloric acid significantly contribute to the production stage of individual rare earth oxides (REOs), including solvent extraction (SX) and precipitation steps. The HCL route has higher environmental impacts than LCL due to higher chemical/energy and H<sub>2</sub>SO<sub>4</sub> usage, so 468 and 292 kg of carbon dioxide are generated to produce 1 t of individual REOs from HCL and LCL routes, respectively. Moreover, the carbon dioxide emitted from the process, including the RE-hydroxide production, SX, and REOs production, is less than 10 t CO<sub>2</sub>. A sensitivity analysis was also performed to assess the changeability of the environmental footprints of the main inputs in the SX process, as the main stage has a higher contribution to the whole process. This LCA study is the first step toward understanding the environmental influence of new processing methods to produce REEs from coal by-products through a developed pilot-scale process.</div></div>","PeriodicalId":16940,"journal":{"name":"Journal of Rare Earths","volume":"43 2","pages":"Pages 397-404"},"PeriodicalIF":5.2,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140778915","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}
Pub Date : 2025-02-01DOI: 10.1016/j.jre.2024.01.012
Sung Gue Heo , Jae Yeol Yang , Soong Ju Oh , Seok-Jun Seo , Mi Hye Lee , Kyoung-Tae Park
The demand for neodymium (NdFeB) permanent magnets for electric vehicles and eco-friendly generators is increasing. However, NdFeB magnets contain rare earth elements (REEs), which are limited in supply. In this study, we performed an exchange reaction between magnesium halides (fluoride and chloride) and waste NdFeB scrap and then compared the characteristics of the extracted halides salts. The compositions of the ternary Mg fluoride (LiF:NaF:MgF2 = 50:40:10 in mole ratio) and chloride (LiCl:NaCl:MgCl2 = 10:50:40 in mole ratio) salts were thermodynamically determined for achieving low eutectic temperatures. The reactions between the NdFeB scrap powder (1–2 mm) and Mg halide salts were carried out at 1073 and 873 K for the fluoride and chloride systems, respectively, in an argon atmosphere. After the reaction, we separated Nd halide from the residual salt and evaluated the Nd-extraction rate. The phase formation of the salt was analyzed using X-ray diffraction (XRD), and the extraction rate of Nd was analyzed using inductively coupled plasma optical emission spectroscopy (ICP-OES). Nd was extracted in the form of Nd halide (NdF3 or NdCl3), and the extraction rates in the fluoride and chloride systems are 98.64% and 84.59%, respectively. Thus, the fluoride system is more effective than the chloride system for Nd extraction. Our study provides a comprehensive comparative analysis of the effectiveness of fluoride and chloride systems in extracting REEs from NdFeB magnet scrap. Our study findings can be used to develop an effective method for recycling magnet scraps.
{"title":"Extraction of rare earth elements from neodymium (NdFeB) magnet scrap using magnesium halides","authors":"Sung Gue Heo , Jae Yeol Yang , Soong Ju Oh , Seok-Jun Seo , Mi Hye Lee , Kyoung-Tae Park","doi":"10.1016/j.jre.2024.01.012","DOIUrl":"10.1016/j.jre.2024.01.012","url":null,"abstract":"<div><div>The demand for neodymium (NdFeB) permanent magnets for electric vehicles and eco-friendly generators is increasing. However, NdFeB magnets contain rare earth elements (REEs), which are limited in supply. In this study, we performed an exchange reaction between magnesium halides (fluoride and chloride) and waste NdFeB scrap and then compared the characteristics of the extracted halides salts. The compositions of the ternary Mg fluoride (LiF:NaF:MgF<sub>2</sub> = 50:40:10 in mole ratio) and chloride (LiCl:NaCl:MgCl<sub>2</sub> = 10:50:40 in mole ratio) salts were thermodynamically determined for achieving low eutectic temperatures. The reactions between the NdFeB scrap powder (1–2 mm) and Mg halide salts were carried out at 1073 and 873 K for the fluoride and chloride systems, respectively, in an argon atmosphere. After the reaction, we separated Nd halide from the residual salt and evaluated the Nd-extraction rate. The phase formation of the salt was analyzed using X-ray diffraction (XRD), and the extraction rate of Nd was analyzed using inductively coupled plasma optical emission spectroscopy (ICP-OES). Nd was extracted in the form of Nd halide (NdF<sub>3</sub> or NdCl<sub>3</sub>), and the extraction rates in the fluoride and chloride systems are 98.64% and 84.59%, respectively. Thus, the fluoride system is more effective than the chloride system for Nd extraction. Our study provides a comprehensive comparative analysis of the effectiveness of fluoride and chloride systems in extracting REEs from NdFeB magnet scrap. Our study findings can be used to develop an effective method for recycling magnet scraps.</div></div>","PeriodicalId":16940,"journal":{"name":"Journal of Rare Earths","volume":"43 2","pages":"Pages 371-376"},"PeriodicalIF":5.2,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139516314","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}
Pub Date : 2025-02-01DOI: 10.1016/j.jre.2023.12.017
Bo Xu , Lu Tian , Junfeng Wang , Mei Wu , Xinqiang Gao , Zhenxing Li , Jun Shen
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 Tm1–xErxNi2Si2 (x = 0.2, 0.4) compounds was synthesized, and their magnetic properties, magnetic phase transition together with magnetocaloric effect (MCE) were studied. The Tm1–xErxNi2Si2 (x = 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 () and refrigerant capacity (RC) for Tm0.8Er0.2Ni2Si2 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 Tm0.8Er0.2Ni2Si2 compound can serve as potential candidate materials for cryogenic magnetic refrigeration.
{"title":"Giant low-field magnetocaloric effect in unstable antiferromagnetic Tm1–xErxNi2Si2 (x = 0.2, 0.4) compounds","authors":"Bo Xu , Lu Tian , Junfeng Wang , Mei Wu , Xinqiang Gao , Zhenxing Li , 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}
Pub Date : 2025-02-01DOI: 10.1016/j.jre.2024.02.004
Shiyou Zhang, Fangyi Zhao, Shengqiang Liu, Zhen Song, Quanlin Liu
Rare earth-doped inorganic compounds contribute mostly to the family of persistent luminescent materials due to the versatile energy levels of rare earth ions. One of the key research aims is to match the trap level stemming from the doped rare earth ion or intrinsic defects to the electronic structure of the host, and therefore thermoluminescence measurement becomes a radical technology in studying trap depth, which is one of the significant parameters that determine the properties of persistent luminescence and photostimulated luminescence. However, the results of trap depth obtained by different thermoluminescence methods are quite different so that they are not comparable. Herein, we analyzed different thermoluminescence methods, selected and improved the traditional peak position method of Tm/500 to be E = (−0.94lnβ+30.09)kTm. Only the experimental heating rate (β) is needed additionally, but the accuracy is improved greatly in most cases. This convenient and accurate method will accelerate the discovery of novel rare earth-doped materials.
{"title":"An improved method to evaluate trap depth from thermoluminescence","authors":"Shiyou Zhang, Fangyi Zhao, Shengqiang Liu, Zhen Song, Quanlin Liu","doi":"10.1016/j.jre.2024.02.004","DOIUrl":"10.1016/j.jre.2024.02.004","url":null,"abstract":"<div><div><span><span>Rare earth-doped inorganic compounds contribute mostly to the family of persistent </span>luminescent materials<span><span> due to the versatile energy levels of rare earth ions. One of the key research aims is to match the trap level stemming from the doped rare earth ion or intrinsic defects to the electronic structure of the host, and therefore </span>thermoluminescence<span><span> measurement becomes a radical technology in studying trap depth, which is one of the significant parameters that determine the properties of persistent luminescence and photostimulated luminescence. However, the results of trap depth obtained by different </span>thermoluminescence<span> methods are quite different so that they are not comparable. Herein, we analyzed different thermoluminescence methods, selected and improved the traditional peak position method of </span></span></span></span><em>T</em><sub>m</sub>/500 to be <em>E</em> = (−0.94ln<em>β</em>+30.09)<em>kT</em><sub>m</sub><span>. Only the experimental heating rate (</span><em>β</em>) is needed additionally, but the accuracy is improved greatly in most cases. This convenient and accurate method will accelerate the discovery of novel rare earth-doped materials.</div></div>","PeriodicalId":16940,"journal":{"name":"Journal of Rare Earths","volume":"43 2","pages":"Pages 262-269"},"PeriodicalIF":5.2,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139876332","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}
Hydrothermal-sintering method was employed to obtain pure and Li, Co, Mn, Cu and Zn doped La2Ti2O7 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 La2Ti2O7 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 La2Ti2O7. 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 La2Ti2O7.
采用水热烧结法获得了纯的和掺杂了 Li、Co、Mn、Cu 和 Zn 的 La2Ti2O7 固溶体。讨论了掺杂离子的取代位点。X 射线衍射 (XRD) 结果表明，掺杂离子成功地融入了 La2Ti2O7 的晶格中。透射电子显微镜（TEM）测量证明，半径较小的掺杂离子会导致晶格收缩。紫外和光致发光（PL）测试结果表明，掺杂离子导致了带隙能量的红移，并提高了氧空位和缺陷的浓度。分别在 303 K 和 333 K 下测量了样品的电化学储氢特性。在 333 K 下，随着循环次数的增加，掺杂样品的放电容量不断增加。同时，掺杂样品比纯 La2Ti2O7 具有更好的动力学性能。其中，掺杂 Mn、Co 和 Li 离子的样品具有更好的电化学储氢性能。储氢性能与掺杂离子的特性、结晶尺寸、La2Ti2O7 晶格中氧空位和缺陷的含量密切相关。
{"title":"Microstructure and electrochemical hydrogen storage properties of nanosized doped La2Ti2O7 solid solutions","authors":"Guofang Zhang, Jianyi Xu, Shilong Sun, Yiming Li, Zhuocheng Liu, Ruihua Guo, Zhiyong Yang, Lu Bai, 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}
Pub Date : 2025-02-01DOI: 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
In this research work, sol-gel technique was employed to prepare the strontium based spinel ferrite nanoparticles (SrFe2O4) 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 SrFe2O4 decreases with rising of Tb ratio. The morphology, shape and size of the SrFe2O4 were examined by scanning electron microscopy (SEM) analysis and results reveal inhomogeneous distributions of the nanostructures with high agglomeration. The electrical resistivity of the SrFe2O4 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 SrFe2O4 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 Tb3+ at octahedral sites for Fe3+. This decrease in the values of Ms is also attributed to spin at surface of nanoparticles.
{"title":"Structural, dielectric and magnetic properties of terbium doped strontium spinel ferrite (SrFe2O4) synthesized by sol-gel method","authors":"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","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}
Pub Date : 2025-02-01DOI: 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
This study was conducted to investigate the properties of Pr3+-Dy3+ doped Zn2Y-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−1, 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 M-H loops show that, with x 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 Pr3+-Dy3+ ions. The dielectric constant increases, whereas AC conductivity decreases with increased Pr3+-Dy3+ concentration. The obtained results suggest the potential suitability of these materials for various technological applications.
{"title":"Effects of rare-earth Pr3+-Dy3+ doping on structural, magnetic, optical and dielectric properties of Zn2Y hexaferrite","authors":"Ibrahim Mohammed , Mohamed E. El Sayed , Ali Shawabkeh , Mohammad N. Murshed , Ibtehaj F. Alshdoukhi , Zeinhom M. El-Bahy , J. Mohammed , 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}
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