ADVANCED MATERIALS
·
2025
·
IF 26.8
Lei Zhuang,Zihao Wen,Yiwen Liu,Jing Yang,Hulei Yu,Yanhui Chu
Understanding the behavior of high-entropy carbides (HECs) under oxygen-containing environments is of particular importance for their promising applications in structural components, catalysis, and energy-related fields. Herein, the structural evolution of (Ta, Ti, Cr, Nb)C (HEC-1) nanoparticles (NPs) is tracked in situ during the oxidation at the atomic scale by using an open-cell environmental aberration-corrected scanning transmission electron microscope. Three key stages are clearly discerned during the oxidation of HEC-1 NPs at the atomic level below 900 °C: i) increased amorphization of HEC-1 NPs from 300 to 500 °C due to the energetically favorable formation of carbon vacancies and substitution of carbon with oxygen atoms; ii) nucleation and subsequent growth of locally ordered nanocluster intermediates within the generated amorphous oxides from 500 to 800 °C; and iii) final one-step crystallization of non-equimolar MeO 2 and Me 2 O 5 (Me = metallic elements, Ta, Ti, Cr, and Nb) high-entropy oxides above 800 °C, accompanied with the reduction in atomic defects. This result is further confirmed by theoretical calculations that these observed high-entropy oxide phases are thermodynamically preferable to generate above 830 °C. The study provides direct evidence of the ordered–disordered–ordered structural transition of HECs during oxidation.
研究领域:
材料科学
·
纳米技术
·
表面科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
·
2023
·
IF 5.7
Guangjin Chen,Cuiwei Li,Huaiming Jia,Hao Li,Siyuan Li,Bo Gong,Linan An,Kepi Chen
Five equimolar multicomponent oxides were synthesized by replacing one of five cations in (Ce 0.2 Zr 0.2 Ti 0.2 Sn 0.2 Hf 0.2 )O 2 with Ca 2+ . The results reveal that except for the one in which Ce 4+ replaced by Ca 2+ , the other four components can form single-phase high-entropy fluorite oxides (HEFOs) at different temperatures, which indicates that Ce 4+ is very important for the formation of single-phase HEFOs. The sintering behavior, lattice parameter and properties containing density, porosity, flexural strength and thermal conductivity of the four single-phase HEFOs were investigated. With the change of substituted ions, grain size, relative density, flexural strength and thermal conductivity of the materials vary greatly, which are correlated to the size disorder and mass disorder of these materials. The results of this paper provide a reference for the composition designing and performance tailoring of equimolar HEFOs.
研究领域:
材料科学
·
无机化学
✓ 已验证
DOI
高影响因子
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
·
2023
·
IF 5.7
Xiaohui Tang,Hongjun Zhang,Fangzhe Li,Dongliang Wang,Yong Huang,Hua Ke
Dielectric capacitors play an increasingly important role in power systems because of their fast charging and discharging speed. Applications are usually limited due to the low W rec . We design materials with high values of Δ P ( P max - P r ) and recoverable energy storage density( W rec ) from the high entropy perspective. Two single phases with a large Curie temperature T c difference have been selected, which leads to the enlarged entropy. The ceramics (Bi 0.85 Nd 0.1 Sm 0.05 ) 1- x Ba x )(Fe 1- x Ti x )O 3 (BNSBFT x ) are prepared by the solid-state reaction. As x increases, the corresponding configuration entropy( S config ) goes from 1.4 R to 1.52 R. The increased entropy destroys the long-range order, accompanied by the reduced remanent polarization( P r ) and the improved W rec . The W rec of BNSBFT 0.5 ceramics reaches 4.9 J/cm 3 at a low field of 250 kV/cm. Both temperature change(∼ 0.5% from 30 °C to 140 °C) and frequency variation(∼ 4.8% from 1 Hz∼50 Hz) in W rec show excellent stability.
研究领域:
材料科学
·
能源工程
✓ 已验证
产品关联
DOI
高影响因子
Nano-Micro Letters
·
2024
·Vol. 17
·期 1
·1-15
·
IF 31.6
Wang Honghan,Xiao Xinyu,Zhai Shangru,Xue Chuang,Zheng Guangping,Zhang Deqing,Che Renchao,Cheng Junye
The strengthening mechanism of spontaneous orientation polarization of anisotropic equivalent dipoles within high-entropy alloys (HEAs) is proposed for enhancing dielectric attenuation of HEAs.
The source of carbon supporter is expanded to the biomass category, which can construct the shell-core heterointerfaces with HEAs by means of a reformative carbothermal shock method.
The sample carbonized cellulose paper/HEAs-Mn 2.15 achieves efficient electromagnetic wave absorption of -51.35 dB at an ultra-thin thickness of 1.03 mm.
This work combines theoretical calculations and electromagnetic simulations to propose feasible strategies for the design and application of electromagnetic functional devices such as ultra-wideband bandpass filter.
研究领域:
材料科学
·
电磁学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Energy & Environmental Science
·
2024
·
IF 32.4
Qiyan Zhang,Dongmou Li,Yueqi Zhong,Yuna Hu,Shuangwu Huang,Shuxiang Dong,Q. M. Zhang
Electrostatic capacitors based on polymer dielectrics are essential components in advanced electronic and electrical power systems. An urgent challenge, however, is how to improve their capacitive performance at high temperatures to meet the rising demand for electricity in a harsh-environment present in the emergent applications such as electric vehicles, renewable energy, and aerospace systems. Here, we report a low-entropy amorphous polymer with locally extended chain conformation comprising high-Tg poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) blended with polystyrene (PS) that exhibits an energy density as high as 5.5 J cm−3 with an efficiency of >90% at an electric field of 600 MV m−1 at 150 °C, outperforming the existing dielectric polymers. Our results reveal that regulating the conformation entropy of polymer chains introduces a favorable locally extended polymer chain conformation, resulting in dense chain packing with short-range ordered but long-range disordered microstructures, and inhibits the transport of electrons in dielectric polymers, consequently, leading to the substantial improvements of capacitive performance at elevated temperatures. This low-entropy approach is scalable, general, ultra-low-cost and simple, paving the way for mass fabrication of high-performance and high-quality polymer films required for high-temperature film capacitors.
研究领域:
材料科学
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能源存储
·
高分子化学
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2024
·
IF 5.1
Jianjian Wang,Yue Yu,Zhiqiang Li,Hualin Wang,Shimin Liu,Tingting Yao,Weiwei Jiang,Nan Wang,Chaoqian Liu,Wanyu Ding,Zhihua Zhang,Chuang Dong
Multi-component high entropy oxides (HEOs) have attracted enormous attention due to their unique structures and potential applications. The conventional selection strategy to obtain HEOs is to search for equimolar cationic systems to maximize configurational entropy and avoid phase separation. We previously explored non-equimolar cationic rocksalt structure Mg–Co–Ni–Cu–Zn–O HEOs using cluster-plus-glue-atom model. In this paper, the mixing entropy, enthalpy and Gibbs free energy of constructed superclusters were numerically calculated and compared with the correlated crystal structure based on recent studies. It indicated the Gibbs free energy rather than mixing entropy agrees well with the phase stability of HEOs. Mg 28 Co 17 Ni 19 Cu 16 Zn 16 O 96 shows the optimal phase stability which is related to the lowest Gibbs free energy, reflecting a regular octahedral environment preferred by the cation composition in the system. Enthalpy and entropy are among important design criteria in determining the phase stability of HEOs but the function of enthalpy is obviously higher than that of entropy. This study provides a comprehensive way to access HEOs which is undoubtedly very important for the development of other non-equimolar cationic high entropy materials such as carbides , silicides , borides or nitrides .
研究领域:
材料科学
·
热力学
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2024
·
IF 13.3
Zhemin Chen,Yongping Pu,Yating Ning,Chunhui Wu,Lei Zhang,Bo Wang,Xuqing Zhang
Eco-friendly dielectric ceramics with excellent energy storage performance and dielectric temperature stability are the kernel parts of pulsed power devices in the next-generation. However, the contradiction between high breakdown electric field ( E b )and maximum polarization ( P max ) restricts the improvement of comprehensive performance. Herein, we report a novel strategy of entropy engineering in the superparaelectric state to address the above concerns. On the one hand, near-linear polarization response can be achieved in the superparaelectric state, which can be beneficial to obtain a large P max , low remnant polarization ( P r ) and slim P-E loops. On the other hand, the improvement of configuration entropy (Δ S config ) is conducive to refining grain size and domain size, enhancing bandgap width, and suppressing leakage current and interfacial polarization, thus the generation of large E b . Therefore, with the Δ S config increases from 0.98 R to 1.44 R, a giant energy storage density ( W rec ) of 8.11 J/cm 3 as well as a high efficiency ( η ) of 90.2 % are synchronously obtained. Significantly, the optimum sample shows outstanding dielectric temperature stability (Δ C / C 25°C ≤ ± 15 %, −55 ∼ 165 °C) in accordance with X8R. This work demonstrates that the medium entropy superparaelectrics are a shortcut to achieve next-generation ceramic capacitors with high comprehensive performance.
研究领域:
材料科学
·
电子工程
✓ 已验证
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2024
·Vol. 50
·期 12
·21859-21868
·
IF 5.1
Haiyan Guo,Kuibao Zhang,Yuxiang Li
In this work, the irradiation response of A 2 Ti 2 O 7 (A represents rare earth elements of Gd, Dy, Ho, Er, Yb and Nd) series ceramics were systematically studied under 3 MeV Au 2+ ions. The structural changes pre- and post-irradiation were characterized using X-ray diffraction (XRD), grazing incidence X-ray diffraction (GIXRD) and Raman spectroscopy . After heavy ion irradiation , all the samples undergo structural transformations from ordered pyrochlore to disordered fluorite and then to amorphous phase. The sample surface became fully amorphous when exposed to the maximum irradiation dose. The 5RETO high-entropy pyrochlore exhibits the lowest rate of amorphization during the process of structural transformation. The cation radius ratio and mixed entropy are the primary factors influencing amorphization rate. The cation radius ratio shows a strong positive correlation with the amorphization rate, while the mixed entropy demonstrates a weak negative correlation with the amorphization rate. The cation radius ratio can thus serve as a reliable indicator for predicting the radiation resistance of high-entropy pyrochlore ceramics.
研究领域:
材料科学
·
核材料
·
固态化学
·
辐射效应
·
无机非金属材料
✓ 已验证
DOI
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2024
·
IF 5.8
Wenchao Lin,Pengrong Ren,Yuhui Wan,Shu Yang
BaTiO 3 , Ba(Ti 0.2 Zr 0.2 Sn 0.2 Hf 0.2 Nb 0.2 )O 3 , SrTiO 3 , Sr(Ti 0.2 Zr 0.2 Sn 0.2 Hf 0.2 Nb 0.2 )O 3 , (Sr 0.5 Ba 0.5 )TiO 3 and (Sr 0.5 Ba 0.5 )(Ti 0.2 Zr 0.2 Sn 0.2 Hf 0.2 Nb 0.2 )O 3 ceramic samples were prepared using a traditional solid-state reaction method. XRD analysis shows that all the samples are a single-phase perovskite structure. After the addition of B-site high-entropy components Sn 4+ , Zr 4+ , Hf 4+ , and Nb 5+ in BaTiO 3 , the permittivity and dielectric loss decrease significantly, and the temperature stability of the permittivity is remarkably improved. Compared with the undoped sample, the insulation resistance of the high-entropy ceramic sample increases exponentially. The incorporation of high entropy components changes the conduction mechanism, improves the insulation performance, and significantly decreases thermal conductivity, which improves the adiabatic performance of ceramics. These results demonstrate that the high entropy strategy can significantly influence the electrical and thermal properties of BaTiO 3 and SrTiO 3 -based ceramics. Our work provides a new idea for the modification of functional ceramic materials and offers new promising candidates of dielectrics applied for Class-I type ceramic capacitors.
研究领域:
材料科学
·
电子工程
✓ 已验证
产品关联
DOI
高影响因子
INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
·
2025
·
IF 8.5
Yang Wang,Huan Wang,Chuanyu Yan,Weitao Wang,Bingzheng Jia,Yiting Yao,Lan Chen,Qilu Hu,Zhimin Xue
To develop a green solvent for lignin dissolution, the most fundamental aspects of its mechanism must be elucidated. Understanding the thermodynamic behaviors is of significant importance for designing novel deep eutectic solvents (DESs) to dissolve lignin. Herein, the heat of dissolution of lignin in acidic, alkaline or neutral DESs was determined by high-precision solution microcalorimetry, and comprehensively investigated the effect of physicochemical properties of DESs on the heat of dissolution and solubility of lignin. The resulted observed that lignin dissolution in alkaline DESs was more vigorous exothermic than that in acidic and neutral DESs. The thermodynamic parameters for the dissolution of lignin in the DESs were calculated from the heat of dissolution and solubility. The positive free energy change indicated that the process of lignin dissolution was non-spontaneous and unfavorable thermodynamically. By analyzing the changes of enthalpy and entropy of lignin solution systematically, lignin dissolution in DESs was enthalpically favorable and controlled by the entropy term. Especially, the interaction entropy predominantly made the free energy change unfavorable for lignin dissolution. The achieved thermodynamic findings could serve as the basis to construct robust DESs for lignin biorefinery.
研究领域:
化学工程
·
生物质科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
ADVANCED MATERIALS
·
2024
·Vol. 36
·期 31
·2400911
·
IF 27.4
Hongxiang Chen,Jiantao Fu,Shuxian Huang,Yiding Qiu,Enhui Zhao,Shiyu Li,Jianeng Huang,Pinqiang Dai,Hengzhong Fan,Bing Xiao
Entropy engineering is widely proven to be effective in achieving ultra-low thermal conductivity for well-performed thermoelectric and heat management applications. However, no strong correlation between entropy and lattice thermal conductivity is found until now, and the fine-tuning of thermal conductivity continuously via entropy-engineering in a wide entropy range is still lacking. Here, a series of high-entropy layered semiconductors, Ni 1− x (Fe 0.25 Co 0.25 Mn 0.25 Zn 0.25 ) x PS 3 , where 0 ≤ x < 1, with low mass/size disorder is designed. High-purity samples with mixing configuration entropy of metal atomic site in a wide range of 0–1.61 R are achieved. Umklapp phonon-phonon scattering is found to be the dominating phonon scattering mechanism, as revealed by the linear T −1 dependence of thermal conductivity. Meanwhile, fine tuning of the lattice thermal conductivity via continuous entropy engineering at metal atomic sites is achieved, in an almost linear dependence in middle-/high- entropy range. Moreover, the slope of the κ - T −1 curve reduces with the increase in entropy, and a linear response of the reduced Grüneisen parameter is revealed. This work provides an entropy engineering strategy by choosing multiple metal elements with low mass/size disorder to achieve the fine tuning of the lattice thermal conductivity and the anharmonic effect.
研究领域:
材料科学
·
热电学
·
固体物理
·
声子工程
✓ 已验证
DOI
高影响因子
Nature Communications
·
2024
·Vol. 15
·期 1
·1-11
·
IF 14.7
Zeng Weihao,Xia Fanjie,Wang Juan,Yang Jinlong,Peng Haoyang,Shu Wei,Li Quan,Wang Hong,Wang Guan,Mu Shichun,Wu Jinsong
Fast-charging, non-aqueous lithium-based batteries are desired for practical applications. In this regard, LiMn 2 O 4 is considered an appealing positive electrode active material because of its favourable ionic diffusivity due to the presence of three-dimensional Li-ion diffusion channels. However, LiMn 2 O 4 exhibits inadequate rate capabilities and rapid structural degradation at high currents. To circumvent these issues, here we introduce quintuple low-valence cations to increase the entropy of LiMn 2 O 4 . As a result, the entropy-increased LiMn 2 O 4 -based material, i.e., LiMn 1.9 Cu 0.02 Mg 0.02 Fe 0.02 Zn 0.02 Ni 0.02 O 4 , when tested in non-aqueous lithium metal coin cell configuration, enable 1000 cell cycles at 1.48 A g −1 (corresponding to a cell charging time of 4 minutes) and 25°C with a discharge capacity retention of about 80%. We demonstrate that the increased entropy in LiMn 2 O 4 leads to an increase in the disordering of dopant cations and a contracted local structure, where the enlarged LiO 4 space and enhanced Mn-O covalency improve the Li-ion transport and stabilize the diffusion channels. We also prove that stress caused by cycling at a high cell state of charge is relieved through elastic deformation via a solid-solution transition, thus avoiding structural degradation upon prolonged cycling.
研究领域:
材料科学
·
电化学
✓ 已验证
DOI
高影响因子
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