Highly active and robust electrocatalysts for methanol oxidation reaction (MOR) are of great significance to the commercial availability of alkaline direct methanol fuel cells (ADMFC). Pd-based nanostructures have received considerable attention in ADMFCs among non-platinum catalysts due to their high activity and tolerance against CO poisoning, which is strongly determined by their composition and structure. Herein, a one-spot hydrothermal method to synthesize Cu-doped Pd7Te3 ultrathin nanowires was proposed. The density functional theory calculations show that the Cu doping simultaneously facilitates the desorption of CO* and adsorption of OH, which refreshes the active sites quickly and thus enhances the electroactivity for MOR. Benefiting from their ultrathin architecture and the modified bonding and anti-bonding d states of Pd, Cu-doped Pd7Te3 nanowires show about twofold and threefold mass activity promotion and enhanced durability for MOR when compared to the pure Pd7Te3 nanowires and commercial Pd/C catalysts. This work not only provides a simple one-step synthesis strategy for Pd-based nanowire catalysts, but also helps to inspire the catalyst design in ADMFC.
Graphical abstract
用于甲醇氧化反应（MOR）的高活性、高稳定性电催化剂对于碱性直接甲醇燃料电池（ADMFC）的商业化具有重要意义。在非铂催化剂中，钯基纳米结构因其高活性和对 CO 中毒的耐受性而在 ADMFC 中受到广泛关注，而这在很大程度上取决于其组成和结构。本文提出了一种单点水热法合成掺铜 Pd7Te3 超细纳米线的方法。密度泛函理论计算表明，Cu 的掺杂同时促进了 CO* 的解吸和 OH 的吸附，从而快速刷新活性位点，增强了 MOR 的电活性。与纯 Pd7Te3 纳米线和商用 Pd/C 催化剂相比，掺铜 Pd7Te3 纳米线得益于其超薄结构以及 Pd 的成键和反成键 d 状态的改变，对 MOR 的质量活性分别提高了两倍和三倍，耐久性也有所增强。这项工作不仅提供了一种简单的一步法合成 Pd 基纳米线催化剂的策略，而且有助于启发 ADMFC 中催化剂的设计。
{"title":"Cu-doped Pd7Te3 nanowires for methanol oxidation under alkaline condition","authors":"Meng-Qian Li, Ze-Qun Han, Jun-Cheng Zhu, Dong-Po He, Qing Hu, Wen-Ya Fan, Qin-Yuan Hu, Xing-Chen Jiao, Qing-Xia Chen","doi":"10.1007/s12598-024-02917-0","DOIUrl":"10.1007/s12598-024-02917-0","url":null,"abstract":"<div><p>Highly active and robust electrocatalysts for methanol oxidation reaction (MOR) are of great significance to the commercial availability of alkaline direct methanol fuel cells (ADMFC). Pd-based nanostructures have received considerable attention in ADMFCs among non-platinum catalysts due to their high activity and tolerance against CO poisoning, which is strongly determined by their composition and structure. Herein, a one-spot hydrothermal method to synthesize Cu-doped Pd<sub>7</sub>Te<sub>3</sub> ultrathin nanowires was proposed. The density functional theory calculations show that the Cu doping simultaneously facilitates the desorption of CO<sup>*</sup> and adsorption of OH, which refreshes the active sites quickly and thus enhances the electroactivity for MOR. Benefiting from their ultrathin architecture and the modified bonding and anti-bonding d states of Pd, Cu-doped Pd<sub>7</sub>Te<sub>3</sub> nanowires show about twofold and threefold mass activity promotion and enhanced durability for MOR when compared to the pure Pd<sub>7</sub>Te<sub>3</sub> nanowires and commercial Pd/C catalysts. This work not only provides a simple one-step synthesis strategy for Pd-based nanowire catalysts, but also helps to inspire the catalyst design in ADMFC.</p><h3>Graphical abstract</h3>\u0000<div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":749,"journal":{"name":"Rare Metals","volume":"44 1","pages":"349 - 357"},"PeriodicalIF":9.6,"publicationDate":"2024-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141863038","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
High-lead solder joints are still playing an indispensable role in military and space applications. Nevertheless, in-depth characterization of high-lead solder joints and the underlying degradation mechanisms remain unexplored. This research first performed aging tests on Sn10Pb90 solder joints, the shear strength at room and elevated temperatures gradually reduced, and the resistance increased. Here, a two-layered Ni–Sn intermetallic compound (IMC) structure was identified using transmission electron microscopy (TEM), which could be attributed to the change of Sn content in the solder. Moreover, the internal annealing twin of a Sn particle was discovered, which could be attributed to creeping induced by thermal expansion coefficient (CTE) difference between Sn and Pb. Detailed analysis of partial and whole annealing twins was conducted through high-resolution TEM (HRTEM). Finally, four degradation mechanisms were proposed. Thickening of the IMC layer would result in increased brittleness and resistivity. For particle coarsening, apart from diminishing the ductility and toughness of the solder joint, it would also accelerate the creeping rate by weakening the phase boundary strength. Regarding voids and cracks induced by phase boundary sliding, wedge-shaped cracking and pore-shaped cracking were discovered and their formation was analyzed. Most importantly, the consumption of Sn resulted in a depletion of wettable layer, leading to the formation of Pb streams and isolated IMC islands, also known as the spalling and delamination of IMCs. Pb diffusion followed a spiral path, which was mutually influenced by orientation misfit and concentration gradient. A technique to prevent cracking was proposed. This research is expected to provide significant technical references for high-lead solder joints.
{"title":"Characterization and degradation of β-Sn particles in thermal aged Pb-rich solder joint for low-temperature co-fired ceramic (LTCC) applications","authors":"Jin-Hong Liu, Zhe Zhu, Qiang-Qiang Nie, Jun-Fu Liu, Peng He, Shu-Ye Zhang","doi":"10.1007/s12598-024-02923-2","DOIUrl":"10.1007/s12598-024-02923-2","url":null,"abstract":"<div><p>High-lead solder joints are still playing an indispensable role in military and space applications. Nevertheless, in-depth characterization of high-lead solder joints and the underlying degradation mechanisms remain unexplored. This research first performed aging tests on Sn10Pb90 solder joints, the shear strength at room and elevated temperatures gradually reduced, and the resistance increased. Here, a two-layered Ni–Sn intermetallic compound (IMC) structure was identified using transmission electron microscopy (TEM), which could be attributed to the change of Sn content in the solder. Moreover, the internal annealing twin of a Sn particle was discovered, which could be attributed to creeping induced by thermal expansion coefficient (CTE) difference between Sn and Pb. Detailed analysis of partial and whole annealing twins was conducted through high-resolution TEM (HRTEM). Finally, four degradation mechanisms were proposed. Thickening of the IMC layer would result in increased brittleness and resistivity. For particle coarsening, apart from diminishing the ductility and toughness of the solder joint, it would also accelerate the creeping rate by weakening the phase boundary strength. Regarding voids and cracks induced by phase boundary sliding, wedge-shaped cracking and pore-shaped cracking were discovered and their formation was analyzed. Most importantly, the consumption of Sn resulted in a depletion of wettable layer, leading to the formation of Pb streams and isolated IMC islands, also known as the spalling and delamination of IMCs. Pb diffusion followed a spiral path, which was mutually influenced by orientation misfit and concentration gradient. A technique to prevent cracking was proposed. This research is expected to provide significant technical references for high-lead solder joints.</p><h3>Graphical abstract</h3>\u0000<div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":749,"journal":{"name":"Rare Metals","volume":"43 10","pages":"5346 - 5361"},"PeriodicalIF":9.6,"publicationDate":"2024-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141872617","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-30DOI: 10.1007/s12598-024-02866-8
Angel J. Garcia-Adeva, Estibaliz Apiñaniz, Aritz Herrero, Ivan R. Aseguinolaza, Alberto Oleaga
The magnetic properties of Ho6MnBi2 and Ho6FeBi2 crystals are investigated by means of density functional theory. These materials are currently an active subject of research in the context of magnetic refrigeration applications since they exhibit a remarkable magnetocaloric effect. In this work, the equation of state, density of states and magnetic moments are calculated and compared with previous experimental results for these materials. Also, the Curie temperatures for the paramagnetic to ferromagnetic phase transition observed in these systems are calculated from first principles. All the calculated quantities are in reasonable agreement with experimental data, which suggests that density functional theory could provide a reliable framework to theoretically investigate the magnetic properties of intermetallic ternary compounds.
{"title":"First-principle calculations of magnetic properties of Ho6(Fe, Mn)Bi2 compounds","authors":"Angel J. Garcia-Adeva, Estibaliz Apiñaniz, Aritz Herrero, Ivan R. Aseguinolaza, Alberto Oleaga","doi":"10.1007/s12598-024-02866-8","DOIUrl":"10.1007/s12598-024-02866-8","url":null,"abstract":"<div><p>The magnetic properties of Ho<sub>6</sub>MnBi<sub>2</sub> and Ho<sub>6</sub>FeBi<sub>2</sub> crystals are investigated by means of density functional theory. These materials are currently an active subject of research in the context of magnetic refrigeration applications since they exhibit a remarkable magnetocaloric effect. In this work, the equation of state, density of states and magnetic moments are calculated and compared with previous experimental results for these materials. Also, the Curie temperatures for the paramagnetic to ferromagnetic phase transition observed in these systems are calculated from first principles. All the calculated quantities are in reasonable agreement with experimental data, which suggests that density functional theory could provide a reliable framework to theoretically investigate the magnetic properties of intermetallic ternary compounds.</p><h3>Graphical abstract</h3><div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":749,"journal":{"name":"Rare Metals","volume":"43 11","pages":"6034 - 6047"},"PeriodicalIF":9.6,"publicationDate":"2024-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s12598-024-02866-8.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141872618","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-29DOI: 10.1007/s12598-024-02929-w
Bing-Rui Liu, Hai-Cheng Zhu, Shao-Hong Liu, Li-Min Zhou, Hao Cui, Man-Men Liu, Li Chen, Ming Wen, Hai-Gang Dong, Feng Liu, Wei Wang, Song Li
Enhancing the ductility of internally oxidized AgMg alloys has posed a longstanding challenge. A new method to achieve simultaneous hardening and toughening of AgMgNi alloys is presented by means of internal oxidation. The influence of Ni content on the internal oxidation process and the mechanical behavior of AgMgNi alloys is systematically investigated. It is found that Ni addition induces grain refinement by forming nanoscale Ni particles, which act as heterogeneous nucleation sites and inhibit grain growth during internal oxidation. This enhances the plasticity and toughness of the alloys via the Hall–Petch effect. The alloys exhibit a conductivity of ~ 42 MS·m−1 and surface hardness of ~ HV 125, which are insensitive to the variation of Ni content within 0 wt%–2 wt%. The optimal range of Ni content for achieving the best combination of hardness, strength and toughness is 0.15 wt%–0.3 wt%, corresponding to alloys with a tensile strength above 300 MPa and a toughness surpassing 3300 MJ·m−3. Higher Ni contents reduce the internal oxidation depth (from about 340.6 to about 238.4 μm) and the tensile strength (from about 342.1 to about 230.1 MPa) of the alloys by generating micrometer-sized Ni-rich particles in the matrix, which consume oxygen, obstruct some of the oxygen diffusion channels and impede the oxidation front advancement. The non-oxidized region, which does not benefit from oxidation strengthening, diminishes the overall strength of the alloy. These results reveal the crucial role of Ni in regulating the internal oxidation dynamics and microstructure evolution of AgMgNi alloys, and suggest a novel approach for designing high-performance alloys with concurrent hardening and toughening.
{"title":"Concurrent toughening and hardening in AgMgNi alloys by internal oxidation","authors":"Bing-Rui Liu, Hai-Cheng Zhu, Shao-Hong Liu, Li-Min Zhou, Hao Cui, Man-Men Liu, Li Chen, Ming Wen, Hai-Gang Dong, Feng Liu, Wei Wang, Song Li","doi":"10.1007/s12598-024-02929-w","DOIUrl":"10.1007/s12598-024-02929-w","url":null,"abstract":"<div><p>Enhancing the ductility of internally oxidized AgMg alloys has posed a longstanding challenge. A new method to achieve simultaneous hardening and toughening of AgMgNi alloys is presented by means of internal oxidation. The influence of Ni content on the internal oxidation process and the mechanical behavior of AgMgNi alloys is systematically investigated. It is found that Ni addition induces grain refinement by forming nanoscale Ni particles, which act as heterogeneous nucleation sites and inhibit grain growth during internal oxidation. This enhances the plasticity and toughness of the alloys via the Hall–Petch effect. The alloys exhibit a conductivity of ~ 42 MS·m<sup>−1</sup> and surface hardness of ~ HV 125, which are insensitive to the variation of Ni content within 0 wt%–2 wt%. The optimal range of Ni content for achieving the best combination of hardness, strength and toughness is 0.15 wt%–0.3 wt%, corresponding to alloys with a tensile strength above 300 MPa and a toughness surpassing 3300 MJ·m<sup>−3</sup>. Higher Ni contents reduce the internal oxidation depth (from about 340.6 to about 238.4 μm) and the tensile strength (from about 342.1 to about 230.1 MPa) of the alloys by generating micrometer-sized Ni-rich particles in the matrix, which consume oxygen, obstruct some of the oxygen diffusion channels and impede the oxidation front advancement. The non-oxidized region, which does not benefit from oxidation strengthening, diminishes the overall strength of the alloy. These results reveal the crucial role of Ni in regulating the internal oxidation dynamics and microstructure evolution of AgMgNi alloys, and suggest a novel approach for designing high-performance alloys with concurrent hardening and toughening.</p><h3>Graphical abstract</h3>\u0000<div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":749,"journal":{"name":"Rare Metals","volume":"43 12","pages":"6625 - 6638"},"PeriodicalIF":9.6,"publicationDate":"2024-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141872662","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
To efficiently diminish the Pt consumption while concurrently enhancing the anodic reaction kinetics, a straightforward synthesis for PtPdAg nanotrees (NTs) with exceedingly low Pt content is presented, utilizing the galvanic replacement reaction between the initially prepared PdAg NTs and Pt ions. Due to the multilevel porous tree-like structure and the incorporation of low amounts of Pt, the electrocatalytic activity and stability of PtPdAg NTs are markedly enhanced, achieving 1.65 and 1.69 A·mg−1Pt + Pd for the anodic reactions of formic acid oxidation (FAOR) and methanol oxidation (MOR) within DLFCs, surpassing the performance of PdAg NTs, as well as that of commercial Pt and Pd black. Density functional theory (DFT) calculations reveal that the addition of low amounts of Pt leads to an increase in the d-band center of PtPdAg NTs and lower the COads adsorption energy to −1.23 eV, enhancing the anti-CO toxicity properties optimally. This approach offers an effective means for designing low Pt catalysts as exceptional anodic electrocatalysts for direct liquid fuel cells.
Graphical abstract
为了在提高阳极反应动力学的同时有效减少铂的消耗，本研究利用最初制备的铂钯银纳米树与铂离子之间的电化学置换反应，提出了一种铂含量极低的铂钯银纳米树（NTs）的直接合成方法。由于铂钯银纳米树具有多级多孔树状结构，且铂的含量较低，因此铂钯银纳米树的电催化活性和稳定性明显增强，在 DLFCs 中的甲酸氧化（FAOR）和甲醇氧化（MOR）阳极反应中，铂钯银纳米树的电催化活性和稳定性分别达到了 1.65 和 1.69 A-mg-1Pt + Pd，超过了铂钯银纳米树以及商用铂黑和钯黑的性能。密度泛函理论（DFT）计算显示，低量铂的添加会导致铂钯银氮氧化物的 d 带中心增大，并将 COads 吸附能降低到 -1.23 eV，从而优化增强了抗 CO 毒性。这种方法为设计低铂催化剂作为直接液体燃料电池的特殊阳极电催化剂提供了有效手段。
{"title":"PtPdAg nanotrees with low Pt content for high CO tolerance within formic acid and methanol electrooxidation","authors":"Yu-Fei Wang, Shou-Lin Zhang, Yu-Xin Deng, Shi-Han Luan, Cai-Kang Wang, Lin-Fei Ding, Xian Jiang, Dong-Mei Sun, Ya-Wen Tang","doi":"10.1007/s12598-024-02921-4","DOIUrl":"10.1007/s12598-024-02921-4","url":null,"abstract":"<div><p>To efficiently diminish the Pt consumption while concurrently enhancing the anodic reaction kinetics, a straightforward synthesis for PtPdAg nanotrees (NTs) with exceedingly low Pt content is presented, utilizing the galvanic replacement reaction between the initially prepared PdAg NTs and Pt ions. Due to the multilevel porous tree-like structure and the incorporation of low amounts of Pt, the electrocatalytic activity and stability of PtPdAg NTs are markedly enhanced, achieving 1.65 and 1.69 A·mg<sup>−1</sup><sub>Pt + Pd</sub> for the anodic reactions of formic acid oxidation (FAOR) and methanol oxidation (MOR) within DLFCs, surpassing the performance of PdAg NTs, as well as that of commercial Pt and Pd black. Density functional theory (DFT) calculations reveal that the addition of low amounts of Pt leads to an increase in the d-band center of PtPdAg NTs and lower the CO<sub>ads</sub> adsorption energy to −1.23 eV, enhancing the anti-CO toxicity properties optimally. This approach offers an effective means for designing low Pt catalysts as exceptional anodic electrocatalysts for direct liquid fuel cells.</p><h3>Graphical abstract</h3>\u0000<div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":749,"journal":{"name":"Rare Metals","volume":"44 1","pages":"300 - 310"},"PeriodicalIF":9.6,"publicationDate":"2024-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141863040","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-27DOI: 10.1007/s12598-024-02908-1
Ming Yang, Tao Luo, Lei Lei, Yun Jiang, Pan-Zhi Wang, Fa-Hong Xu
Uniaxial tensile testing explored the Portevin–Le Chatelier (PLC) effect in nickel-based superalloys featuring high Mo/Cr mass ratios, focusing on the influence of variations in the initial microstructure on the deformation behavior at room and elevated temperatures. Experimental results indicated that the PLC effect was observed solely in the high-temperature tensile curves. However, the deformation mechanisms and characteristics of the PLC effect varied with different initial microstructures. Solid solution (SS) and over-aged (OA) samples exhibited C-type serrations, while under-aged (UA) and peak-aged (PA) specimens, featuring short- and long-range ordered phases, respectively, exhibited A + B type serrations in their tensile curves. Microstructural evolution from the SS to the UA, PA and OA states changed their stacking fault energy (SFE), leading to a sequential transformation in the plastic deformation mechanisms during high-temperature tensile deformation: stacking fault (SF) → nanotwin → microtwin → SF. C-type serrations in the SS samples were associated with high solute-atom contents and SF formation. The PLC effects in the UA and PA samples were predominantly caused by solute atom pinning dislocations. Although precipitates and twins were not the primary drivers of the PLC effect, they impeded dislocation migration, exacerbated solute-atom segregation and enhanced dislocation pinning, generating A + B-shaped serrations. In the OA specimens, precipitated phases induced interfacial mismatch under thermal-force coupling. SF shearing of the precipitated phase and subsequent re-dissolution facilitated the formation of C-type serrations, whose PLC effect was induced by the combined action of dynamic strain aging (DSA), SFs of the matrix and diffusion-controlled pseudo-locking mechanisms.
Graphical abstract
单轴拉伸试验探索了具有高钼/铬质量比的镍基超级合金中的波特文-勒夏特列（PLC）效应，重点研究了初始微观结构的变化对室温和高温下变形行为的影响。实验结果表明，仅在高温拉伸曲线中观察到 PLC 效应。然而，PLC 效应的变形机制和特征随不同的初始微观结构而变化。固溶体（SS）和过老化（OA）试样表现出 C 型锯齿，而欠老化（UA）和峰值老化（PA）试样分别具有短程和长程有序相，其拉伸曲线表现出 A + B 型锯齿。从 SS 到 UA、PA 和 OA 状态的微观结构演变改变了它们的堆积断层能（SFE），导致高温拉伸变形过程中塑性变形机制的顺序转变：堆积断层（SF）→纳米孪晶→微孪晶→SF。SS 样品中的 C 型锯齿与高溶质原子含量和 SF 的形成有关。UA 和 PA 样品中的 PLC 效应主要是由溶质原子钉扎位错引起的。虽然析出物和孪晶不是产生 PLC 效应的主要驱动因素，但它们阻碍了位错迁移，加剧了溶质原子偏析，增强了位错钉扎，从而产生了 A + B 型锯齿。在 OA 试样中，析出相在热力耦合作用下诱发了界面错配。析出相的SF剪切和随后的再溶解促进了C型锯齿的形成，其PLC效应是由动态应变老化（DSA）、基体的SF和扩散控制的伪锁定机制共同作用引起的。
{"title":"Portevin–Le Chatelier (PLC) effect induced by different deformation mechanisms in Ni–25Mo–8Cr alloy during high-temperature tensile deformation","authors":"Ming Yang, Tao Luo, Lei Lei, Yun Jiang, Pan-Zhi Wang, Fa-Hong Xu","doi":"10.1007/s12598-024-02908-1","DOIUrl":"10.1007/s12598-024-02908-1","url":null,"abstract":"<div><p>Uniaxial tensile testing explored the Portevin–Le Chatelier (PLC) effect in nickel-based superalloys featuring high Mo/Cr mass ratios, focusing on the influence of variations in the initial microstructure on the deformation behavior at room and elevated temperatures. Experimental results indicated that the PLC effect was observed solely in the high-temperature tensile curves. However, the deformation mechanisms and characteristics of the PLC effect varied with different initial microstructures. Solid solution (SS) and over-aged (OA) samples exhibited C-type serrations, while under-aged (UA) and peak-aged (PA) specimens, featuring short- and long-range ordered phases, respectively, exhibited A + B type serrations in their tensile curves. Microstructural evolution from the SS to the UA, PA and OA states changed their stacking fault energy (SFE), leading to a sequential transformation in the plastic deformation mechanisms during high-temperature tensile deformation: stacking fault (SF) → nanotwin → microtwin → SF. C-type serrations in the SS samples were associated with high solute-atom contents and SF formation. The PLC effects in the UA and PA samples were predominantly caused by solute atom pinning dislocations. Although precipitates and twins were not the primary drivers of the PLC effect, they impeded dislocation migration, exacerbated solute-atom segregation and enhanced dislocation pinning, generating A + B-shaped serrations. In the OA specimens, precipitated phases induced interfacial mismatch under thermal-force coupling. SF shearing of the precipitated phase and subsequent re-dissolution facilitated the formation of C-type serrations, whose PLC effect was induced by the combined action of dynamic strain aging (DSA), SFs of the matrix and diffusion-controlled pseudo-locking mechanisms.</p><h3>Graphical abstract</h3>\u0000<div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":749,"journal":{"name":"Rare Metals","volume":"44 1","pages":"591 - 607"},"PeriodicalIF":9.6,"publicationDate":"2024-07-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141773774","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-27DOI: 10.1007/s12598-024-02907-2
Xue-Feng Liao, Qing Zhou, Wei-Wei Zeng, Bang Zhou, Hong-Ya Yu, Wei-Da Huang, Wen-Bing Fan, Jia-Sheng Zhang, Zhong-Wu Liu
Nanocrystalline Ce-based rare earth (RE)–Fe–B alloys exhibit relatively good hard magnetic properties and high performance–cost ratio, but their properties deteriorate seriously after hot deformation (HD). Here, we present a simplified one-step HD process for preparing anisotropic Ce-based Ce25.88La2.85Y4.56Fe65.73B0.98 (wt%) magnets. The precursor of nanocrystalline powders is first compacted inside a copper tube, and then the powders with the tube are deformed together to achieve magnetic anisotropy. Compared with the conventional two-step HD magnet, i.e., hot pressing followed by HD, one-step HD significantly increased the coercivity from 1.6 to 3.0 kOe, and the maximum magnetic energy product was improved from 3.7 to 4.8 MGOe. The microstructure characterization indicates that one-step HD can not only produce a more desirable microstructure, characterized by well-aligned platelet-shaped grains with reduced aspect ratio but also greatly inhibit the formation of coarse grain (CG) region. Both of them have been confirmed to be beneficial to enhancing coercivity by micromagnetic simulations. Our results thus demonstrate that the simplified one-step HD process offers a promising approach to developing high-performance anisotropic Ce-based magnets.
Graphical abstract
纳米晶 Ce 基稀土 (RE)-Fe-B 合金具有相对较好的硬磁性能和较高的性能价格比，但其性能在热变形 (HD) 之后会严重恶化。在此，我们提出了一种简化的一步法 HD 工艺，用于制备各向异性的铈基 Ce25.88La2.85Y4.56Fe65.73B0.98 (wt%) 磁体。首先将纳米结晶粉末的前驱体压制在铜管内，然后将粉末与铜管一起变形以实现磁性各向异性。与传统的两步式 HD 磁体（即先热压后 HD）相比，一步式 HD 磁体的矫顽力从 1.6 kOe 显著提高到 3.0 kOe，最大磁能积从 3.7 MGOe 提高到 4.8 MGOe。微观结构表征表明，一步法 HD 不仅能产生更理想的微观结构，即长宽比降低的排列整齐的板状晶粒，还能极大地抑制粗晶粒（CG）区的形成。微磁模拟证实，这两种方法都有利于提高矫顽力。因此，我们的研究结果表明，简化的一步高清工艺为开发高性能各向异性铈基磁体提供了一种可行的方法。
{"title":"Coercivity enhancement of nanocrystalline Ce-based magnets utilizing simplified one-step hot deformation process","authors":"Xue-Feng Liao, Qing Zhou, Wei-Wei Zeng, Bang Zhou, Hong-Ya Yu, Wei-Da Huang, Wen-Bing Fan, Jia-Sheng Zhang, Zhong-Wu Liu","doi":"10.1007/s12598-024-02907-2","DOIUrl":"10.1007/s12598-024-02907-2","url":null,"abstract":"<div><p>Nanocrystalline Ce-based rare earth (RE)–Fe–B alloys exhibit relatively good hard magnetic properties and high performance–cost ratio, but their properties deteriorate seriously after hot deformation (HD). Here, we present a simplified one-step HD process for preparing anisotropic Ce-based Ce<sub>25.88</sub>La<sub>2.85</sub>Y<sub>4.56</sub>Fe<sub>65.73</sub>B<sub>0.98</sub> (wt%) magnets. The precursor of nanocrystalline powders is first compacted inside a copper tube, and then the powders with the tube are deformed together to achieve magnetic anisotropy. Compared with the conventional two-step HD magnet, i.e., hot pressing followed by HD, one-step HD significantly increased the coercivity from 1.6 to 3.0 kOe, and the maximum magnetic energy product was improved from 3.7 to 4.8 MGOe. The microstructure characterization indicates that one-step HD can not only produce a more desirable microstructure, characterized by well-aligned platelet-shaped grains with reduced aspect ratio but also greatly inhibit the formation of coarse grain (CG) region. Both of them have been confirmed to be beneficial to enhancing coercivity by micromagnetic simulations. Our results thus demonstrate that the simplified one-step HD process offers a promising approach to developing high-performance anisotropic Ce-based magnets.</p><h3>Graphical abstract</h3>\u0000<div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":749,"journal":{"name":"Rare Metals","volume":"44 1","pages":"531 - 542"},"PeriodicalIF":9.6,"publicationDate":"2024-07-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141773776","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-27DOI: 10.1007/s12598-024-02894-4
Ke Yan, Yan Zou, Liang-Xue Bao, Qi Xia, Ling-Yi Meng, Hai-Chen Lin, Hui-Xin Chen, Hong-Jun Yue
Lithium/fluorinated carbon (Li/CFx) batteries are greatly limited in their applications mostly due to poor rate performances. In this study, N,P co-doped biomass carbon was synthesized using melamine and phytic acid as doping sources, and the resulting product was then utilized as a precursor for CFx. The resulting fluorinated biomass carbon has a high degree of fluorination, exceeding the specific capacity of commercial fluorinated graphite while also demonstrating exceptional performance at high discharge rates. During the fluorination process, N,P-containing functional groups were removed from the crystalline lattice in the basal plane. This facilitates the formation of a defect-rich carbon matrix, enhancing the F/C ratio by improving the fluorinated active sites and obtaining more highly active semi-ionic bonds. Additionally, the abundant defects and porous structure promote Li+ diffusion. Density functional theory calculations indicated that doping modification effectively reduces the energy barrier for Li+ migration, enhancing Li+ transport efficiency. The prepared CFx delivers material with a maximum specific capacity of 919 mAh·g−1, while maintaining a specific capacity of 702 mAh·g−1 at a high discharge current density of 20C (with a capacity retention rate of 76.4%). In this study, fluorinated N,P co-doped biomass carbon, exhibiting ultrahigh capacity and high-rate performance, was prepared for the first time, which can potentially advance the commercialization of CFx.
{"title":"Fluorinated N,P co-doped biomass carbon with high-rate performance as cathode material for lithium/fluorinated carbon battery","authors":"Ke Yan, Yan Zou, Liang-Xue Bao, Qi Xia, Ling-Yi Meng, Hai-Chen Lin, Hui-Xin Chen, Hong-Jun Yue","doi":"10.1007/s12598-024-02894-4","DOIUrl":"10.1007/s12598-024-02894-4","url":null,"abstract":"<div><p>Lithium/fluorinated carbon (Li/CF<sub><i>x</i></sub>) batteries are greatly limited in their applications mostly due to poor rate performances. In this study, N,P co-doped biomass carbon was synthesized using melamine and phytic acid as doping sources, and the resulting product was then utilized as a precursor for CF<sub><i>x</i></sub>. The resulting fluorinated biomass carbon has a high degree of fluorination, exceeding the specific capacity of commercial fluorinated graphite while also demonstrating exceptional performance at high discharge rates. During the fluorination process, N,P-containing functional groups were removed from the crystalline lattice in the basal plane. This facilitates the formation of a defect-rich carbon matrix, enhancing the F/C ratio by improving the fluorinated active sites and obtaining more highly active semi-ionic bonds. Additionally, the abundant defects and porous structure promote Li<sup>+</sup> diffusion. Density functional theory calculations indicated that doping modification effectively reduces the energy barrier for Li<sup>+</sup> migration, enhancing Li<sup>+</sup> transport efficiency. The prepared CF<sub><i>x</i></sub> delivers material with a maximum specific capacity of 919 mAh·g<sup>−1</sup>, while maintaining a specific capacity of 702 mAh·g<sup>−1</sup> at a high discharge current density of 20C (with a capacity retention rate of 76.4%). In this study, fluorinated N,P co-doped biomass carbon, exhibiting ultrahigh capacity and high-rate performance, was prepared for the first time, which can potentially advance the commercialization of CF<sub><i>x</i></sub>.</p><h3>Graphical abstract</h3>\u0000<div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":749,"journal":{"name":"Rare Metals","volume":"44 1","pages":"110 - 120"},"PeriodicalIF":9.6,"publicationDate":"2024-07-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141773836","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-27DOI: 10.1007/s12598-024-02902-7
Xin-Rui Zheng, Si-Zhe Liang, Zhao-Guo Qiu, Yan-Song Gong, Hong-Xia Meng, Gang Wang, Zhi-Gang Zheng, Wei-Xing Xia, De-Chang Zeng, Ping Liu
Sm–Co-based films play an irreplaceable role in special applications due to their high curie temperature and magnetocrystalline anisotropic energy, especially in heat-assisted magnetic recording (HAMR), but the complex composition of Sm–Co phase and unclear synergistic coupling mechanisms of multi-elemental doping become the challenges to enhance the properties. In this work, a novel strategy combining magnetron sputtering and a high-throughput experiment method is applied to solve the above-mentioned problems. Fe/Cu co-doping highly increases the remanence while maintaining a coercivity larger than 26 kOe, leading to an enhancement of the magnetic energy product to 18.1 MGOe. X-ray diffraction (XRD) and high-resolution transmission electron microscope (HRTEM) reveals that SmCo5 phase occupies the major fraction, with Co atoms partially substituted by Fe and Cu atoms. In situ Lorentz transmission electron microscopy (LTEM) observations show that the Sm (Co, Cu)5 phase effectively prohibits domain wall motions, leading to an increase of coercivity (Hc). Fe doping increases the low saturation magnetization (Ms) and low remanence (Mr) due to the Fe atom having a higher saturation magnetic moment. The magnetization reversal behaviors are further verified by micromagnetic simulations. Our results suggest that Sm–Co-based films prepared via Fe/Cu co-doping could be a promising candidate for high-performed HAMR in the future.
{"title":"Magnetic properties and microstructures of multi-component Sm–Co-based films prepared by high-throughput experiments","authors":"Xin-Rui Zheng, Si-Zhe Liang, Zhao-Guo Qiu, Yan-Song Gong, Hong-Xia Meng, Gang Wang, Zhi-Gang Zheng, Wei-Xing Xia, De-Chang Zeng, Ping Liu","doi":"10.1007/s12598-024-02902-7","DOIUrl":"https://doi.org/10.1007/s12598-024-02902-7","url":null,"abstract":"<p>Sm–Co-based films play an irreplaceable role in special applications due to their high curie temperature and magnetocrystalline anisotropic energy, especially in heat-assisted magnetic recording (HAMR), but the complex composition of Sm–Co phase and unclear synergistic coupling mechanisms of multi-elemental doping become the challenges to enhance the properties. In this work, a novel strategy combining magnetron sputtering and a high-throughput experiment method is applied to solve the above-mentioned problems. Fe/Cu co-doping highly increases the remanence while maintaining a coercivity larger than 26 kOe, leading to an enhancement of the magnetic energy product to 18.1 MGOe. X-ray diffraction (XRD) and high-resolution transmission electron microscope (HRTEM) reveals that SmCo<sub>5</sub> phase occupies the major fraction, with Co atoms partially substituted by Fe and Cu atoms. In situ Lorentz transmission electron microscopy (LTEM) observations show that the Sm (Co, Cu)<sub>5</sub> phase effectively prohibits domain wall motions, leading to an increase of coercivity (<i>H</i><sub>c</sub>). Fe doping increases the low saturation magnetization (<i>M</i><sub>s</sub>) and low remanence (<i>M</i><sub>r</sub>) due to the Fe atom having a higher saturation magnetic moment. The magnetization reversal behaviors are further verified by micromagnetic simulations. Our results suggest that Sm–Co-based films prepared via Fe/Cu co-doping could be a promising candidate for high-performed HAMR in the future.</p><h3 data-test=\"abstract-sub-heading\">Graphical abstract</h3>","PeriodicalId":749,"journal":{"name":"Rare Metals","volume":"69 1","pages":""},"PeriodicalIF":8.8,"publicationDate":"2024-07-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141773775","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-24DOI: 10.1007/s12598-024-02906-3
Zhi-Yuan Song, Yun-Dong Cao, Lin-Lin Fan, Jian Song, Yi Feng, Hong Liu, Cai-Li Lv, Guang-Gang Gao
Constructing a valid heterointerface with a built-in electric field is an effective strategy for designing energy storage anodes with exceptional efficiency for potassium-ion batteries (PIBs) and sodium-ion batteries (SIBs). In this study, WSe2/MoSe2 nanosheets with a better-matched and stable heterojunction interface were uniformly embedded in carbon nanofiber frameworks (WSe2/MoSe2/CNFs). The ion/electron transfer kinetics were facilitated by heterointerfaces with an enlarged effective utilization range. Meanwhile, the heterointerface directed electron transfer from MoSe2 to WSe2 and had significant potassium adsorption capability. The ultra-high pseudocapacitance contribution originating from the heterostructure and morphological features of the WSe2/MoSe2 nanosheets contributed to enhancing high-rate energy storage. Moreover, in situ X-ray diffraction and ex situ X-ray photoelectron spectroscopy revealed the potassification/depotassification behavior of the WSe2/MoSe2/CNFs during the conversion reaction. Consequently, after 500 cycles at 5 A·g−1, the WSe2/MoSe2/CNF anode demonstrated an outstanding long-term cycling performance of 125.6 mAh·g−1 for PIBs. While serving as a SIB electrode, it exhibited an exceptional rate capability of 243.5 mAh·g−1 at 20 A·g−1. With the goal of developing high-performance PIB/SIB electrode materials, the proposed strategy, based on heterointerface adaptation engineering, is promising.
{"title":"WSe2/MoSe2 with a better-matched heterointerface dominating high-performance potassium/sodium storage","authors":"Zhi-Yuan Song, Yun-Dong Cao, Lin-Lin Fan, Jian Song, Yi Feng, Hong Liu, Cai-Li Lv, Guang-Gang Gao","doi":"10.1007/s12598-024-02906-3","DOIUrl":"10.1007/s12598-024-02906-3","url":null,"abstract":"<div><p>Constructing a valid heterointerface with a built-in electric field is an effective strategy for designing energy storage anodes with exceptional efficiency for potassium-ion batteries (PIBs) and sodium-ion batteries (SIBs). In this study, WSe<sub>2</sub>/MoSe<sub>2</sub> nanosheets with a better-matched and stable heterojunction interface were uniformly embedded in carbon nanofiber frameworks (WSe<sub>2</sub>/MoSe<sub>2</sub>/CNFs). The ion/electron transfer kinetics were facilitated by heterointerfaces with an enlarged effective utilization range. Meanwhile, the heterointerface directed electron transfer from MoSe<sub>2</sub> to WSe<sub>2</sub> and had significant potassium adsorption capability. The ultra-high pseudocapacitance contribution originating from the heterostructure and morphological features of the WSe<sub>2</sub>/MoSe<sub>2</sub> nanosheets contributed to enhancing high-rate energy storage. Moreover, in situ X-ray diffraction and ex situ X-ray photoelectron spectroscopy revealed the potassification/depotassification behavior of the WSe<sub>2</sub>/MoSe<sub>2</sub>/CNFs during the conversion reaction. Consequently, after 500 cycles at 5 A·g<sup>−1</sup>, the WSe<sub>2</sub>/MoSe<sub>2</sub>/CNF anode demonstrated an outstanding long-term cycling performance of 125.6 mAh·g<sup>−1</sup> for PIBs. While serving as a SIB electrode, it exhibited an exceptional rate capability of 243.5 mAh·g<sup>−1</sup> at 20 A·g<sup>−1</sup>. With the goal of developing high-performance PIB/SIB electrode materials, the proposed strategy, based on heterointerface adaptation engineering, is promising.</p><h3>Graphical abstract</h3><div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":749,"journal":{"name":"Rare Metals","volume":"44 1","pages":"195 - 208"},"PeriodicalIF":9.6,"publicationDate":"2024-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141773777","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
扫码关注我们
求助内容：
应助结果提醒方式：
京公网安备 11010802042870号