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 Pr60Tb10Cu30 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 c-plane shell (perpendicular to the c-axis) is much more effective in enhancing the coercivity than the side plane shell (parallel to the c-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.
{"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, Suxin Lu, Jie Wang, Yong Zhao, Wenqiang Zhao, Zhi Xu","doi":"10.1016/j.jre.2023.11.015","DOIUrl":"https://doi.org/10.1016/j.jre.2023.11.015","url":null,"abstract":"<p>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.</p>","PeriodicalId":16940,"journal":{"name":"Journal of Rare Earths","volume":"94 1","pages":""},"PeriodicalIF":4.9,"publicationDate":"2023-11-24","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}
Pub Date : 2023-11-23DOI: 10.1016/j.jre.2023.11.011
Saber Saad Essaoud, Said Al Azar, Ahmad A. Mousa, Anas Y. Al-Reyahi, Nabil Al Aqtash, Mohammed Elamin Ketfi
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.
{"title":"Insight into physical properties of lutetium-based double half-Heusler alloys LuXCo2Bi2 (X = V, Nb and Ta)","authors":"Saber Saad Essaoud, Said Al Azar, Ahmad A. Mousa, Anas Y. Al-Reyahi, Nabil Al Aqtash, Mohammed Elamin Ketfi","doi":"10.1016/j.jre.2023.11.011","DOIUrl":"https://doi.org/10.1016/j.jre.2023.11.011","url":null,"abstract":"<p>Based on the density functional theory, the double half-Heusler alloys LuXCo<sub>2</sub>Bi<sub>2</sub> (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 LuVCo<sub>2</sub>Bi<sub>2</sub>, LuNbCo<sub>2</sub>Bi<sub>2</sub>, and LuTaCo<sub>2</sub>Bi<sub>2</sub>, 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.</p>","PeriodicalId":16940,"journal":{"name":"Journal of Rare Earths","volume":"133 1","pages":""},"PeriodicalIF":4.9,"publicationDate":"2023-11-23","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}
Aluminum is the main impurity of the weathered crust elution-deposited rare earth ore (WCED-REO). Efficient leaching of rare earths and low leaching of aluminum are of great importance for the leaching of the WCED-REO. The effects of pH, MgSO4 concentration and Al3+ concentration of the leaching agent solution on the column leaching behaviors of WCED-REO using magnesium sulfate were investigated. Experimental data show that controlling the MgSO4 concentration to 0.15 mol/L, pH of the leaching agent solution to 2, the leaching amount of aluminum from the rare earth ore gradually decreases with the increase of Al3+ concentration in the leaching agent solution, indicating that Al3+ in the leaching agent solution may act as leaching agent to participate in the ion exchange of RE3+, but the leaching amounts of rare earths change insignificantly as the Al3+ concentration is increased. Increasing the MgSO4 concentration is beneficial to the leaching of aluminum, and when the Al3+ concentration is 0.04 mol/L (Al accumulation), the amount of Al3+ leached from the rare earth ore increased gradually with increasing the MgSO4 concentration. The pH of the leaching agent solution has a significant influence on the leaching of aluminum in the rare earth ore, and the leaching amount of aluminum from the rare earth ore increases gradually with decreasing the pH. When the Al3+ concentration is 0.04 mol/L (Al accumulation) and the pH of the leaching agent solution is above 2.0, the aluminum in the leaching agent solution can be back-adsorbed onto the rare earth ore, and the amount of the back-adsorbed Al3+ increases with increasing the pH of the leaching agent solution. The injection rate of the leaching agent solution has slight effect on the leaching behavior of rare earths and aluminum. In summary, leaching of Al3+ and consumption of MgSO4 can be reduced by regulating the accumulation of aluminum, MgSO4 concentration and pH.
{"title":"Leaching of rare earths and aluminum in weathered crust elution-deposited rare earth ore using magnesium sulfate: Effect of aluminum content in the leaching agent solution","authors":"Depeng Liu, Weiqiang Yin, Zheng Li, Jiaxin Pan, Longsheng Zhao, Chunmei Wang","doi":"10.1016/j.jre.2023.11.012","DOIUrl":"https://doi.org/10.1016/j.jre.2023.11.012","url":null,"abstract":"<p>Aluminum is the main impurity of the weathered crust elution-deposited rare earth ore (WCED-REO). Efficient leaching of rare earths and low leaching of aluminum are of great importance for the leaching of the WCED-REO. The effects of pH, MgSO<sub>4</sub> concentration and Al<sup>3+</sup> concentration of the leaching agent solution on the column leaching behaviors of WCED-REO using magnesium sulfate were investigated. Experimental data show that controlling the MgSO<sub>4</sub> concentration to 0.15 mol/L, pH of the leaching agent solution to 2, the leaching amount of aluminum from the rare earth ore gradually decreases with the increase of Al<sup>3+</sup> concentration in the leaching agent solution, indicating that Al<sup>3+</sup> in the leaching agent solution may act as leaching agent to participate in the ion exchange of RE<sup>3+</sup>, but the leaching amounts of rare earths change insignificantly as the Al<sup>3+</sup> concentration is increased. Increasing the MgSO<sub>4</sub> concentration is beneficial to the leaching of aluminum, and when the Al<sup>3+</sup> concentration is 0.04 mol/L (Al accumulation), the amount of Al<sup>3+</sup> leached from the rare earth ore increased gradually with increasing the MgSO<sub>4</sub> concentration. The pH of the leaching agent solution has a significant influence on the leaching of aluminum in the rare earth ore, and the leaching amount of aluminum from the rare earth ore increases gradually with decreasing the pH. When the Al<sup>3+</sup> concentration is 0.04 mol/L (Al accumulation) and the pH of the leaching agent solution is above 2.0, the aluminum in the leaching agent solution can be back-adsorbed onto the rare earth ore, and the amount of the back-adsorbed Al<sup>3+</sup> increases with increasing the pH of the leaching agent solution. The injection rate of the leaching agent solution has slight effect on the leaching behavior of rare earths and aluminum. In summary, leaching of Al<sup>3+</sup> and consumption of MgSO<sub>4</sub> can be reduced by regulating the accumulation of aluminum, MgSO<sub>4</sub> concentration and pH.</p>","PeriodicalId":16940,"journal":{"name":"Journal of Rare Earths","volume":"133 1","pages":""},"PeriodicalIF":4.9,"publicationDate":"2023-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138540085","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 : 2023-11-23DOI: 10.1016/j.jre.2023.11.013
Yikuan Hu , Jiajie Li , Shengyu Sun , Shuwei Zhong , Munan Yang , Xiaoqiang Yu , Sajjad Ur Rehman , Xi Yu
It is still a challenge to simultaneously enhance coercivity (Hcj) and remanence (Jr) of hot-deformed Nd-Fe-B magnet due to the coercivity-remanence trade-off dilemma. Here, we achieved this balance between Hcj and Jr by flake Cu powder assisted DyF3 interflake addition. The Hcj increases from 1218 to 1496 kA/m and Jr increases from 1.32 to 1.34 T compared with the original magnet. Results show that the width of coarse grain layers reduces because of the introduction of flake Cu, which increases the contact areas of the adjacent grains at ribbon interfaces and suppresses the excessive growth of grains. The stronger degree of texture and higher density compared with the original magnet should take the responsibility for the increase of Jr. Additionally, the aggregation regions of rare earth rich (RE-rich) phase reduce and the betterment of the microstructure is another reason for the enhancement of Jr in the flake Cu aided DyF3 hot-deformed magnet. This strategy of using flake powder additives provides a promising method for optimizing microstructure and enhancing magnetic properties of hot-deformed Nd-Fe-B magnets.
{"title":"Simultaneously enhancing coercivity and remanence of hot-deformed Nd-Fe-B magnets by flake copper powder assisted DyF3 interflake addition","authors":"Yikuan Hu , Jiajie Li , Shengyu Sun , Shuwei Zhong , Munan Yang , Xiaoqiang Yu , Sajjad Ur Rehman , Xi Yu","doi":"10.1016/j.jre.2023.11.013","DOIUrl":"10.1016/j.jre.2023.11.013","url":null,"abstract":"<div><p>It is still a challenge to simultaneously enhance coercivity (<em>H</em><sub>cj</sub>) and remanence (<em>J</em><sub>r</sub>) of hot-deformed Nd-Fe-B magnet due to the coercivity-remanence trade-off dilemma. Here, we achieved this balance between <em>H</em><sub>cj</sub> and <em>J</em><sub>r</sub> by flake Cu powder assisted DyF<sub>3</sub> interflake addition. The <em>H</em><sub>cj</sub> increases from 1218 to 1496 kA/m and <em>J</em><sub>r</sub> increases from 1.32 to 1.34 T compared with the original magnet. Results show that the width of coarse grain layers reduces because of the introduction of flake Cu, which increases the contact areas of the adjacent grains at ribbon interfaces and suppresses the excessive growth of grains. The stronger degree of texture and higher density compared with the original magnet should take the responsibility for the increase of <em>J</em><sub>r</sub>. Additionally, the aggregation regions of rare earth rich (RE-rich) phase reduce and the betterment of the microstructure is another reason for the enhancement of <em>J</em><sub>r</sub> in the flake Cu aided DyF<sub>3</sub> hot-deformed magnet. This strategy of using flake powder additives provides a promising method for optimizing microstructure and enhancing magnetic properties of hot-deformed Nd-Fe-B magnets.</p></div>","PeriodicalId":16940,"journal":{"name":"Journal of Rare Earths","volume":"42 7","pages":"Pages 1282-1288"},"PeriodicalIF":5.2,"publicationDate":"2023-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138540086","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 : 2023-11-14DOI: 10.1016/j.jre.2023.11.006
Polymeric nanoparticles of poly(methyl methacrylate) were obtained by emulsion polymerization techniques in a process of two stages. The particles were functionalized with acrylic acid, curcumin, and fumaramide and three series of polymeric particles were obtained. The incorporation of functional groups was confirmed by Fourier transform-infrared spectrosocopy (FT-IR) and ultraviolet–visible (UV–Vis) methods. The spherical morphology of particles with an average diameter of 100 nm was observed by scanning electron microscopy (SEM). The polymeric materials were used for recovery of [Eu] from synthetic solutions. The nanoparticles show excellent chelation capacity to trap rare-earth ions, because they recover more than 85% of [Eu] at pH of 2. The images of SEM after extraction process show arrays between particles with larger average particle sizes to 1.5 μm. In addition, the particles have a good stripping capacity, exceeding 50% of it, maintaining their homogeneity in morphology and good stability in dispersion for the recovery and stripping processes. A pseudo-second model order is obtained for the extraction and stripping processes while the best results of stripping process are obtained at pH of 6.
{"title":"Europium recovery process by means of polymeric nanoparticles functionalized with acrylic acid, curcumin and fumaramide","authors":"","doi":"10.1016/j.jre.2023.11.006","DOIUrl":"10.1016/j.jre.2023.11.006","url":null,"abstract":"<div><div>Polymeric nanoparticles of poly(methyl methacrylate) were obtained by emulsion polymerization techniques in a process of two stages. The particles were functionalized with acrylic acid, curcumin, and fumaramide and three series of polymeric particles were obtained. The incorporation of functional groups was confirmed by Fourier transform-infrared spectrosocopy (FT-IR) and ultraviolet–visible (UV–Vis) methods. The spherical morphology of particles with an average diameter of 100 nm was observed by scanning electron microscopy (SEM). The polymeric materials were used for recovery of [Eu] from synthetic solutions. The nanoparticles show excellent chelation capacity to trap rare-earth ions, because they recover more than 85% of [Eu] at pH of 2. The images of SEM after extraction process show arrays between particles with larger average particle sizes to 1.5 μm. In addition, the particles have a good stripping capacity, exceeding 50% of it, maintaining their homogeneity in morphology and good stability in dispersion for the recovery and stripping processes. A pseudo-second model order is obtained for the extraction and stripping processes while the best results of stripping process are obtained at pH of 6.</div></div>","PeriodicalId":16940,"journal":{"name":"Journal of Rare Earths","volume":"42 10","pages":"Pages 1950-1959"},"PeriodicalIF":5.2,"publicationDate":"2023-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135764022","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 : 2023-11-13DOI: 10.1016/j.jre.2023.11.007
Azra Haroon , Kaseed Anwar , Arham S. Ahmed
Ce-doped WO3 nanoparticles were successfully synthesized by the sol–gel method and characterized through advanced characterization techniques. The high resolution transmission electron microscopy (HRTEM) and scanning electron microscopy (SEM) results show a reduction in the agglomeration of nanoparticles upon doping. The energy dispersive X-ray (EDX) analysis validates the existence of the Ce element in all the doped samples. X-ray photoelectron spectroscopy (XPS) and Raman spectra justify the presence of structural defects (oxygen vacancies) and successful formation of the monoclinic WO3 phase, respectively. The Kubelka–Munk function indicates a decrease in band gap with doping, while photoluminescence (PL) spectra show intense visible and UV emissions. Significantly, all doped samples exhibit higher photocatalytic performance than pure WO3 nanoparticles, with the 6 wt% Ce-doped sample displaying the highest degradation rate. Doping with Ce can help to increase the surface area of WO3, thereby improving its photoactivity. Moreover, a correlation between PL and photocatalysis is established in the light of oxygen vacancies suggesting a direct dependence of high photocatalytic activity on strong PL signals of WO3 nanostructures. Trapping experiments further reveal that the degradation process is primarily driven by active species, providing insight into a plausible photocatalytic mechanism.
采用溶胶-凝胶法成功合成了掺杂 Ce 的 WO3 纳米粒子，并通过先进的表征技术对其进行了表征。高分辨率透射电子显微镜（HRTEM）和扫描电子显微镜（SEM）结果表明，掺杂后纳米粒子的团聚减少。能量色散 X 射线（EDX）分析验证了所有掺杂样品中都存在 Ce 元素。X 射线光电子能谱 (XPS) 和拉曼光谱分别证明了结构缺陷（氧空位）的存在和单斜 WO3 相的成功形成。库伯卡-蒙克（Kubelka-Munk）函数表明带隙随着掺杂而减小，而光致发光（PL）光谱则显示出强烈的可见光和紫外线辐射。值得注意的是，与纯 WO3 纳米粒子相比，所有掺杂样品都具有更高的光催化性能，其中掺杂 6 wt% Ce 的样品具有最高的降解率。掺杂 Ce 有助于增加 WO3 的表面积，从而提高其光活性。此外，在氧空位的作用下，聚光和光催化之间建立了相关性，这表明高光催化活性直接依赖于 WO3 纳米结构的强聚光信号。捕获实验进一步揭示了降解过程主要是由活性物种驱动的，从而深入了解了一种合理的光催化机制。
{"title":"Visible light-driven photo remediation of hazardous cationic dye via Ce-doped WO3 nanostructures","authors":"Azra Haroon , Kaseed Anwar , Arham S. Ahmed","doi":"10.1016/j.jre.2023.11.007","DOIUrl":"10.1016/j.jre.2023.11.007","url":null,"abstract":"<div><p>Ce-doped WO<sub>3</sub> nanoparticles were successfully synthesized by the sol–gel method and characterized through advanced characterization techniques. The high resolution transmission electron microscopy (HRTEM) and scanning electron microscopy (SEM) results show a reduction in the agglomeration of nanoparticles upon doping. The energy dispersive X-ray (EDX) analysis validates the existence of the Ce element in all the doped samples. X-ray photoelectron spectroscopy (XPS) and Raman spectra justify the presence of structural defects (oxygen vacancies) and successful formation of the monoclinic WO<sub>3</sub> phase, respectively. The Kubelka–Munk function indicates a decrease in band gap with doping, while photoluminescence (PL) spectra show intense visible and UV emissions. Significantly, all doped samples exhibit higher photocatalytic performance than pure WO<sub>3</sub> nanoparticles, with the 6 wt% Ce-doped sample displaying the highest degradation rate. Doping with Ce can help to increase the surface area of WO<sub>3</sub>, thereby improving its photoactivity. Moreover, a correlation between PL and photocatalysis is established in the light of oxygen vacancies suggesting a direct dependence of high photocatalytic activity on strong PL signals of WO<sub>3</sub> nanostructures. Trapping experiments further reveal that the degradation process is primarily driven by active species, providing insight into a plausible photocatalytic mechanism.</p></div>","PeriodicalId":16940,"journal":{"name":"Journal of Rare Earths","volume":"42 5","pages":"Pages 869-878"},"PeriodicalIF":4.9,"publicationDate":"2023-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135715540","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 : 2023-11-10DOI: 10.1016/j.jre.2023.11.005
Rare earth-based superlattice alloys have great potential for gaseous hydrogen storage, as well as successful application as nickel-metal hydride batteries anodes. In this work, Y substitution was carried out to adjust the gaseous hydrogen storage properties of A2B7-type La0.7Mg0.3Ni3.5 alloys. The results indicate a multiphase structure in the alloys comprised of the main rhombohedral Gd2Co7 and PuNi3 phases, with a small amount of CaCu5 phase. Moreover, the Y substitution results in higher abundance of the Gd2Co7 phase. The alloy La0.42Y0.28Mg0.3Ni3.5 exhibits a hydrogen storage capacity of 1.55 wt% at 298 K and a desorption plateau pressure of 0.244 MPa. In addition, this alloy demonstrates a stable cycle life by a capacity retention of 94.2% after 50 cycles, with the main capacity degradation occurring during the initial 20 cycles. This work accentuates the potential of the La–Y–Mg–Ni-based superlattice alloys for applications in solid-state hydrogen storage.
{"title":"Compositional tuning of A2B7-type La0.7–xYxMg0.3Ni3.5 alloys for gaseous hydrogen storage","authors":"","doi":"10.1016/j.jre.2023.11.005","DOIUrl":"10.1016/j.jre.2023.11.005","url":null,"abstract":"<div><div>Rare earth-based superlattice alloys have great potential for gaseous hydrogen storage, as well as successful application as nickel-metal hydride batteries anodes. In this work, Y substitution was carried out to adjust the gaseous hydrogen storage properties of A<sub>2</sub>B<sub>7</sub>-type La<sub>0.7</sub>Mg<sub>0.3</sub>Ni<sub>3.5</sub> alloys. The results indicate a multiphase structure in the alloys comprised of the main rhombohedral Gd<sub>2</sub>Co<sub>7</sub> and PuNi<sub>3</sub> phases, with a small amount of CaCu<sub>5</sub> phase. Moreover, the Y substitution results in higher abundance of the Gd<sub>2</sub>Co<sub>7</sub> phase. The alloy La<sub>0.42</sub>Y<sub>0.28</sub>Mg<sub>0.3</sub>Ni<sub>3.5</sub> exhibits a hydrogen storage capacity of 1.55 wt% at 298 K and a desorption plateau pressure of 0.244 MPa. In addition, this alloy demonstrates a stable cycle life by a capacity retention of 94.2% after 50 cycles, with the main capacity degradation occurring during the initial 20 cycles. This work accentuates the potential of the La–Y–Mg–Ni-based superlattice alloys for applications in solid-state hydrogen storage.</div></div>","PeriodicalId":16940,"journal":{"name":"Journal of Rare Earths","volume":"42 10","pages":"Pages 1912-1919"},"PeriodicalIF":5.2,"publicationDate":"2023-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135614028","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 : 2023-11-10DOI: 10.1016/j.jre.2023.10.016
Soil remediation containing numerous organic contaminants is of great significance to ecological environment. Herein, the synergetic effects of Ce–Mn/Al2O3 with different active components on catalytic thermal desorption of chlorobenzene in soil were investigated. The optimized Ce–Mn/Al2O3 drastically enhance the desorption efficiency of chlorobenzene, and the corresponding conversion reaches 100% within 1 h at a low temperature of 120 °C. The superior performance is ascribed to the formation of Ce–Mn solid solution during the calcination process, resulting in a certain lattice change to the generation of abundant oxygen vacancies and acidic sites. Combining with the analysis of in-situ diffuse reflectance infrared spectroscopy and gas chromatography-mass spectrometry, the final products of chlorobenzene are decomposed into CO2, H2O, Cl2 and HCl. This work sheds light on the rational design of highly-active catalysts for practical applications of sustainable soil remediation.
{"title":"Constructing Ce–Mn/Al2O3 with different active components for low temperature catalytic degradation of chlorobenzene in soil","authors":"","doi":"10.1016/j.jre.2023.10.016","DOIUrl":"10.1016/j.jre.2023.10.016","url":null,"abstract":"<div><div>Soil remediation containing numerous organic contaminants is of great significance to ecological environment. Herein, the synergetic effects of Ce–Mn/Al<sub>2</sub>O<sub>3</sub> with different active components on catalytic thermal desorption of chlorobenzene in soil were investigated. The optimized Ce–Mn/Al<sub>2</sub>O<sub>3</sub> drastically enhance the desorption efficiency of chlorobenzene, and the corresponding conversion reaches 100% within 1 h at a low temperature of 120 °C. The superior performance is ascribed to the formation of Ce–Mn solid solution during the calcination process, resulting in a certain lattice change to the generation of abundant oxygen vacancies and acidic sites. Combining with the analysis of <em>in-situ</em> diffuse reflectance infrared spectroscopy and gas chromatography-mass spectrometry, the final products of chlorobenzene are decomposed into CO<sub>2</sub>, H<sub>2</sub>O, Cl<sub>2</sub> and HCl. This work sheds light on the rational design of highly-active catalysts for practical applications of sustainable soil remediation.</div></div>","PeriodicalId":16940,"journal":{"name":"Journal of Rare Earths","volume":"42 10","pages":"Pages 1873-1881"},"PeriodicalIF":5.2,"publicationDate":"2023-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135614353","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 : 2023-11-10DOI: 10.1016/j.jre.2023.11.002
The present study focuses on the synthesis and characterization of lanthanum (La3+)-doped calcium nanoferrites (CaLaxFe2–xO4; x = 0.025, 0.050, 0.075 and 0.100) using the sonochemical method. Various techniques were employed to analyze the effect of La3+ infusion. Raman spectroscopy confirms the presence of active A1g, T2g and Eg modes in the CaLaxFe2–xO4 nanoferrite, indicating the formation of an active ferrite system. The introduction of La3+ doping results in a significant increase in the band gap energy, rendering the nanoferrites insulating (3.23–3.57 eV). At higher frequencies, the impedance studies reveal minimal losses and better AC conductivity, pointing to improved dielectric characteristics. At higher frequencies, the Q-factor of La-doped calcium nanoferrites shows lower electromagnetic losses. The M–H curve exhibits ferromagnetic behavior, with La3+-doped calcium nanoferrites displaying a saturation magnetization ranging from 12.72 to 18.10 emu/g. The incorporation of La3+ also induces enhanced electrical polarization, leading to notable dielectric loss and increased absorption of electromagnetic waves. Consequently, these CaLaxFe2–xO4 nanoferrites demonstrate potential as effective microwave absorbers across a wide frequency range, with significant shielding absorption observed at 8.8–9.1 GHz.
{"title":"Exploring the electromagnetic shielding behavior of lanthanum doped calcium nanoferrites","authors":"","doi":"10.1016/j.jre.2023.11.002","DOIUrl":"10.1016/j.jre.2023.11.002","url":null,"abstract":"<div><div><span>The present study focuses on the synthesis and characterization of lanthanum (La</span><sup>3+</sup>)-doped calcium nanoferrites (CaLa<sub><em>x</em></sub>Fe<sub>2–<em>x</em></sub>O<sub>4</sub>; <em>x</em> = 0.025, 0.050, 0.075 and 0.100) using the sonochemical method. Various techniques were employed to analyze the effect of La<sup>3+</sup><span> infusion. Raman spectroscopy confirms the presence of active </span><em>A</em><sub>1g</sub>, <em>T</em><sub>2g</sub> and <em>E</em><sub>g</sub> modes in the CaLa<sub><em>x</em></sub>Fe<sub>2–<em>x</em></sub>O<sub>4</sub> nanoferrite, indicating the formation of an active ferrite system. The introduction of La<sup>3+</sup><span> doping results in a significant increase in the band gap energy<span>, rendering the nanoferrites insulating (3.23–3.57 eV). At higher frequencies, the impedance studies reveal minimal losses and better AC conductivity, pointing to improved dielectric characteristics. At higher frequencies, the </span></span><em>Q</em>-factor of La-doped calcium nanoferrites shows lower electromagnetic losses. The <em>M</em>–<em>H</em> curve exhibits ferromagnetic behavior, with La<sup>3+</sup><span>-doped calcium nanoferrites displaying a saturation magnetization ranging from 12.72 to 18.10 emu/g. The incorporation of La</span><sup>3+</sup><span> also induces enhanced electrical polarization, leading to notable dielectric loss<span> and increased absorption of electromagnetic waves. Consequently, these CaLa</span></span><sub><em>x</em></sub>Fe<sub>2–<em>x</em></sub>O<sub>4</sub> nanoferrites demonstrate potential as effective microwave absorbers across a wide frequency range, with significant shielding absorption observed at 8.8–9.1 GHz.</div></div>","PeriodicalId":16940,"journal":{"name":"Journal of Rare Earths","volume":"42 11","pages":"Pages 2128-2136"},"PeriodicalIF":5.2,"publicationDate":"2023-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135609200","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 : 2023-11-09DOI: 10.1016/j.jre.2023.11.004
In this study, the mechanism of the reduction-diffusion reaction in a Sm–Fe binary system at low temperature was studied to investigate the possibility of synthesis of a Fe-rich TbCu7-type SmFex (x > 9) by the low-temperature diffusion-reduction (LTRD) process using LiCl–KCl eutectic molten salts. Firstly, the Sm–Fe phase transformation depending on the Sm–Fe composition, the LTRD temperature, and time was investigated, and it is found that the obtained metastable phase is only TbCu7-type SmFe∼8.5, which is not a Fe-rich phase. This Fe content does not change even after an expended LTRD process, and the metastable TbCu7-type SmFe∼8.5 tends to transform to the stable Sm2Fe17 phase. In addition, it is found that the Sm–Fe phase starts to synthesize from the Sm-rich phase in the order of SmFe2, SmFe3, and SmFe8.5 as the LTRD temperature increases (when the time was 10 h) or the LTRD time increases (when the temperature was 550 °C). Core-shell-like particles are observed in the case of a short LTRD time, and the core and the shell are Fe and the Sm-rich Sm–Fe phase, respectively, indicating that the Sm-rich phase begins to produce on the surface of the Fe particles. It is difficult to synthesize a Fe-rich TbCu7-type SmFex (x > 9) phase with the Sm–Fe binary system, suggesting that a different approach, such as addition of other elements, will be necessary.
{"title":"Mechanism of reduction-diffusion reaction in Sm–Fe binary system at low temperature using molten salts","authors":"","doi":"10.1016/j.jre.2023.11.004","DOIUrl":"10.1016/j.jre.2023.11.004","url":null,"abstract":"<div><div>In this study, the mechanism of the reduction-diffusion reaction in a Sm–Fe binary system at low temperature was studied to investigate the possibility of synthesis of a Fe-rich TbCu<sub>7</sub>-type SmFe<sub><em>x</em></sub> (<em>x</em> > 9) by the low-temperature diffusion-reduction (LTRD) process using LiCl–KCl eutectic molten salts. Firstly, the Sm–Fe phase transformation depending on the Sm–Fe composition, the LTRD temperature, and time was investigated, and it is found that the obtained metastable phase is only TbCu<sub>7</sub>-type SmFe<sub>∼8.5</sub>, which is not a Fe-rich phase. This Fe content does not change even after an expended LTRD process, and the metastable TbCu<sub>7</sub>-type SmFe<sub>∼8.5</sub> tends to transform to the stable Sm<sub>2</sub>Fe<sub>17</sub> phase. In addition, it is found that the Sm–Fe phase starts to synthesize from the Sm-rich phase in the order of SmFe<sub>2</sub>, SmFe<sub>3</sub>, and SmFe<sub>8.5</sub> as the LTRD temperature increases (when the time was 10 h) or the LTRD time increases (when the temperature was 550 °C). Core-shell-like particles are observed in the case of a short LTRD time, and the core and the shell are Fe and the Sm-rich Sm–Fe phase, respectively, indicating that the Sm-rich phase begins to produce on the surface of the Fe particles. It is difficult to synthesize a Fe-rich TbCu<sub>7</sub>-type SmFe<sub><em>x</em></sub> (<em>x</em> > 9) phase with the Sm–Fe binary system, suggesting that a different approach, such as addition of other elements, will be necessary.</div></div>","PeriodicalId":16940,"journal":{"name":"Journal of Rare Earths","volume":"42 10","pages":"Pages 1889-1894"},"PeriodicalIF":5.2,"publicationDate":"2023-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135565287","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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