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}
Pub Date : 2025-02-01DOI: 10.1016/j.jre.2023.12.006
Tingting Zhao , Wenzhi Sun , Shuya Wang , Wei Meng , Chunqing Fu , Xiaoyan Fu , Hongwu Zhang
The low-dose X-ray induced long afterglow near infrared (NIR) luminescence from Cr3+ doped Zn1–xCdxGa2O4 spinel solid solutions was investigated. The structure analysis shows the good formation of Zn1–xCdxGa2O4 spinel solid solutions, which possesses a cubic spinel structure with Fd3m space group. The formation of Zn1–xCdxGa2O4 spinel solid solutions induces the obvious increase of long afterglow near infrared luminescence excited by low-dose X-ray. When the content of doped Cd2+ 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 Zn0.9Cd0.1Ga2O4:Cr3+ is much higher than that of ZnGa2O4:Cr3+. The replacement of Cd2+ ions with large radius at Zn2+ sites causes the increase of defects and dislocations, which results in the obvious increase of trap concentrations. And the addition of high-z number elements Cd2+ would enhance the X-ray absorption of the solid solutions, which thus can be easily excited by low-dose X-ray. Zn0.9Cd0.1Ga2O4:1%Cr3+ solid solution is a potential candidate of low-dose X-ray induced long afterglow luminescent materials.
研究了掺杂 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现象。结构分析表明 Zn1-xCdxGa2O4 尖晶石固溶体形成良好，具有 Fd3m 空间群的立方尖晶石结构。Zn1-xCdxGa2O4 尖晶石固溶体的形成明显增加了低剂量 X 射线激发的长余辉近红外发光。当掺杂 Cd2+ 的含量达到 0.1 时，低剂量 X 射线激发的长余辉近红外发光达到最大值。更重要的是，仅 5 秒的 X 射线照射就能诱发超过 6 小时的近红外余辉发射，其中 6 小时后的余辉发光强度仍比背景强度强 5 倍。热释光结果表明，在 5 s 的 X 射线照射下，Zn0.9Cd0.1Ga2O4:Cr3+ 的阱密度远高于 ZnGa2O4:Cr3+。在 Zn2+ 位点上置换大半径的 Cd2+ 离子会导致缺陷和位错的增加，从而使陷阱浓度明显增加。而高 Z 数元素 Cd2+ 的加入会增强固溶体对 X 射线的吸收，因此很容易被低剂量 X 射线激发。Zn0.9Cd0.1Ga2O4:1%Cr3+ 固溶体是低剂量 X 射线诱导长余辉发光材料的潜在候选材料。
{"title":"Low-dose X-ray induced long afterglow NIR luminescence from Cr3+ doped Zn1–xCdxGa2O4 spinel solid solutions","authors":"Tingting Zhao , Wenzhi Sun , Shuya Wang , Wei Meng , Chunqing Fu , Xiaoyan Fu , 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}
Pub Date : 2025-02-01DOI: 10.1016/j.jre.2024.02.002
Dongsheng Jia, Jiaxuan Pan, Dongliang Zhang, Mitang Wang, Ying Li
Herein we report novel photocatalysts ZnIn2S4–Ag–LaFeO3 with the core–shell structured materials prepared by hydrothermal method. In order to improve the efficiency of photocatalytic degradation of pollutants, LaFeO3 was prepared by hydrothermal followed by calcination, and further Ag nanoparticle (NP) was loaded onto the spherical structure of LaFeO3 by photolysis of silver nitrate, and finally the spherical ZnIn2S4–Ag–LaFeO3 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 LaFeO3 and ZnIn2S4 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 ZnIn2S4:Ag:LaFeO3 ratio of 10:0.5:1. The possible mechanisms to improve the photocatalytic efficiency were explored.
{"title":"Construction of novel spherical ZnIn2S4–Ag–LaFeO3 heterostructures for enhancing photocatalytic efficiency","authors":"Dongsheng Jia, Jiaxuan Pan, Dongliang Zhang, Mitang Wang, 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}
Pub Date : 2025-02-01DOI: 10.1016/j.jre.2024.01.005
Nikifor Rakov , Francisco Matias , Glauco S. Maciel
Luminescent materials for application in temperature sensing have caught a lot of interest in recent years. Particularly erbium (Er3+)-doped fluoride-based materials (EFM), which are readily accessible by near-infrared (NIR) excitation to produce efficient photon conversion. It has been established that ytterbium (Yb3+) 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 Er3+:Yb3+:CaF2 crystalline structure, photoluminescence, and energy transfer from Yb3+ to Er3+ is presented for powders prepared by combustion synthesis. The Er3+:Yb3+:CaF2 powders display exceptional photon down-shift and up-conversion when exposed to NIR light (λ = 975 nm). The luminescence spectral change of the NIR emission around 1.5 μm, which corresponds to the Er3+ electronic transition 4I13/2 → 4I15/2, 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 4I13/2 and 4I15/2 with the highest estimated temperature relative sensitivity being around 0.4 %/K at 298 K.
{"title":"Temperature sensing performance of Er3+:Yb3+ co-doped CaF2 ceramic powders using near-infrared light","authors":"Nikifor Rakov , Francisco Matias , 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}
Pub Date : 2025-02-01DOI: 10.1016/j.jre.2023.11.015
Fugang Chen , Suxin Lu , Jie Wang , Yong Zhao , Wenqiang Zhao , Zhi Xu
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":"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}
Pub Date : 2025-02-01DOI: 10.1016/j.jre.2024.02.015
Na Jiang, Weiwei Wang, Haoxin Liu, Meiyao Wu, Chunjiang Jia
The activation of CO2 molecules is a fundamental step for their effective utilization. Constructing high-density oxygen vacancies on the surface of reducible oxides is pivotal for the activation of CO2. In this work, we prepared a series of 0.5PtxCe/Al2O3 (x=1, 5, 10, or 20) catalysts with varying Ce loading and 0.5 wt% of Pt for the reverse water gas shift (RWGS) reaction. The size of CeO2 particle increases with Ce loading. Remarkably, the 0.5Pt5Ce/Al2O3 catalyst with an average CeO2 particle size of 5.5 nm exhibits a very high CO2 conversion rate (116.4×10−5 molCO2/(gcat·s)) and CO selectivity (96.1%) at 600 °C. Our experimental findings reveal that the small-size CeO2 in 0.5Pt5Ce/Al2O3 possesses a greater capacity to generate reactive oxygen vacancies, promoting the adsorption and activation of CO2. In addition, the oxygen vacancies are cyclically generated and consumed during the reaction, which contributes to the elevated catalytic performance of the catalyst. This work provides a general strategy to construct rich oxygen vacancies on CeO2 for designing high-performance catalysts in C1 chemistry.
一氧化碳分子的活化是其有效利用的基本步骤。在可还原氧化物表面构建高密度氧空位是活化 CO 的关键。在这项工作中，我们制备了一系列 0.5PtCe/AlO ( = 1、5、10 或 20) 催化剂，这些催化剂中 Ce 的含量和 0.5 wt% 的 Pt 的含量各不相同，用于反向水煤气变换（RWGS）反应。CeO 颗粒的尺寸随 Ce 用量的增加而增大。值得注意的是，平均 CeO 粒径为 5.5 nm 的 0.5Pt5Ce/AlO 催化剂在 600 °C 时表现出极高的 CO 转化率（116.4 × 10 mol/（g-s））和 CO 选择性（96.1%）。我们的实验结果表明，0.5Pt5Ce/AlO 中的小尺寸 CeO 具有更强的生成活性氧空位的能力，从而促进了 CO 的吸附和活化。此外，氧空位在反应过程中循环生成和消耗，这有助于提高催化剂的催化性能。这项工作提供了一种在 CeO 上构建富氧空位的通用策略，用于设计高性能的 C 化学催化剂。
{"title":"Alumina supported platinum-ceria catalyst for reverse water gas shift reaction","authors":"Na Jiang, Weiwei Wang, Haoxin Liu, Meiyao Wu, Chunjiang Jia","doi":"10.1016/j.jre.2024.02.015","DOIUrl":"10.1016/j.jre.2024.02.015","url":null,"abstract":"<div><div>The activation of CO<sub>2</sub> molecules is a fundamental step for their effective utilization. Constructing high-density oxygen vacancies on the surface of reducible oxides is pivotal for the activation of CO<sub>2</sub>. In this work, we prepared a series of 0.5Pt<em>x</em>Ce/Al<sub>2</sub>O<sub>3</sub> (<em>x</em>=1, 5, 10, or 20) catalysts with varying Ce loading and 0.5 wt% of Pt for the reverse water gas shift (RWGS) reaction. The size of CeO<sub>2</sub> particle increases with Ce loading. Remarkably, the 0.5Pt5Ce/Al<sub>2</sub>O<sub>3</sub> catalyst with an average CeO<sub>2</sub> particle size of 5.5 nm exhibits a very high CO<sub>2</sub> conversion rate (116.4×10<sup>−5</sup> mol<sub>CO2</sub>/(g<sub>cat</sub>·s)) and CO selectivity (96.1%) at 600 °C. Our experimental findings reveal that the small-size CeO<sub>2</sub> in 0.5Pt5Ce/Al<sub>2</sub>O<sub>3</sub> possesses a greater capacity to generate reactive oxygen vacancies, promoting the adsorption and activation of CO<sub>2</sub>. In addition, the oxygen vacancies are cyclically generated and consumed during the reaction, which contributes to the elevated catalytic performance of the catalyst. This work provides a general strategy to construct rich oxygen vacancies on CeO<sub>2</sub> for designing high-performance catalysts in C<sub>1</sub> chemistry.</div></div>","PeriodicalId":16940,"journal":{"name":"Journal of Rare Earths","volume":"43 2","pages":"Pages 284-294"},"PeriodicalIF":5.2,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140046232","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.2024.03.017
Kai An , Youqiang Wang , Yi Sui , Yongquan Qing , Wei Tong , Xuezhao Wang , Changsheng Liu
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.
{"title":"Recent advances of cerium compounds in functional coatings: Principle, strategies and applications","authors":"Kai An , Youqiang Wang , Yi Sui , Yongquan Qing , Wei Tong , Xuezhao Wang , 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}
Pub Date : 2025-02-01DOI: 10.1016/j.jre.2024.02.018
Xiaorui Wang , Wei Cheng , Ruidong Yang , Jingkun Zang
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 Na2CO3 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 Na2CO3 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.
{"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 , Wei Cheng , Ruidong Yang , 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}
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