Materials Today Physics最新文献_第3页

Effect of magnetic entropy in the thermoelectric properties of Fe-doped Fe2VAl full-Heusler alloy 磁熵对掺铁的 Fe2VAl 全赫斯勒合金热电性能的影响

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

Materials Today Physics

Pub Date : 2024-10-11 DOI: 10.1016/j.mtphys.2024.101568

The effect of spin entropy on the transport of heat/charge carriers in the Fe-doped full-Heusler alloy Fe_2+xVAl_1-x with x = 0–0.1 has been studied through low-temperature magnetic and thermoelectric measurements. Magnetization (M) measurements confirm itinerant-electron weak-ferromagnetic behavior. A systematic increase of the magnetic transition temperature T_C (from 40 K to 223 K) and of the saturation magnetization (from 0.13 to 0.41μ_B/Fe) with increasing Fe doping (from x = 0 to 0.1) is observed. Applying a magnetic field causes significant suppression of the Seebeck coefficient (S) and the entropy term (S/T) with a negative magnetoresistance near T_C for all weak-ferromagnetic samples, demonstrating a clear effect of spin fluctuations. Analyzing M(T) and S(T), we rule out sizeable magnon drag contributions. A large spin fluctuations-induced enhancement in the thermoelectric power factor PF of about 18 % is achieved for x = 0.1 near T_C when compared to measurements in a magnetic field of 7 T. The actual improvement in PF is even much higher, as the S shows a significant enhancement (about 34 %) compared to the estimated diffusion term of S(T) at T_C. The number of point defects also increases with Fe doping, causing a significant reduction of the lattice thermal conductivity. This study demonstrates the role of spin fluctuations in enhancing the thermopower/thermoelectric performance of Fe-doped Fe₂VAl and opens a vista for the strategy's applicability for various thermoelectric materials.

通过低温磁性和热电测量，研究了自旋熵对 x = 0 - 0.1 的掺铁全赫斯勒合金 Fe2+xVAl1-x 中热/电荷载流子传输的影响。磁化（M）测量证实了巡回电子弱铁磁行为。随着铁掺杂量的增加（从 x = 0 到 0.1），磁转变温度 TC（从 40 K 到 223 K）和饱和磁化率（从 0.13 到 0.41μB/Fe）出现了系统性增长。对于所有弱铁磁性样品，施加磁场会显著抑制塞贝克系数（S）和熵项（S/T），并在 TC 附近产生负磁阻，这表明自旋波动具有明显的影响。通过分析 M(T) 和 S(T)，我们排除了可观的磁子阻力贡献。与 7 T 磁场中的测量结果相比，x = 0.1 时 TC 附近的热电功率因数 PF 在自旋波动的诱导下大幅提高了约 18%。由于 S 在 TC 时比估计的 S(T) 扩散项有显著提高（约 34%），PF 的实际提高幅度甚至更大。点缺陷的数量也随着铁的掺杂而增加，导致晶格热导率显著降低。这项研究证明了自旋波动在提高掺铁 Fe2VAl 的热功率/热电性能中的作用，并为该策略在各种热电材料中的应用开辟了前景。

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引用次数: 0

Wrinkled layers lead to high in-plane zT values in hexagonal CaAgSb 皱褶层导致六方 CaAgSb 具有较高的面内 zT 值

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

Materials Today Physics

Pub Date : 2024-10-10 DOI: 10.1016/j.mtphys.2024.101566

Layered thermoelectric materials (LTMs) have attracted great attention due to their anisotropic transport behaviors that provide an opportunity to disentangle the interrelated electrical and thermal conductivities. In this study, we found that hexagonal CaAgSb (h-CaAgSb) possesses a lower lattice thermal conductivity and a higher electrical conductivity simultaneously along the in-plane direction when compared with the out-of-plane direction. The low in-plane lattice thermal conductivity mainly originates from the low group velocity of longitudinal acoustic phonon modes. Meanwhile, strong anharmonicity is discovered for the low-lying optical phonon modes. On the other hand, the high in-plane electrical conductivity relies on the small effective mass. Thus, both p-type and n-type h-CaAgSb exhibit a high zT over 2.0 along the in-plane direction at the optimal carrier concentrations. The anisotropic transport properties of h-CaAgSb reported in this work may provide guidance to the experiments. More importantly, the physical insights revealed for the disentangled electrical and thermal transport properties may pave the way for finding other excellent LTMs and optimizing the thermoelectric performance through structure engineering.

层状热电材料（LTMs）因其各向异性的输运行为而备受关注，这为我们解开相互关联的电导率和热导率提供了机会。在这项研究中，我们发现六方 CaAgSb（h-CaAgSb）与面外方向相比，在面内方向同时具有较低的晶格热导率和较高的电导率。面内晶格热导率低的主要原因是纵向声子模式的群速度较低。同时，还发现低洼光学声子模式具有很强的非谐波性。另一方面，高面内电导率依赖于较小的有效质量。因此，在最佳载流子浓度下，p 型和 n 型 h-CaAgSb 沿面内方向都表现出超过 2.0 的高 zT。这项工作中报告的 h-CaAgSb 各向异性输运特性可为实验提供指导。更重要的是，本文所揭示的电学和热学输运特性相分离的物理原理，可为寻找其他优异的低温金属和通过结构工程优化热电性能铺平道路。

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引用次数: 0

Cu−based bimetallic sites' p-d orbital hybridization promotes CO asymmetric coupling conversion to C2 products 铜基双金属位点的 p-d 轨道杂化促进 CO 不对称耦合转化为 C2 产物

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

Materials Today Physics

Pub Date : 2024-10-10 DOI: 10.1016/j.mtphys.2024.101565

Hampered by sluggish C−C coupling kinetics, the low selectivity and efficiency have limited industrial applications of CO₂ reduction into valuable multi-carbon products. A direct coupling of CO molecules or their coupling after hydrogenation, followed by the final synthesis of C₂ products, can help to overcome these limitations potentially. In this study, a detailed high-throughput screening of bimetallic site catalysts comprising copper (Cu) and 28 other metal (M) atoms was conducted. The metal atoms Cu and M were anchored on a carbon nanotube (CNT) with six nitrogen (N₆) defects (CuMN₆@CNT), which possesses effective dual active sites for C−C coupling. The calculated results demonstrate that the CuGaN₆@CNT catalyst exhibited favorable selectivity, with low theoretical overpotentials of −0.23 and −0.34 eV for ethanol and ethylene, respectively, surpassing most reported catalysts. The synergistic effect of Ga and Cu sites, along with their p-d states hybridization, results in an enhancement of Cu's d state dispersion and energy barriers reduction for C−C coupling. Additionally, the strain effect of the substrate CNT exhibits a direct correlation with the catalytic performance of CuGaN₆@CNT by adjusting the d-band center of the Cu site and p-band center of the Ga site. These findings provide a novel insights into the electrocatalytic reduction of CO into valuable C₂ products using bimetallic single atom catalyst, offering significant guidance for future research endeavors in this field.

由于 C-C 偶联动力学缓慢，选择性和效率较低，限制了将 CO2 还原成有价值的多碳产品的工业应用。直接耦合 CO 分子或在氢化后耦合 CO 分子，然后最终合成 C2 产物，有助于克服这些潜在的局限性。本研究对由铜（Cu）原子和 28 个其他金属（M）原子组成的双金属位点催化剂进行了详细的高通量筛选。金属原子 Cu 和 M 被锚定在具有六个氮（N6）缺陷的碳纳米管（CNT）上（CuMN6@CNT），该碳纳米管具有 C-C 偶联的有效双活性位点。计算结果表明，CuGaN6@CNT 催化剂具有良好的选择性，对乙醇和乙烯的理论过电位分别为 -0.23 和 -0.34 eV，低于大多数已报道的催化剂。Ga 和 Cu 位点的协同效应以及它们的 p-d 态杂化作用增强了 Cu 的 d 态分散性，降低了 C-C 耦合的能垒。此外，通过调整铜位点的 d 波段中心和镓位点的 p 波段中心，基底 CNT 的应变效应与 CuGaN6@CNT 的催化性能直接相关。这些发现为利用双金属单原子催化剂电催化将 CO 还原成有价值的 C2 产物提供了新的见解，为该领域未来的研究工作提供了重要指导。

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引用次数: 0

CoFe2O4-BaTiO3 core-shell-embedded flexible polymer composite as an efficient magnetoelectric energy harvester 作为高效磁电能量收集器的 CoFe2O4-BaTiO3 芯壳嵌入式柔性聚合物复合材料

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

Materials Today Physics

Pub Date : 2024-10-10 DOI: 10.1016/j.mtphys.2024.101567

Flexible magnetoelectric (ME) generators gained immense interest due to the broad applications in wearable and Internet of Things (IoT)-based devices. The key to achieving high energy conversion performance of 0–3 type ME composite films is the prevention of filler aggregation in the polymer matrix and accessing the full potential of intrinsic properties of filler. To achieve high performance, a flexible ME composite film was fabricated by homogeneous distribution of magnetostrictive CoFe₂O₄-BaTiO₃ core-shell (CBCS) fillers into piezoelectric polyvinylidene fluoride (PVDF) polymer. The ME composite film generates an enhanced energy conversion efficiency by optimizing the shell thickness of CBCS and maximizing the electroactive β-phase at the BaTiO₃ shell-PVDF interfacial region. The observed ME coefficient of the film reached up to 710 mV/cm∙Oe. Multiphysics simulations based on the finite element analysis were adopted to investigate the role of BaTiO₃ shell thickness on the performance of ME film. This study paves the way to achieve higher filler loading content in the ME composite films to develop an efficient, flexible ME generator for eco-friendly permanent power sources.

柔性磁电（ME）发电机在可穿戴设备和物联网（IoT）设备中的广泛应用引起了人们的极大兴趣。0-3 型 ME 复合薄膜要实现高能量转换性能，关键在于防止填料在聚合物基体中聚集，并充分发挥填料固有特性的潜力。为了实现高性能，我们将磁致伸缩 CoFe2O4-BaTiO3 核壳（CBCS）填料均匀分布在压电聚偏氟乙烯（PVDF）聚合物中，制备出了一种柔性 ME 复合薄膜。通过优化 CBCS 的壳厚度和最大化 BaTiO3 壳-PVDF 界面区域的电活性 β 相，ME 复合薄膜产生了更高的能量转换效率。观察到的薄膜 ME 系数高达 710 mV/cm∙Oe。基于有限元分析的多物理场模拟研究了 BaTiO3 壳厚度对 ME 薄膜性能的影响。这项研究为在 ME 复合薄膜中实现更高的填料含量以开发高效、灵活的 ME 发电机铺平了道路，从而为环保型永久电源提供了可能。

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引用次数: 0

Efficient and stable perovskite solar cells based on multi-active sites 5-amino-1,3,4-thiadiazole-2-thiol modified interface 基于多活性位点 5-氨基-1,3,4-噻二唑-2-硫醇修饰界面的高效稳定的过氧化物太阳能电池

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

Materials Today Physics

Pub Date : 2024-10-02 DOI: 10.1016/j.mtphys.2024.101564

The highest certification efficiency of perovskite solar cells (PSCs) has reached 26.7 %. However, the high defect density on the surface of perovskite films prepared by low temperature solution method and the energy mismatch between the carrier transport layers and perovskite layer (PVK) greatly limit the performance improvement of PSCs. The introduction of passivating agent to modify the perovskite interface and grain boundary can reduce the defect density, coordinate the energy level effectively, and improve the efficiency and stability of devices. A Lewis base molecule 5-amino-1,3,4-thiadiazole-2-thiol (AMTD) with multiple active sites is introduced at the interface between PVK and hole transport layer (HTL). The electron-rich groups, such as = S, –S–, –NH₂, –N on AMTD, passivate the positive electrical defects on the interface and grain boundary, and increase carrier transport efficiency. The interfacial energy level array is optimized to achieve more efficient charge transportation. In addition, the modified of AMTD has a significant protective effect on the perovskite, which inhibit the moisture erosion of in environment. Consequently, the AMTD-optimized device achieves a power conversion efficiency (PCE) of 24.13 %, compared to the efficiency of 21.62 % for pristine device. The stability of the devices is improved greatly.

过氧化物太阳能电池（PSC）的最高认证效率已达到 26.7%。然而，低温溶液法制备的过氧化物薄膜表面缺陷密度高，载流子传输层与过氧化物层（PVK）之间能量不匹配，极大地限制了过氧化物太阳能电池性能的提高。引入钝化剂对包晶石界面和晶界进行改性，可以降低缺陷密度，有效协调能级，提高器件的效率和稳定性。在 PVK 和空穴传输层（HTL）的界面上引入了具有多个活性位点的路易斯碱分子 5-氨基-1,3,4-噻二唑-2-硫醇（AMTD）。AMTD 上的富电子基团（如 = S、-S-、-NH2、-N）可钝化界面和晶界上的正电缺陷，提高载流子传输效率。通过优化界面能级阵列，可实现更高效的电荷传输。此外，AMTD 的改性对包晶石具有显著的保护作用，可抑制环境中的湿气侵蚀。因此，经过 AMTD 优化的器件实现了 24.13% 的功率转换效率 (PCE)，而原始器件的效率仅为 21.62%。器件的稳定性也大大提高。

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引用次数: 0

Enhanced non-equilibrium Peltier cooling through electron gas expansion: A Monte Carlo simulation study 通过电子气体膨胀增强非平衡珀尔帖制冷：蒙特卡罗模拟研究

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

Materials Today Physics

Pub Date : 2024-09-28 DOI: 10.1016/j.mtphys.2024.101561

We demonstrate enhanced Peltier cooling at the nanoscale using geometrical constriction. This nozzle structure leads to electron expansion under an applied bias, which in turn results in additional cooling. This extra cooling enhances the overall Peltier effect when the electrons are out of equilibrium with the lattice. An ensemble Monte Carlo simulation is used to demonstrate the non-equilibrium expansion of an electron gas using nanoscale trapezoidal geometric confinement. The proposed device operates under steady-state conditions, providing enhanced cooling compared to a one-dimensional flat geometry. We observe a five-fold increase in both the maximum cooling temperature and cooling power density, reaching more than 5 kW/cm², when comparing the trapezoidal geometry to the regular flat geometry.

我们展示了利用几何收缩在纳米尺度上增强的珀尔帖冷却。这种喷嘴结构导致电子在外加偏压下膨胀，进而产生额外冷却。当电子与晶格失去平衡时，这种额外的冷却会增强整体的珀尔帖效应。利用集合蒙特卡洛模拟演示了使用纳米级梯形几何约束的电子气体的非平衡膨胀。与一维平面几何相比，所提出的装置在稳态条件下运行，提供了更强的冷却能力。我们观察到，梯形几何与普通平面几何相比，最大冷却温度和冷却功率密度都提高了五倍，达到 5 kW/cm2 以上。

引用次数: 0

A high stretchability micro-crack tactile sensor system based on strain-isolation substrate 基于应变隔离基底的高拉伸性微裂缝触觉传感器系统

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

Materials Today Physics

Pub Date : 2024-09-27 DOI: 10.1016/j.mtphys.2024.101562

The integration of inflexible constituents onto pliable substrates is widely acknowledged as the most pragmatic approach for the realization of stretchable electronics. Nevertheless, the assurance of enduring connectivity between rigid electrode components and these compliant substrates poses a formidable quandary. In the scope of our investigation, we proffer a resolution by conceptualizing a PDMS substrate replete with strain isolation partitions, which can generate Young's modulus difference of approximately 30 times. These partitions efficaciously safeguard the steadfast linkage between rigid components and electrodes, even under diverse strain provocations, a stable connection can be maintained even when able to withstand strain exceeding 120 %. Using this substrate, we constructed a visual deformation sensing system based on microcrack type sensors. Compared with traditional flexible substrates (2 % strain), systems based on strain isolation substrates have better tensile stability (10 % strain). This groundbreaking innovation bestows stretchable micro-crack strain-sensing systems the resilience to contend with the potentially formidable rigors of everyday application.

将非柔性元件集成到柔性基底上被公认为是实现可拉伸电子器件的最实用方法。然而，如何确保刚性电极元件与这些柔性基底之间的持久连接是一个棘手的难题。在我们的研究范围内，我们提出了一种解决方案，即在 PDMS 衬底上设置应变隔离隔板，可产生约 30 倍的杨氏模量差。这些隔板能有效保护刚性元件和电极之间的稳定连接，即使在不同的应变刺激下，也能保持稳定的连接，甚至能承受超过 120% 的应变。利用这种基板，我们构建了一种基于微裂缝型传感器的视觉形变传感系统。与传统的柔性基底（2% 应变）相比，基于应变隔离基底的系统具有更好的拉伸稳定性（10% 应变）。这一突破性创新赋予了可拉伸微裂纹应变传感系统以强大的应变能力，使其能够应对日常应用中潜在的严峻考验。

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引用次数: 0

Achieving high thermal conductivity and strong bending strength diamond/aluminum composite via nanoscale multi-interface phase structure engineering 通过纳米级多界面相结构工程实现高导热性和强抗弯强度的金刚石/铝复合材料

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

Materials Today Physics

Pub Date : 2024-09-27 DOI: 10.1016/j.mtphys.2024.101563

Diamond/aluminum composites, as a new generation of thermal management materials, are caught in the dilemma between inhibiting the formation of Al₄C₃ and improving the performance. Herein, we proposed a strategy for nanoscale multi-interface phase structure engineering, utilizing a combination of magnetron sputtering and vacuum heat treatment to obtain diamond particles with nanoscale TiC-Ti layers. Prolonging the vacuum heating time increases the content of TiC, but results in significant differences in the morphology and coverage of TiC formed on the diamond(100) and (111) facets. First-principles calculations reveal that the work of adhesion and C-Ti reaction tendency of diamond(100)/Ti are stronger than those of diamond(111)/Ti, clarifying the difference in interfacial properties between diamond/Ti and diamond/TiC. Diamond-TiC-Ti configuration obtained in advance contributes to fabricating the composite with diamond-TiC-Al(Al₃Ti) structure, and the multi-interface phase structure is beneficial to improve the interface bonding, adjust the acoustic mismatch, and inhibit the formation of Al₄C₃. (800 °C 0.5 h)@Ti-coated diamond(100 μm)/aluminum composite with the multi-interface phase exhibits excellent thermal conductivity(646 W m⁻¹ K⁻¹) and outstanding bending strength(358 MPa), exceeding 90 % of the theoretical prediction of the differential effective medium model. The performance of (800 °C 0.5 h)@Ti-coated diamond/aluminum composite is about 30 % higher than that of traditional Ti-coated diamond/aluminum composite. The TiC layer formed by increasing the heat treatment time is thicker and discontinuous, leading to a decrease in the thermal conductivity of the composite and a weakening effect of Al₄C₃ inhibition. We clarified the formation mechanism of interface structure related to diamond orientation by multi-scale characterization. Based on the thermal conductivity prediction models, the interface structures corresponding to different diamond orientations were considered, and the predicted values showed good consistency with the experimental results. By interface modification engineering, we overcome the dilemma of introducing modified layer to inhibit Al-C reaction while leading to additional interface thermal resistance, providing insights into the interfacial thermal transport mechanism.

金刚石/铝复合材料作为新一代热管理材料，在抑制 Al4C3 的形成和提高性能之间进退两难。在此，我们提出了一种纳米级多界面相结构工程策略，利用磁控溅射和真空热处理相结合的方法，获得具有纳米级 TiC-Ti 层的金刚石颗粒。延长真空加热时间会增加 TiC 的含量，但会导致在金刚石（100）和（111）面上形成的 TiC 的形态和覆盖率出现显著差异。第一性原理计算显示，金刚石（100）/钛的附着功和 C-Ti 反应倾向强于金刚石（111）/钛，从而阐明了金刚石/钛和金刚石/TiC 之间界面性质的差异。提前获得的金刚石-TiC-Ti 构型有助于制备金刚石-TiC-Al(Al3Ti)结构的复合材料，多界面相结构有利于改善界面结合、调整声学失配和抑制 Al4C3 的形成。(800 °C 0.5 h)@Ti 涂层金刚石（100 μm）/铝多界面相复合材料表现出优异的热导率（646 W m-1 K-1）和出色的抗弯强度（358 MPa），超过微分有效介质模型理论预测值的 90%。(800 °C 0.5 h)@Ti 涂层金刚石/铝复合材料的性能比传统的 Ti 涂层金刚石/铝复合材料高出约 30%。增加热处理时间形成的 TiC 层更厚且不连续，导致复合材料的热导率降低，Al4C3 的抑制作用减弱。我们通过多尺度表征阐明了与金刚石取向相关的界面结构形成机制。在热导率预测模型的基础上，考虑了不同金刚石取向对应的界面结构，预测值与实验结果具有良好的一致性。通过界面改性工程，我们克服了引入改性层抑制 Al-C 反应的同时导致界面热阻增加的两难问题，为界面热传输机制的研究提供了启示。

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引用次数: 0

Improving machine-learning models in materials science through large datasets 通过大型数据集改进材料科学中的机器学习模型

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

Materials Today Physics

Pub Date : 2024-09-25 DOI: 10.1016/j.mtphys.2024.101560

The accuracy of a machine learning model is limited by the quality and quantity of the data available for its training and validation. This problem is particularly challenging in materials science, where large, high-quality, and consistent datasets are scarce. Here we present alexandria, an open database of more than 5 million density-functional theory calculations for periodic three-, two-, and one-dimensional compounds. We use this data to train machine learning models to reproduce seven different properties using both composition-based models and crystal-graph neural networks. In the majority of cases, the error of the models decreases monotonically with the training data, although some graph networks seem to saturate for large training set sizes. Differences in the training can be correlated with the statistical distribution of the different properties. We also observe that graph-networks, that have access to detailed geometrical information, yield in general more accurate models than simple composition-based methods. Finally, we assess several universal machine learning interatomic potentials. Crystal geometries optimised with these force fields are very high quality, but unfortunately the accuracy of the energies is still lacking. Furthermore, we observe some instabilities for regions of chemical space that are undersampled in the training sets used for these models. This study highlights the potential of large-scale, high-quality datasets to improve machine learning models in materials science.

机器学习模型的准确性受限于可用于训练和验证的数据的质量和数量。这个问题在材料科学领域尤其具有挑战性，因为材料科学领域缺乏大规模、高质量和一致性的数据集。在这里，我们介绍亚历山大（alexandria），这是一个开放式数据库，包含 500 多万个周期性三维、二维和一维化合物的密度泛函理论计算结果。我们利用这些数据训练机器学习模型，使用基于成分的模型和晶体图神经网络重现七种不同的性质。在大多数情况下，模型的误差会随着训练数据的增加而单调减少，但有些图网络在训练集规模较大时似乎会达到饱和。训练中的差异可能与不同属性的统计分布有关。我们还观察到，与简单的基于组成的方法相比，能够获取详细几何信息的图网络一般能生成更精确的模型。最后，我们评估了几种通用的机器学习原子间势。使用这些力场优化的晶体几何图形质量非常高，但遗憾的是能量的准确性仍然不足。此外，我们还观察到这些模型的训练集中取样不足的化学空间区域存在一些不稳定性。这项研究凸显了大规模、高质量数据集在改进材料科学领域机器学习模型方面的潜力。

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引用次数: 0

Inverse and conventional dual magnetocaloric effects in Ni substituted Y-type Sr2Zn2-xNixFe12O22 hexaferrites 镍替代 Y 型 Sr2Zn2-xNixFe12O22 六元晶中的反向和常规双磁效应

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

Materials Today Physics

Pub Date : 2024-09-21 DOI: 10.1016/j.mtphys.2024.101559

The effects of Ni substitution on magnetic and magnetocaloric effect (MCE) are investigated in polycrystalline Y-type hexaferrites of Sr₂Zn_2-xNi_xFe₁₂O₂₂ (x = 0.0, 0.8, and 2.0). With the increasing of temperature, the M-T curves indicate successive magnetic structure transitions exist in Sr₂Zn_2-xNi_xFe₁₂O₂₂ (x = 0.0, 0.8, and 2.0), which play significant roles in MCE behaviors. As the Ni²⁺ doping ratio increases, the shape of

- Δ S_{M} - T

curves near room temperature evolves gradually from a table-like to a peak-like form. Particularly, a significant contrast between CMCE and IMCE is observed below 100 K, whose behavior can be inherently exploited for heat sink in magnetic refrigeration applications. Among the samples in this series, Sr₂Zn_1.2Ni_0.8Fe₁₂O₂₂ plays the best CMCE and IMCE performances, with the maximum magnetic entropy change (

- Δ S_{M}^{\max}

) values of 0.78 J/kg K at 354 K and −0.56 J/kg K at 16 K for

Δ H = 50 k O e

, respectively. Our work demonstrates that Sr₂Zn_2-xNi_xFe₁₂O₂₂ hexaferrites have great potential to be tailored for magnetic refrigeration with special needs such as different operating temperature zones, Ericsson cycle or heat sink at refrigeration.

研究了在 Sr2Zn2-xNixFe12O22（x = 0.0、0.8 和 2.0）的多晶 Y 型六元晶中镍替代对磁性和磁致效应（MCE）的影响。随着温度的升高，M-T 曲线表明在 Sr2Zn2-xNixFe12O22（x = 0.0、0.8 和 2.0）中存在连续的磁结构转变，这些转变在 MCE 行为中起着重要作用。随着 Ni2+ 掺杂比的增加，-ΔSM-T 曲线在室温附近的形状逐渐从台状演变成峰状。特别是在 100 K 以下，CMCE 和 IMCE 之间出现了明显的反差，其特性可在磁制冷应用中作为散热器加以利用。在该系列样品中，Sr2Zn1.2Ni0.8Fe12O22 的 CMCE 和 IMCE 性能最佳，在 ΔH=50kOe 时，其在 354 K 和 16 K 的最大磁熵变化（-ΔSMmax）值分别为 0.78 J/kg K 和 -0.56 J/kg K。我们的工作表明，Sr2Zn2-xNixFe12O22 六价铁氧体具有巨大的潜力，可根据不同的工作温度区、制冷时的爱立信循环或散热器等特殊需求定制磁制冷。

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引用次数: 0