Materials Today Physics最新文献_第5页

Large magnetocaloric effect near liquid hydrogen temperatures in Er1-xTmxGa materials Er1-xTmxGa 材料在液氢温度附近的大磁致效应

IF 1 2区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Materials Today Physics

Pub Date : 2025-01-01 DOI: 10.1016/j.mtphys.2024.101609

Dingsong Wang , Xinqi Zheng , Lunhua He , Hui Wu , Yawei Gao , Guyue Wang , Hao Liu , Shanshan Zhen , Yang Pan , Zixiao Zhang , Guangrui Zhang , Anxu Ma , Zhe Chen , Lei Xi , Jiawang Xu , Shouguo Wang , Baogen Shen

Low-temperature magnetocaloric materials are of great importance for potential applications of gas liquefaction such as nitrogen, hydrogen and helium for their low liquidation temperatures (∼4 K for helium, ∼20 K for hydrogen and ∼77 K for nitrogen respectively), of which the working temperature, the maximal magnetic entropy change ((-ΔS_M)_max), the maximal adiabatic temperature change ((ΔT_ad)_max), and the temperature average entropy change (TEC) are the key assessment parameters. Herein, we designed and synthesized Er_1-xTm_xGa series compounds based on the optimization of the spin quantum number (Spin) with their magnetic ordering temperature successfully adjusted from 31.0 K to 15.0 K, which covers the liquid hydrogen temperature range. Particularly, Er_0.8Tm_0.2Ga shows outstanding (-ΔS_M)_max, TEC(20), and (ΔT_ad)_max values of 13.6 J/kg K, 10.1 J/kg K, and 4.3 K under the field change of 0–2 T, respectively, which are increased by 32.0 %, 36.4 %, and 48.2 % compared with the parent ErGa compound. It should be noted that the refrigerant capacity (RC) of Er_0.8Tm_0.2Ga is not only larger than ErGa but also larger than TmGa. Furthermore, neutron powder diffraction (NPD) was employed on Er_0.8Tm_0.2Ga to reveal the physical mechanism of its enhanced magnetocaloric effect (MCE). It is found that for Er_0.8Tm_0.2Ga the more pronounced order-to-disorder transition than the spin reorientation (SR) transition, the characteristic second order phase transition, and the existence of the short-range magnetic ordering above the magnetic ordering temperature should be jointly responsible for its large magnetocaloric effect.

低温磁致伸缩材料对氮气、氢气和氦气等气体液化的潜在应用非常重要，因为它们的液化温度低（氦气为 4 K，氢气为 20 K，氮气为 77 K）、其中工作温度、最大磁熵变（(-ΔSM)max）、最大绝热温度变化（(ΔTad)max）和温度平均熵变（TEC）是关键的评估参数。在此，我们在优化自旋量子数（Spin）的基础上设计并合成了 Er1-xTmxGa 系列化合物，并成功地将其磁有序温度从 31.0 K 调整到 15.0 K，涵盖了液氢温度范围。尤其是 Er0.8Tm0.2Ga，在 0-2 T 的磁场变化下，其 (-ΔSM)max 值、TEC(20) 值和 (ΔTad)max 值分别达到 13.6 J/kg K、10.1 J/kg K 和 4.3 K，与母体 ErGa 化合物相比，分别提高了 32.0 %、36.4 % 和 48.2 %。值得注意的是，Er0.8Tm0.2Ga 的制冷剂容量（RC）不仅大于 ErGa，也大于 TmGa。此外，还对 Er0.8Tm0.2Ga 进行了中子粉末衍射（NPD），以揭示其增强磁致效应（MCE）的物理机制。研究发现，对于 Er0.8Tm0.2Ga，比自旋重新定向（SR）转变更明显的有序到无序转变、特征性的二阶相变以及高于磁有序温度的短程磁有序的存在应该是其巨大磁ocaloric效应的共同原因。

{"title":"Large magnetocaloric effect near liquid hydrogen temperatures in Er1-xTmxGa materials","authors":"Dingsong Wang , Xinqi Zheng , Lunhua He , Hui Wu , Yawei Gao , Guyue Wang , Hao Liu , Shanshan Zhen , Yang Pan , Zixiao Zhang , Guangrui Zhang , Anxu Ma , Zhe Chen , Lei Xi , Jiawang Xu , Shouguo Wang , Baogen Shen","doi":"10.1016/j.mtphys.2024.101609","DOIUrl":"10.1016/j.mtphys.2024.101609","url":null,"abstract":"<div><div>Low-temperature magnetocaloric materials are of great importance for potential applications of gas liquefaction such as nitrogen, hydrogen and helium for their low liquidation temperatures (∼4 K for helium, ∼20 K for hydrogen and ∼77 K for nitrogen respectively), of which the working temperature, the maximal magnetic entropy change (<em>(-ΔS</em><sub><em>M</em></sub><em>)</em><sub><em>max</em></sub>), the maximal adiabatic temperature change (<em>(ΔT</em><sub><em>ad</em></sub><em>)</em><sub><em>max</em></sub>), and the temperature average entropy change (<em>TEC</em>) are the key assessment parameters. Herein, we designed and synthesized Er<sub>1-x</sub>Tm<sub>x</sub>Ga series compounds based on the optimization of the spin quantum number (<em>Spin</em>) with their magnetic ordering temperature successfully adjusted from 31.0 K to 15.0 K, which covers the liquid hydrogen temperature range. Particularly, Er<sub>0.8</sub>Tm<sub>0.2</sub>Ga shows outstanding (-ΔS<sub>M</sub>)<sub>max</sub>, <em>TEC</em>(20), and <em>(ΔT</em><sub><em>ad</em></sub><em>)</em><sub><em>max</em></sub> values of 13.6 J/kg K, 10.1 J/kg K, and 4.3 K under the field change of 0–2 T, respectively, which are increased by 32.0 %, 36.4 %, and 48.2 % compared with the parent ErGa compound. It should be noted that the refrigerant capacity (RC) of Er<sub>0.8</sub>Tm<sub>0.2</sub>Ga is not only larger than ErGa but also larger than TmGa. Furthermore, neutron powder diffraction (NPD) was employed on Er<sub>0.8</sub>Tm<sub>0.2</sub>Ga to reveal the physical mechanism of its enhanced magnetocaloric effect (MCE). It is found that for Er<sub>0.8</sub>Tm<sub>0.2</sub>Ga the more pronounced order-to-disorder transition than the spin reorientation (SR) transition, the characteristic second order phase transition, and the existence of the short-range magnetic ordering above the magnetic ordering temperature should be jointly responsible for its large magnetocaloric effect.</div></div>","PeriodicalId":18253,"journal":{"name":"Materials Today Physics","volume":"50 ","pages":"Article 101609"},"PeriodicalIF":10.0,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142735518","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Rare earth stannates: A new high-performance wave-transparent material investigated through theoretical and experimental approaches 稀土锡酸盐：通过理论和实验方法研究一种新型高性能透波材料

IF 1 2区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Materials Today Physics

Pub Date : 2025-01-01 DOI: 10.1016/j.mtphys.2024.101622

Shuping Wen, Zhilin Chen, Zhilin Tian, Liya Zheng, Bin Li

Wave-transparent materials are widely used as integrated structural-functional materials in various aircraft communication systems. However, the lack of high-performance wave-transparent materials has impeded the advancement of hypersonic aircraft. Consequently, the search for novel high-performance wave-transparent materials has become a critical challenge. This study investigates the dielectric, mechanical, and thermal properties of RE₂Sn₂O₇ (RE = La, Nd, Sm, Eu, Gd, Tb, Dy, Er, and Lu) using both theoretical predictions and experimental measurements to evaluate their suitability as wave-transparent materials. Preliminary first-principles calculations predict exceptional mechanical properties for RE₂Sn₂O₇. These predictions are confirmed experimentally, with synthesized RE₂Sn₂O₇ samples exhibiting Young's modulus exceeding 200 GPa and hardness greater than 10 GPa. Additionally, they also present low dielectric constants (∼8) and dielectric loss tangent values below 0.01 with the dielectric constant unaffected by RE species, while the dielectric loss tangent value decreases as the RE³⁺ ionic radius decreases. Their thermal expansion coefficients range between of 8 × 10⁻⁶ K⁻¹ and 10 × 10⁻⁶ K⁻¹, while thermal conductivities can be as low as 2 W m⁻¹ K⁻¹. The relationship between RE³⁺ ionic radius and intrinsic properties is elucidated, revealing that a smaller ionic radius reduces dielectric loss tangent value while enhancing Young's modulus, hardness, and thermal expansion coefficient. These results provide valuable theoretical guidance for design of high-performance wave-transparent materials.

波透明材料作为一种集结构功能于一体的材料广泛应用于各种飞机通信系统中。然而，高性能透明波材料的缺乏阻碍了高超声速飞机的发展。因此，寻找新的高性能波透明材料已成为一个关键的挑战。本研究研究了RE2Sn2O7 （RE = La, Nd, Sm, Eu, Gd, Tb, Dy， Er和Lu）的介电，力学和热性能，采用理论预测和实验测量来评估其作为波透明材料的适用性。初步的第一性原理计算预测了RE₂Sn₂O₇的特殊机械性能。这些预测得到了实验的证实，合成的RE₂Sn₂O₇样品的杨氏模量超过200 GPa，硬度大于10 GPa。此外，它们还表现出低介电常数（~ 8）和介电损耗正切值低于0.01，介电常数不受RE种类的影响，而介电损耗正切值随着RE³离子半径的减小而减小。它们的热膨胀系数在8 × 10−6 K−1到10 × 10−6 K−1之间，导热系数可低至2w·m·K⁻1。研究了RE³+离子半径与材料本征性质之间的关系，表明离子半径越小，介电损耗正切值越小，杨氏模量、硬度和热膨胀系数也越高。这些结果为高性能波透明材料的设计提供了有价值的理论指导。

{"title":"Rare earth stannates: A new high-performance wave-transparent material investigated through theoretical and experimental approaches","authors":"Shuping Wen, Zhilin Chen, Zhilin Tian, Liya Zheng, Bin Li","doi":"10.1016/j.mtphys.2024.101622","DOIUrl":"10.1016/j.mtphys.2024.101622","url":null,"abstract":"<div><div>Wave-transparent materials are widely used as integrated structural-functional materials in various aircraft communication systems. However, the lack of high-performance wave-transparent materials has impeded the advancement of hypersonic aircraft. Consequently, the search for novel high-performance wave-transparent materials has become a critical challenge. This study investigates the dielectric, mechanical, and thermal properties of RE<sub>2</sub>Sn<sub>2</sub>O<sub>7</sub> (RE = La, Nd, Sm, Eu, Gd, Tb, Dy, Er, and Lu) using both theoretical predictions and experimental measurements to evaluate their suitability as wave-transparent materials. Preliminary first-principles calculations predict exceptional mechanical properties for RE₂Sn₂O₇. These predictions are confirmed experimentally, with synthesized RE₂Sn₂O₇ samples exhibiting Young's modulus exceeding 200 GPa and hardness greater than 10 GPa. Additionally, they also present low dielectric constants (∼8) and dielectric loss tangent values below 0.01 with the dielectric constant unaffected by RE species, while the dielectric loss tangent value decreases as the RE³⁺ ionic radius decreases. Their thermal expansion coefficients range between of 8 × 10<sup>−6</sup> K<sup>−1</sup> and 10 × 10<sup>−6</sup> K<sup>−1</sup>, while thermal conductivities can be as low as 2 W m⁻<sup>1</sup> K⁻<sup>1</sup>. The relationship between RE³⁺ ionic radius and intrinsic properties is elucidated, revealing that a smaller ionic radius reduces dielectric loss tangent value while enhancing Young's modulus, hardness, and thermal expansion coefficient. These results provide valuable theoretical guidance for design of high-performance wave-transparent materials.</div></div>","PeriodicalId":18253,"journal":{"name":"Materials Today Physics","volume":"50 ","pages":"Article 101622"},"PeriodicalIF":10.0,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142797752","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Hetero-structured construction of RGO nanosheets decorated by flower-like MoS2 toward the regulation of electromagnetic wave absorption performance 花状二硫化钼修饰氧化石墨烯纳米片的异质结构构建对电磁波吸收性能的调控

IF 1 2区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Materials Today Physics

Pub Date : 2025-01-01 DOI: 10.1016/j.mtphys.2024.101631

Zhengzheng Guo , Ze Zong , Yanyan Cao , Yidan Zhao , Fuqiang Wang , Peien Luo , Shanhui Liu , Fang Ren , Penggang Ren

Exploring high-efficiency graphene-based electromagnetic wave (EMW) absorption materials is urgently required owing to the increasingly severe electromagnetic radiation pollution. However, the serious impedance mismatching caused by the superior conductivity of graphene and finite attenuation mechanism constrain its development. Herein, MoS₂@RGO with plentiful heterointerfaces are fabricated by a facile solvothermal strategy to realize outstanding EMW absorption. The incorporation of MoS₂ could not only effectively reduce the conductivity of RGO to alleviate the impedance mismatching issue, but also greatly enrich the loss mechanisms. In addition, the construction of flower-like MoS₂ assembled by MoS₂ could greatly prolong the transmission path of EMW through multiple reflection and scattering. The improved impedance matching and multiple dissipation mechanisms jointly endow the developed materials with brilliant EMW absorption performance. The prepared MoS₂@RGO with a 1:1 ratio of MoS₂ to RGO (MR3) at a low filler loading of 20 wt% achieves the minimum reflection loss of −69.6 dB at the frequency of 8.46 GHz under a low thickness of 2.77 mm and a broad effective absorption bandwidth of 4.36 GHz (from 11.00 to 15.36 GHz). Notably, the effectiveness of the resultant MR composites used as actual absorbers is strongly verified by the radar cross section simulation. This work opens up new possibilities for constructing hetero-structured graphene-based composites with rich heterointerfaces toward excellent electromagnetic protection.

随着电磁辐射污染的日益严重，迫切需要开发高效石墨烯基电磁波吸收材料。然而，石墨烯优异的导电性和有限的衰减机制导致的严重阻抗失配限制了其发展。本文采用简单的溶剂热策略制备了具有丰富异质界面的MoS2@RGO，以实现出色的EMW吸收。MoS2的掺入不仅可以有效降低RGO的电导率，缓解阻抗失配问题，还可以极大地丰富其损耗机制。此外，由二硫化钼组装而成的花状二硫化钼结构可以大大延长EMW通过多次反射和散射的传输路径。改进的阻抗匹配和多种耗散机制使所开发的材料具有优异的EMW吸收性能。在所制备的MoS2@RGO材料中，MoS2与RGO （MR3）的比例为1:1，填充量为20wt %，在8.46 GHz频率下，厚度为2.77 mm，反射损耗最小，为-69.6 dB，有效吸收带宽为4.36 GHz （11.00 ~ 15.36 GHz）。值得注意的是，合成的MR复合材料作为实际吸收剂的有效性通过雷达截面模拟得到了有力的验证。这项工作为构建具有丰富异质界面的异质结构石墨烯基复合材料提供了新的可能性，从而实现出色的电磁保护。

{"title":"Hetero-structured construction of RGO nanosheets decorated by flower-like MoS2 toward the regulation of electromagnetic wave absorption performance","authors":"Zhengzheng Guo , Ze Zong , Yanyan Cao , Yidan Zhao , Fuqiang Wang , Peien Luo , Shanhui Liu , Fang Ren , Penggang Ren","doi":"10.1016/j.mtphys.2024.101631","DOIUrl":"10.1016/j.mtphys.2024.101631","url":null,"abstract":"<div><div>Exploring high-efficiency graphene-based electromagnetic wave (EMW) absorption materials is urgently required owing to the increasingly severe electromagnetic radiation pollution. However, the serious impedance mismatching caused by the superior conductivity of graphene and finite attenuation mechanism constrain its development. Herein, MoS<sub>2</sub>@RGO with plentiful heterointerfaces are fabricated by a facile solvothermal strategy to realize outstanding EMW absorption. The incorporation of MoS<sub>2</sub> could not only effectively reduce the conductivity of RGO to alleviate the impedance mismatching issue, but also greatly enrich the loss mechanisms. In addition, the construction of flower-like MoS<sub>2</sub> assembled by MoS<sub>2</sub> could greatly prolong the transmission path of EMW through multiple reflection and scattering. The improved impedance matching and multiple dissipation mechanisms jointly endow the developed materials with brilliant EMW absorption performance. The prepared MoS<sub>2</sub>@RGO with a 1:1 ratio of MoS<sub>2</sub> to RGO (MR3) at a low filler loading of 20 wt% achieves the minimum reflection loss of −69.6 dB at the frequency of 8.46 GHz under a low thickness of 2.77 mm and a broad effective absorption bandwidth of 4.36 GHz (from 11.00 to 15.36 GHz). Notably, the effectiveness of the resultant MR composites used as actual absorbers is strongly verified by the radar cross section simulation. This work opens up new possibilities for constructing hetero-structured graphene-based composites with rich heterointerfaces toward excellent electromagnetic protection.</div></div>","PeriodicalId":18253,"journal":{"name":"Materials Today Physics","volume":"50 ","pages":"Article 101631"},"PeriodicalIF":10.0,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142849493","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Heteroatom-doping effects on high-temperature infrared emission of (LaPr)2Ce2O7 ceramics 杂原子掺杂对（LaPr）2Ce2O7陶瓷高温红外发射的影响

IF 1 2区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Materials Today Physics

Pub Date : 2025-01-01 DOI: 10.1016/j.mtphys.2024.101615

Guang-Yang Xin , Xieeryazidan Aday , Cheng-Yu He , Bao-Hua Liu , Guo-Yu Ren , Hui-Xia Guo , Xiang-Hu Gao

Manipulating thermal radiation through electromagnetic waves while maximizing heat transfer efficiency is critical for energy conservation and thermal protection in high-temperature environments. In this study, a series of heteroatom-doped (LaPr)₂Ce₂O₇ ceramics are synthesized, with a defect fluorite structure, exhibiting differential infrared radiation properties over a broad spectrum. In particular, doping with low-valence transition metals (Cu and Co) introduces impurity levels and oxygen vacancies, effectively reducing the intrinsic bandgap and increasing emissivity at wavelengths below 6 μm. Meanwhile, the mismatched properties in mass and ionic radius between the dopants and host atoms increase the asymmetry of the lattice structure, which is beneficial for long-wavelength emissivity (>6 μm). The infrared emissivity of (LaPrCu)₂Ce₂O₇ reaches 0.870 across a broad wavelength range from 0.78 μm to 16 μm, surpassing that of pristine (LaPr)₂Ce₂O₇. This enhancement is attributed to the effective collaboration of impurity absorption, free carrier absorption, and lattice absorption. More importantly, the achieved near black-body thermal emissivity at 1300 °C is suitable for applications in high-temperature thermal radiation. In contrast, the introduction of rare-earth elements (Gd and Ho) has a small impact on infrared emissivity due to their similar characteristics to La³⁺ and Pr³⁺. Our findings provide a valuable reference for achieving high-performance infrared emission in rare-earth cerates through doping engineering.

通过电磁波控制热辐射，同时最大限度地提高热传导效率是在高温环境中节能和热防护的关键。在本研究中，合成了一系列杂原子掺杂（LaPr）2Ce2O7陶瓷，具有缺陷萤石结构，在广谱上表现出不同的红外辐射特性。特别是，掺杂了低价过渡金属（Cu和Co），引入了杂质水平和氧空位，有效地减小了本征带隙，提高了6 μm以下波长的发射率。同时，掺杂剂与主原子在质量和离子半径上的不匹配特性增加了晶格结构的不对称性，这有利于长波发射率(>；6μm)。在0.78 ~ 16 μm波长范围内，（LaPrCu）2Ce2O7的红外发射率达到0.870，超过了原始（LaPr）2Ce2O7。这种增强归因于杂质吸收、自由载流子吸收和晶格吸收的有效协同作用。更重要的是，在1300℃下获得的近黑体热辐射率适合应用于高温热辐射。相反，稀土元素（Gd和Ho）的引入对红外发射率的影响较小，因为它们与La3+和Pr3+的特性相似。本研究结果为通过掺杂工程实现稀土酸盐的高性能红外发射提供了有价值的参考。

{"title":"Heteroatom-doping effects on high-temperature infrared emission of (LaPr)2Ce2O7 ceramics","authors":"Guang-Yang Xin , Xieeryazidan Aday , Cheng-Yu He , Bao-Hua Liu , Guo-Yu Ren , Hui-Xia Guo , Xiang-Hu Gao","doi":"10.1016/j.mtphys.2024.101615","DOIUrl":"10.1016/j.mtphys.2024.101615","url":null,"abstract":"<div><div>Manipulating thermal radiation through electromagnetic waves while maximizing heat transfer efficiency is critical for energy conservation and thermal protection in high-temperature environments. In this study, a series of heteroatom-doped (LaPr)<sub>2</sub>Ce<sub>2</sub>O<sub>7</sub> ceramics are synthesized, with a defect fluorite structure, exhibiting differential infrared radiation properties over a broad spectrum. In particular, doping with low-valence transition metals (Cu and Co) introduces impurity levels and oxygen vacancies, effectively reducing the intrinsic bandgap and increasing emissivity at wavelengths below 6 μm. Meanwhile, the mismatched properties in mass and ionic radius between the dopants and host atoms increase the asymmetry of the lattice structure, which is beneficial for long-wavelength emissivity (>6 μm). The infrared emissivity of (LaPrCu)<sub>2</sub>Ce<sub>2</sub>O<sub>7</sub> reaches 0.870 across a broad wavelength range from 0.78 μm to 16 μm, surpassing that of pristine (LaPr)<sub>2</sub>Ce<sub>2</sub>O<sub>7</sub>. This enhancement is attributed to the effective collaboration of impurity absorption, free carrier absorption, and lattice absorption. More importantly, the achieved near black-body thermal emissivity at 1300 °C is suitable for applications in high-temperature thermal radiation. In contrast, the introduction of rare-earth elements (Gd and Ho) has a small impact on infrared emissivity due to their similar characteristics to La<sup>3+</sup> and Pr<sup>3+</sup>. Our findings provide a valuable reference for achieving high-performance infrared emission in rare-earth cerates through doping engineering.</div></div>","PeriodicalId":18253,"journal":{"name":"Materials Today Physics","volume":"50 ","pages":"Article 101615"},"PeriodicalIF":10.0,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142782495","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Computational investigation of NaKFePO4F fluorophosphate as a high-performance cathode material for Na/K-ion batteries Na/ k离子电池高性能正极材料NaKFePO4F的计算研究

IF 1 2区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Materials Today Physics

Pub Date : 2025-01-01 DOI: 10.1016/j.mtphys.2024.101623

Abdelghani Bensassi , Zineb El Kacemi , Zouhir Mansouri , Abdelfattah Mahmoud , Mohamed Balli , Abdallah El Kenz , Abdelilah Benyoussef , Omar Mounkachi

Recently, NaKFePO₄F, a layered iron-based fluorophosphate, has been proposed as a promising cathode material for both sodium-ion (SIBs) and potassium-ion batteries (KIBs), with an ion-exchange strategy significantly enhancing its capacity and addressing its low electronic conductivity. However, the atomic-scale mechanisms driving these improvements have yet to be fully explained. For this reason, density functional theory (DFT) and ab initio molecular dynamics (AIMD) simulations were systematically employed to assess the electrochemical feasibility of NaKFePO₄F as a novel cathode material for these batteries. Analysis of energetically stable configurations reveals that a 50 % exchange of Na with K stabilizes and activates the previously inert sites in the pristine Na₂FePO₄F material. Notably, NaKFePO₄F exhibits enhanced thermodynamic stability and electronic conductivity, with a reduced band gap of 2.40 eV compared to 3.18 eV in the pristine material. Moreover, NaKFePO₄F was found to exhibit a low activation energy barrier of 0.42 eV for K ions, as determined by climbing image nudged elastic band (CI-NEB) computations. AIMD predictions also indicate that this material can sustain elevated temperatures from 300 K to 800 K, with ion diffusivity described accordingly. Ultimately, NaKFePO₄F achieved an average discharge voltage of 3.67 V and an energy density of 426 Wh/kg for KIBs, surpassing the 3.49 V discharge voltage and 405 Wh/kg energy density of SIBs. Given these predicted results, NaKFePO₄F is expected to be a promising cathode material for post-lithium-ion battery technology.

最近，一种层状铁基氟磷酸盐NaKFePO4F被提出作为钠离子（SIBs）和钾离子电池（KIBs）的有前途的正极材料，离子交换策略显着提高了其容量并解决了其低电子导电性。然而，推动这些改进的原子尺度机制尚未得到充分解释。为此，系统地采用密度泛函理论（DFT）和从头算分子动力学（AIMD）模拟来评估NaKFePO4F作为新型电池正极材料的电化学可行性。对能量稳定构型的分析表明，50%的Na与K交换稳定并激活了原始Na2FePO4F材料中先前的惰性位点。值得注意的是，NaKFePO4F表现出增强的热力学稳定性和电子导电性，与原始材料的3.18 eV相比，带隙减少了2.40 eV。此外，通过爬升图像推动弹性带（CI-NEB）计算，发现NaKFePO4F对K离子具有0.42 eV的低活化能垒。AIMD的预测还表明，这种材料可以承受从300 K到800 K的高温，并相应地描述了离子扩散率。最终，NaKFePO4F实现了kib的平均放电电压为3.67 V，能量密度为426 Wh/kg，超过了sib的3.49 V放电电压和405 Wh/kg能量密度。鉴于这些预测结果，NaKFePO4F有望成为后锂离子电池技术的一种有前途的正极材料。

{"title":"Computational investigation of NaKFePO4F fluorophosphate as a high-performance cathode material for Na/K-ion batteries","authors":"Abdelghani Bensassi , Zineb El Kacemi , Zouhir Mansouri , Abdelfattah Mahmoud , Mohamed Balli , Abdallah El Kenz , Abdelilah Benyoussef , Omar Mounkachi","doi":"10.1016/j.mtphys.2024.101623","DOIUrl":"10.1016/j.mtphys.2024.101623","url":null,"abstract":"<div><div>Recently, NaKFePO<sub>4</sub>F, a layered iron-based fluorophosphate, has been proposed as a promising cathode material for both sodium-ion (SIBs) and potassium-ion batteries (KIBs), with an ion-exchange strategy significantly enhancing its capacity and addressing its low electronic conductivity. However, the atomic-scale mechanisms driving these improvements have yet to be fully explained. For this reason, density functional theory (DFT) and ab initio molecular dynamics (AIMD) simulations were systematically employed to assess the electrochemical feasibility of NaKFePO<sub>4</sub>F as a novel cathode material for these batteries. Analysis of energetically stable configurations reveals that a 50 % exchange of Na with K stabilizes and activates the previously inert sites in the pristine Na<sub>2</sub>FePO<sub>4</sub>F material. Notably, NaKFePO<sub>4</sub>F exhibits enhanced thermodynamic stability and electronic conductivity, with a reduced band gap of 2.40 eV compared to 3.18 eV in the pristine material. Moreover, NaKFePO<sub>4</sub>F was found to exhibit a low activation energy barrier of 0.42 eV for K ions, as determined by climbing image nudged elastic band (CI-NEB) computations. AIMD predictions also indicate that this material can sustain elevated temperatures from 300 K to 800 K, with ion diffusivity described accordingly. Ultimately, NaKFePO<sub>4</sub>F achieved an average discharge voltage of 3.67 V and an energy density of 426 Wh/kg for KIBs, surpassing the 3.49 V discharge voltage and 405 Wh/kg energy density of SIBs. Given these predicted results, NaKFePO<sub>4</sub>F is expected to be a promising cathode material for post-lithium-ion battery technology.</div></div>","PeriodicalId":18253,"journal":{"name":"Materials Today Physics","volume":"50 ","pages":"Article 101623"},"PeriodicalIF":10.0,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142804676","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Rapid prediction of phonon density of states by crystal attention graph neural network and high-throughput screening of candidate substrates for wide bandgap electronic cooling 晶体注意图神经网络快速预测声子态密度及宽带隙电子冷却候选衬底的高通量筛选

IF 1 2区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Materials Today Physics

Pub Date : 2025-01-01 DOI: 10.1016/j.mtphys.2024.101632

Mohammed Al-Fahdi , Changpeng Lin , Chen Shen , Hongbin Zhang , Ming Hu

Machine learning has demonstrated superior performance in predicting vast materials properties. However, predicting a spectral-like continuous material property such as phonon density of states (DOS) is more challenging for machine learning. In this work, with phonon DOS of 4994 inorganic structures with 62 unique elements calculated by density functional theory (DFT), we developed a crystal attention graph neural network (CATGNN) model for predicting total phonon DOS of crystalline materials. The computational cost of training the CATGNN model is several orders of magnitude cheaper than full DFT calculations. We find that high vibrational similarity or phonon DOS overlap is not the only requirement to obtain high interfacial thermal conductance (ITC) instead, the average acoustic group velocity of heat source and heat sink for the acoustic branches in the phonon DOS overlap region is equally important in determining ITC. Pearson correlation analysis yields a few simple material descriptors that are strongly but negatively correlated with ITC. These easy-to-calculate material features combined with the proposed high average acoustic group velocity and phonon DOS overlap predicted by CATGNN model offer a new reliable and fast route for high-throughput screening of novel crystalline materials with desirable high ITC for phonon-mediated thermal management of wide bandgap electronics.

机器学习在预测大量材料特性方面表现出了卓越的性能。然而，预测类似光谱的连续材料特性，如声子态密度（DOS），对于机器学习来说更具挑战性。本文利用密度泛函理论（DFT）计算了4,994种具有62种独特元素的无机结构的声子DOS，建立了晶体注意图神经网络（CATGNN）模型，用于预测晶体材料的总声子DOS。训练CATGNN模型的计算成本比全DFT计算便宜几个数量级。研究发现，高振动相似度或声子DOS重叠并不是获得高界面热导（ITC）的唯一条件，声子DOS重叠区内声子分支的热源和散热器的平均声群速度对于确定ITC同样重要。皮尔逊相关分析产生了一些简单的材料描述符，它们与ITC强烈但负相关。这些易于计算的材料特征与CATGNN模型预测的高平均声群速度和声子DOS重叠相结合，为高通量筛选具有理想高ITC的新型晶体材料提供了一种新的可靠和快速的途径，用于宽带隙电子声子介导的热管理。

{"title":"Rapid prediction of phonon density of states by crystal attention graph neural network and high-throughput screening of candidate substrates for wide bandgap electronic cooling","authors":"Mohammed Al-Fahdi , Changpeng Lin , Chen Shen , Hongbin Zhang , Ming Hu","doi":"10.1016/j.mtphys.2024.101632","DOIUrl":"10.1016/j.mtphys.2024.101632","url":null,"abstract":"<div><div>Machine learning has demonstrated superior performance in predicting vast materials properties. However, predicting a spectral-like continuous material property such as phonon density of states (DOS) is more challenging for machine learning. In this work, with phonon DOS of 4994 inorganic structures with 62 unique elements calculated by density functional theory (DFT), we developed a crystal attention graph neural network (CATGNN) model for predicting total phonon DOS of crystalline materials. The computational cost of training the CATGNN model is several orders of magnitude cheaper than full DFT calculations. We find that high vibrational similarity or phonon DOS overlap is not the only requirement to obtain high interfacial thermal conductance (ITC) instead, the average acoustic group velocity of heat source and heat sink for the acoustic branches in the phonon DOS overlap region is equally important in determining ITC. Pearson correlation analysis yields a few simple material descriptors that are strongly but negatively correlated with ITC. These easy-to-calculate material features combined with the proposed high average acoustic group velocity and phonon DOS overlap predicted by CATGNN model offer a new reliable and fast route for high-throughput screening of novel crystalline materials with desirable high ITC for phonon-mediated thermal management of wide bandgap electronics.</div></div>","PeriodicalId":18253,"journal":{"name":"Materials Today Physics","volume":"50 ","pages":"Article 101632"},"PeriodicalIF":10.0,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142857909","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Insights into the enhanced ORR activity of FeN4-embedded graphene through interface interactions with metal substrates: Electronic vs. geometric descriptors 通过与金属衬底的界面相互作用，深入了解嵌入fen4的石墨烯增强的ORR活性：电子与几何描述符

IF 1 2区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Materials Today Physics

Pub Date : 2025-01-01 DOI: 10.1016/j.mtphys.2024.101633

Silu Li , Donghai Wu , Lulu Gao , Jiahang Li , Gang Tang , Zaiping Zeng , Dongwei Ma

Recent experiments have revealed that the oxygen reduction reaction (ORR) performances of transition-metal and nitrogen codoped carbon (TM-N-C) can be drastically improved by interfacing with TM nanoparticles. However, the key factors that derive from this emerging composite SAC and can well correlate with the boosted ORR activity is still unclear. Herein, taking the FeN₄-embedded graphene (FeN₄-G) as example, we built a series of model heterointerface systems, by placing FeN₄-G on various common TM surfaces (denoted as FeN₄-M), to explore the enhancement origin. Based on extensive density functional theory calculations, we find that all the FeN₄-M systems exhibit higher ORR activity than the free-standing FeN₄-G, and even most FeN₄-M systems are much more active than the Pt(111) surface. Furthermore, for the descriptor construction, however there is no apparent correlation between the ORR activity and the electronic structures of Fe active centers, the ones that are closely relevant with ORR activity of the free-standing FeN₄-G. Instead, interestingly the interlayer distance between FeN₄-G and the underlying metal substrates, an intrinsic geometric structure parameter, has been identified to linearly correlate with the binding strengths of ORR intermediates and ORR overpotential well. Present work provides a novel insight into the structure-activity relationship of the composite SACs consisting of Fe-N-C and metal nanoparticles.

最近的实验表明，过渡金属与氮共掺杂碳（TM- n- c）的氧还原反应（ORR）性能可以通过与TM纳米颗粒的界面处理得到显著改善。然而，从这种新出现的复合SAC中衍生出的关键因素，以及与ORR活性增强相关的关键因素仍不清楚。本文以嵌入fen4的石墨烯（FeN4-G）为例，通过将FeN4-G放置在各种常见的TM表面（记为FeN4-M）上，构建了一系列模型异质界面系统，探索增强来源。基于广泛的密度泛函理论计算，我们发现所有的FeN4-M体系都比独立的FeN4-G表现出更高的ORR活性，甚至大多数FeN4-M体系都比Pt（111）表面更活跃。此外，在描述子结构中，与独立FeN4-G的ORR活性密切相关的Fe活性中心的电子结构与ORR活性之间没有明显的相关性。相反，有趣的是，FeN4-G与底层金属衬底之间的层间距离（一个固有的几何结构参数）已被确定与ORR中间体和ORR过电位的结合强度呈线性相关。本研究为铁-氮-碳和金属纳米颗粒组成的复合SACs的构效关系提供了新的见解。

{"title":"Insights into the enhanced ORR activity of FeN4-embedded graphene through interface interactions with metal substrates: Electronic vs. geometric descriptors","authors":"Silu Li , Donghai Wu , Lulu Gao , Jiahang Li , Gang Tang , Zaiping Zeng , Dongwei Ma","doi":"10.1016/j.mtphys.2024.101633","DOIUrl":"10.1016/j.mtphys.2024.101633","url":null,"abstract":"<div><div>Recent experiments have revealed that the oxygen reduction reaction (ORR) performances of transition-metal and nitrogen codoped carbon (TM-N-C) can be drastically improved by interfacing with TM nanoparticles. However, the key factors that derive from this emerging composite SAC and can well correlate with the boosted ORR activity is still unclear. Herein, taking the FeN<sub>4</sub>-embedded graphene (FeN<sub>4</sub>-G) as example, we built a series of model heterointerface systems, by placing FeN<sub>4</sub>-G on various common TM surfaces (denoted as FeN<sub>4</sub>-M), to explore the enhancement origin. Based on extensive density functional theory calculations, we find that all the FeN<sub>4</sub>-M systems exhibit higher ORR activity than the free-standing FeN<sub>4</sub>-G, and even most FeN<sub>4</sub>-M systems are much more active than the Pt(111) surface. Furthermore, for the descriptor construction, however there is no apparent correlation between the ORR activity and the electronic structures of Fe active centers, the ones that are closely relevant with ORR activity of the free-standing FeN<sub>4</sub>-G. Instead, interestingly the interlayer distance between FeN<sub>4</sub>-G and the underlying metal substrates, an intrinsic geometric structure parameter, has been identified to linearly correlate with the binding strengths of ORR intermediates and ORR overpotential well. Present work provides a novel insight into the structure-activity relationship of the composite SACs consisting of Fe-N-C and metal nanoparticles.</div></div>","PeriodicalId":18253,"journal":{"name":"Materials Today Physics","volume":"50 ","pages":"Article 101633"},"PeriodicalIF":10.0,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142857910","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Ferroelectric memristor and its neuromorphic computing applications 铁电记忆电阻器及其神经形态计算应用

IF 1 2区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Materials Today Physics

Pub Date : 2025-01-01 DOI: 10.1016/j.mtphys.2024.101607

Junmei Du , Bai Sun , Chuan Yang , Zelin Cao , Guangdong Zhou , Hongyan Wang , Yuanzheng Chen

Ferroelectric memristors, characterized by spontaneous polarization ferroelectric materials as a functional layer of memristor, yields unique ferroelectric resistive switching behaviours under a reversal electric field. This device demonstrates notable capability in the stable and precise emulation of synaptic and neuronal functions, analogous to those in the human brain, offering an attractive option for neuromorphic computing. With the development of nanotechnology and nano-ferroelectric materials, the advent of nano-ferroelectric memristors enables their incorporation into dense crossbar arrays, enhancing the density and efficiency of neuromorphic computing. In this review, we offer a comprehensive overview of ferroelectric memristor and its neuromorphic computing applications, including the recent progress, existing challenges and possible solutions, as well as future development direction.

铁电记忆电阻器的特点是由自发极化的铁电材料作为记忆电阻器的功能层，在反向电场下产生独特的铁电电阻开关行为。该装置在稳定和精确地模拟突触和神经元功能方面表现出显著的能力，类似于人脑中的功能，为神经形态计算提供了一个有吸引力的选择。随着纳米技术和纳米铁电材料的发展，纳米铁电忆阻器的出现使其能够集成到密集的横栅阵列中，从而提高了神经形态计算的密度和效率。本文综述了铁电忆阻器及其神经形态计算应用的最新进展、存在的挑战和可能的解决方案，以及未来的发展方向。

引用次数: 0

Corrigendum to ‘BiCuSeO based thermoelectric materials: Innovations and challenges’ [Mater. Today Phys. 35 (2023) 101104] 基于 BiCuSeO 的热电材料：创新与挑战' [Materials Today Physics 35 (2023) 101104] 的更正

IF 1 2区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Materials Today Physics

Pub Date : 2025-01-01 DOI: 10.1016/j.mtphys.2024.101621

Wenxin Tang , Wanyu Qian , Shuanglin Jia , Ke Li , Zhifang Zhou , Jinle Lan , Yuan-Hua Lin , Xiaoping Yang

引用次数: 0

Plasmonic photothermal superhydrophobic surface with nanotubes thermal insulating blanket for anti-icing and anti-frosting under weak light illumination 等离子体光热超疏水表面纳米管绝热层在弱光照下的防冰防霜研究

IF 1 2区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Materials Today Physics

Pub Date : 2025-01-01 DOI: 10.1016/j.mtphys.2024.101625

Huamei Zhong, Chengjie Xiang, Zhifeng Hu, Xinge Yang, Haoran Liu, Ruzhu Wang

Accumulation of ice and frost poses a substantial threat to the safe and efficient operation of transportation and energy infrastructures, such as aircraft, vessels, and wind turbines. While photothermal superhydrophobic surfaces have emerged as a promising solution for anti- and de-icing, the high thermal conductivity of metal substrates leads to large heat losses that limits the thermal efficiency of photothermal surfaces. In addition, the hard and brittle micro-nanostructure is an important obstacle limiting the practical application of superhydrophobic surfaces. Herein, the flexible poly(vinylidene fluoride) (PVDF) is employed to stabilize the rigid plasmonic titanium nitride (TiN) particles, and then a micro-hexagonal network structure containing fibers and knots is constructed on the surface of insulated titania nanotube layer by electrospinning. This photothermal superhydrophobic layer achieves a remarkable temperature increase of 75.3 °C under 1 Sun illumination, driven by high solar absorption, plasmon resonance, and enhanced thermal insulation. The surface exhibits excellent superhydrophobicity, enabling superior anti-icing and anti-frosting performance, even under reduced illumination (0.35 Sun). At −23 °C, the surface remains frost-free for up to 9 h and can melt ice within 300 s. This design offers significant potential for applications in transportation, energy systems, and other critical infrastructures.

冰和霜的积累对交通和能源基础设施（如飞机、船舶和风力涡轮机）的安全和有效运行构成了重大威胁。虽然光热超疏水表面已经成为一种很有前途的防冰和除冰解决方案，但金属基板的高导热性导致大量热损失，限制了光热表面的热效率。此外，硬脆的微纳米结构是限制超疏水表面实际应用的重要障碍。本文采用柔性聚偏氟乙烯（PVDF）稳定刚性等离子体氮化钛（TiN）颗粒，然后通过静电纺丝在绝缘二氧化钛纳米管层表面构建含有纤维和结的微六角形网络结构。该光热超疏水层在1个太阳照射下，由于高太阳吸收率、等离子体共振和增强的绝热性，温度提高了75.3°C。表面表现出优异的超疏水性，即使在较低的光照（0.35太阳）下也具有优异的防结冰和防霜性能。在-23°C的温度下，表面保持无霜长达9小时，可以在300秒内融化冰。这种设计为交通运输、能源系统和其他关键基础设施的应用提供了巨大的潜力。

{"title":"Plasmonic photothermal superhydrophobic surface with nanotubes thermal insulating blanket for anti-icing and anti-frosting under weak light illumination","authors":"Huamei Zhong, Chengjie Xiang, Zhifeng Hu, Xinge Yang, Haoran Liu, Ruzhu Wang","doi":"10.1016/j.mtphys.2024.101625","DOIUrl":"10.1016/j.mtphys.2024.101625","url":null,"abstract":"<div><div>Accumulation of ice and frost poses a substantial threat to the safe and efficient operation of transportation and energy infrastructures, such as aircraft, vessels, and wind turbines. While photothermal superhydrophobic surfaces have emerged as a promising solution for anti- and de-icing, the high thermal conductivity of metal substrates leads to large heat losses that limits the thermal efficiency of photothermal surfaces. In addition, the hard and brittle micro-nanostructure is an important obstacle limiting the practical application of superhydrophobic surfaces. Herein, the flexible poly(vinylidene fluoride) (PVDF) is employed to stabilize the rigid plasmonic titanium nitride (TiN) particles, and then a micro-hexagonal network structure containing fibers and knots is constructed on the surface of insulated titania nanotube layer by electrospinning. This photothermal superhydrophobic layer achieves a remarkable temperature increase of 75.3 °C under 1 Sun illumination, driven by high solar absorption, plasmon resonance, and enhanced thermal insulation. The surface exhibits excellent superhydrophobicity, enabling superior anti-icing and anti-frosting performance, even under reduced illumination (0.35 Sun). At −23 °C, the surface remains frost-free for up to 9 h and can melt ice within 300 s. This design offers significant potential for applications in transportation, energy systems, and other critical infrastructures.</div></div>","PeriodicalId":18253,"journal":{"name":"Materials Today Physics","volume":"50 ","pages":"Article 101625"},"PeriodicalIF":10.0,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142804624","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0