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Enabling highly efficient and broadband electromagnetic wave absorption by tuning impedance match in high-entropy transition metal diborides (HETMB_(2))

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Journal of advanced Ceramics 2021年第6期10卷 1299-1316页

作者： Weiming ZHANG Fu-Zhi DAI Huimin XIANG Biao ZHAO Xiaohui WANG Na NI Rajamallu KARRE Shijiang WU Yanchun ZHOU Science and Technology on Advanced Functional Composite Laboratory Aerospace Research Institute of Materials&Processing TechnologyBeijing 100076China Henan Key Laboratory of Aeronautical Materials and Application Technology School of Material Science and EngineeringZhengzhou University of AeronauticsZhengzhou 450046China Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China Key Lab of Education Ministry for Power Machinery and Engineering School of Mechanical EngineeringShanghai Jiao Tong UniversityShanghai 200240China Zibo Firststar New Material Incorporated Co. Ltd.Zibo 255000China

The advance in communication technology has triggered worldwide concern on electromagnetic wave *** cope with this challenge,exploring high-performance electromagnetic(EM)wave absorbing materials with dielectric and magnetic losses coupling is urgently *** the EM wave absorbers,transition metal diborides(TMB2)possess excellent dielectric loss ***,akin to other single dielectric materials,poor impedance match leads to inferior ***-entropy engineering is expected to be effective in tailoring the balance between dielectric and magnetic losses through compositional ***,three HE TMB2 powders with nominal equimolar TM including HE TMB2-I(TM=Zr,Hf,Nb,Ta),HE TMB2-2(TM=Ti,Zr,Hf,Nb,Ta),and HE TMB2-3(TM=Cr,Zr,Hf,Nb,Ta)have been designed and prepared by one-step boro/carbothermal *** a result of synergistic effects of strong attenuation capability and impedance match,HE TMB2-1 shows much improved performance with the optimal minimum reflection loss(RL_(min))of-59.6 dB(8.48 GHz,2.68 mm)and effective absorption bandwidth(EAB)of 7.6 GHz(2.3 mm).Most impressively,incorporating Cr in HE TMB2-3 greatly improves the impedance match over 1-18 GHz,thus achieving the RLmin of-56.2 dB(8.48 GHz,2.63 mm)and the EAB of 11.0 GHz(2.2 mm),which is superior to most other EM wave absorbing *** work reveals that constructing high-entropy compounds,especially by incorporating magnetic elements,is effectual in tailoring the impedance match for highly conductive compounds,i.e.,tuning electrical conductivity and boosting magnetic loss to realize highly efficient and broadband EM wave absorption with dielectric and magnetic coupling in single-phase materials.

关键词： transition metal diboride(TMB2) high-entropy(HE)ceramics electronic structure microwave absorption dielectric and magnetic losses coupling

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Microstructure modification and corrosion resistance enhancement of die-cast Mg-Al-Re alloy by Sr alloying

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Journal of Magnesium and Alloys 2021年第3期9卷 950-963页

作者： Matthew S.Dargusch Zhiming Shi Hanliang Zhu Andrej Atrens Guang-Ling Song The University of Queensland Centre for Advanced Materials Processing and Manufacturing(AMPAM)School of Mechanical and Mining EngineeringBrisbaneQLD 4072Australia Australian Nuclear Science&Technology Organisation Locked Bag 2001Kirrawee DCSydneyNSW 2232Australia The University of Queensland Materials EngineeringSchool of Mechanical and Mining EngineeringBrisbaneQld 4072Australia State Key Lab for Physical Chemistry of Solid State Surfaces Center for Marine Materials Corrosion and ProtectionCollege of MaterialsXiamen UniversityXiamenFujian 361005China

The effects of Sr additions on the microstructure and corrosion performance of a Mg-Al-RE alloy in 3.5 wt.%Na Cl saturated with Mg(OH)_(2) have been *** examination reveals that the Sr addition introduces additional intermetallic phases,refines intermetallic networks and dendritic grains,and improves the network *** Al and rare earth elements can be identified in the intermetallics and grain boundaries or inter-dendrite regions under a transmission electron microscope and secondary electron microscope,*** the Sr-containing intermetallic phases and the refined microstructure,the oxide films become more protective,resulting in more corrosion resistant boundary areas and thus dendrite grain ***,the presence of large amounts of intermetallics and boundaries can enhance the corrosion performance of the Mg-Al-RE alloy containing Sr.

关键词： A.magnesium B.TEM B.SEM C.segregation C.Alkaline corrosion

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Enhancing the Long-Term Stability of Photoresponse in Mgzno Based Uv Msm Photodetector Using Pdms Polymer Capping

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SSRN 2023年

作者： Chetia, Shantanu Kaushik Das, Amit K. Ajimsha, Rohini Sreedharan Mahapatra, Abhinav Singh, Rashmi Misra, Pankaj Oxide Nano-Electronics Lab. Laser Materials Processing Division Raja Ramanna Centre for Advanced Technology Indore452 013 India Homi Bhabha National Institute Training School Complex Anushakti Nagar Mumbai400 085 India Laser & Functional Materials Division Raja Ramanna Centre for Advanced Technology Indore452 013 India

The diffusion of ambient oxygen into MgxZn1-xO based photodetectors (PDs) changes the photoresponse characteristics of the devices over time and, thus, is an issue of a critical concern for their practical application. In this report, the effects of ambient exposure on the long term photoresponse properties of ITO/Mg0.22Zn0.88O/ITO PDs have been studied and a method to improve the stability has been introduced using a polydimethylsiloxane (PDMS) capping layer as a protective barrier against oxygen diffusion. The peak responsivity of the PDs without PDMS capping layer increases from 2.2 mA/W to ~ 69.4 mA/W and the dark current increased from ~ 5.4 × 10-10 to 1.1 × 10-9 in 40 days of ambient exposure, while the peak responsivity and the dark current of the device with PDMS capping remains practically unchanged over time. Additionally, the device with PDMS capping layer demonstrated faster photocurrent rise and decay time as compared to the device without PDMS capping. This finding demonstrates the efficacy of the PDMS capping layer in preserving the photoresponse characteristics of MgxZn1-xO based UV PDs, thereby enhancing their long-term stability. This research not only advances our understanding of the stability issues in MgxZn1-xO based PDs but also paves the way for their successful integration into various photodetection applications. © 2023, The Authors. All rights reserved.

关键词： Photodetectors

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Al2o3 Barrier Layer for Enhancing Uv to Visible Rejection Ratio in P-Si/N-Mgzno Heterojunction Visible Blind Uv Photodetectors

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SSRN 2023年

作者： Chetia, Shantanu Kaushik Das, Amit Kumar Ajimsha, Rohini Sreedharan Singh, Rashmi Padhi, P.S. Misra, Pankaj Oxide Nano-Electronics Lab. Laser Materials Processing Division Raja Ramanna Centre for Advanced Technology Indore452 013 India Homi Bhabha National Institute Training School Complex Anushakti Nagar Mumbai400 085 India Laser and Functional Materials Division Raja Ramanna Centre for Advanced Technology Indore452 013 India

The fabrication of visible blind ultraviolet photodetectors based on p-Si/n-MgxZn1-xO heterojunction is challenging due to the generation of visible photoresponse caused by the drift of visible light generated electrons from p-silicon to n-MgxZn1-xO across the interface. Here, it is shown that by incorporating a thin Al2O3 interlayer at the heterojunction, the UV-to-visible rejection ratio in p-Si/n-MgxZn1-xO photodetectors can be significantly enhanced. The Al2O3 interlayer inserted between n-MgxZn1-xO and p-Si serves as an effective blocking layer against the transport of visible light-generated electrons from p-Si to n-MgxZn1-xO, thereby suppressing the visible photoresponse. As a result, the UV-to-visible rejection ratio improved by roughly three orders of magnitude. This high degree of visible blindness of p-Si/n-MgxZn1-xO heterojunction photodetectors with an Al2O3 barrier layer holds great promise for next-generation visible-blind UV photodetection applications based on p-Si/n-MgxZn1-xO heterojunctions. © 2023, The Authors. All rights reserved.

关键词： Heterojunctions

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Essentially degenerate hidden nodal lines in two-dimensional magnetic layer groups

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Physical Review B 2024年第23期110卷 235163-235163页

作者： Xiao-Ping Li Chaoxi Cui Lei Wang Weikang Wu Zeying Zhang Zhi-Ming Yu Yugui Yao School of Physical Science and Technology Inner Mongolia University Hohhot 010021 China Centre for Quantum Physics Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement (MOE) School of Physics Beijing Institute of Technology Beijing 100081 China Beijing Key Lab of Nanophotonics & Ultrafine Optoelectronic Systems School of Physics Beijing Institute of Technology Beijing 100081 China Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials Ministry of Education Shandong University Jinan 250061 China College of Mathematics and Physics Beijing University of Chemical Technology Beijing 100029 China

According to the theory of group representations, the types of band degeneracy can be divided into accidental degeneracy and essential degeneracy. The essentially degenerate nodal lines (NLs) are typically resided on the high-symmetry lines of the Brillouin zone. Here, we propose a type of NL in two dimensions that is essentially degenerate but is hidden within the high-symmetry planes, making it less observable, dubbed a hidden-essential nodal line (HENL). The existence of HENL is guaranteed as long as the system hosts a horizontal glide-mirror symmetry, hence such NLs can be widely found in both nonmagnetic and magnetic systems. We perform an exhaustive search over all 528 magnetic layer groups (MLGs) for HENL that can be enforced by glide-mirror symmetry with both spinless and spinfull systems. We find that 122 candidate MLGs host spinless HENL, while 63 candidate MLGs demonstrate spinful HENL. In addition, we reveal that horizontal mirror and time-reversal symmetry in type-II and type-IV MLGs with spin-orbital coupling can enforce HENL formed. The 15 corresponding candidate MLGs have also been presented. Furthermore, we derive a few typical lattice models to characterize the existence for the HENL. For specific electronic fillings in real materials, namely 4N+2 in spinless systems (and 2N+1 in spinful systems), the presence of the HENLs in candidate MLGs is required regardless of the details of the systems. Using ab initio calculations, we further identify possible material candidates that realize spinless and spinful HENL. Moreover, spinful HENLs exhibit a persistent spin texture with the characteristic of momentum-independent spin configuration. Our findings uncover a type of topological semimetal state and offer an ideal platform to study the related physics of HENLs.

关键词： Mirrors

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The Enhanced Cohesive Performance of Magnetron Sputtered Cr Coatings on Steel Substrate via Controlling Columnar Grain Structures

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SSRN 2024年

作者： Liu, Wenxin Xu, Zhigang Geng, Xuehao Liu, Long Peng, Jian Shen, Qiang Wang, Chuanbin State Key Lab of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan430070 China Chaozhou Branch Chemistry and Chemical Engineering Guangdong Laboratory Chaozhou521000 China Inner Mongolia North Heavy Industries Group Limited Company Nanjing Institute Nanjing210049 China

Enhancing the cohesion of Cr coatings is essential for preventing cracking and prolonging their durability in service. This study focuses on investigating the impact of columnar grain structures on the cohesive strength of the Cr coating on steel substrate. The systematic variation in deposition time during the magnetron sputtering process significantly affected the columnar grain structures, surface roughness, residual stress, and cohesive strength of Cr coatings. The results revealed that all Cr coatings exhibited preferred orientations along the (211) plane. As the deposition time increased from 1 to 4 h, the columnar grain size and surface roughness of Cr coatings progressively increased, while the residual compressive stress demonstrated a gradual decline. The cohesion strengths of the coating initially rose and then declined. Notably, the columnar grain size of approximately 700 nm achieved the best cohesion for Cr coatings on stainless steel, attributed to the combined effects of residual stress and surface roughness. This study underscores the significance of adjusting coating columnar grain structures to improve cohesion and offers valuable insights for the development of advanced hard coatings. © 2024, The Authors. All rights reserved.

关键词： Surface roughness

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In situ synthesis of a porous high-Mn and high-Al steel by a novel two-step pore-forming technique in vacuum sintering

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Journal of materials Science & technology 2020年第4期39卷 82-88页

作者： Chuanbing Zhuang Zhigang Xu Shangyu Huang Yu Xia Chuanbin Wang Qiang Shen Hubei Key Laboratory of Advanced Technology for Automotive Components Wuhan University of TechnologyWuhan 430070China Hubei Collaborative Innovation Center for Automotive Components Technology Wuhan University of TechnologyWuhan 430070China School of Materials Science and Engineering Wuhan University of TechnologyWuhan 430070China State Key Lab of Advanced Technology for Materials Synthesis and Processing Wuhan University of TechnologyWuhan 430070China Hubei Engineering Research Center for Green Precision Materials Forming Wuhan University of TechnologyWuhan 430070China

In this work, a novel in-situ two-step pore-forming process in vacuum sintering(ITPVS) technique combining low-temperature processing to produce open pores through the interdiffusion among the intrinsic components in the base steel, and subsequent high-temperature processing to further improve the porosities by the sublimation of Mn via previously formed open pores, was proposed to produce a lab.scale porous Fe Mn Al steel. For the first time, a high-Mn and high-Al steel with open and overall porosities of ~59.6 vol.% and ~63.7 vol.%(percent in volume, vol.%) was synthesized by isothermal holding of the quaternary elemental Fe/Mn/Al/C powder mixture at 640℃ for 1 h and the subsequent sintering at 1200℃ for 1 h. Elemental Al partly incorporated into/reacted with α-Fe and α-Mn after sintering at640℃ for 1 h, leading to the overall and open porosities promoting by ~26.6 vol.% and ~25.6 vol.%. After sintering at 1200℃, Fe Mn Al steel with increased porosities mainly comprising of austenite and α-Fe obtained. The compression strength and corresponding strain of the 1200℃-sintered porous specimen without crack on the surface was ~75 MPa and ~25%. The ITPVS technique takes advantage of using the intrinsic components like Al, Mn and Fe in steels to produce porous structure. This is beneficial to avoiding the contamination of the Fe Mn Al steel matrix caused by the employment of the foreign pore-forming agents.

关键词： Porous metal High manganese steel Two-stage sintering Reaction-diffusion Sublimation method

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Impact of normal and inverse spinel structure evolution induced by co-substitution of chemical units on the luminescence properties of Ni2+-Activated Gallium Titanate Phosphor NIR-II

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Ceramics International 2025年

作者： Feng, Tong Liang, Lijia Zhou, Hui Jin, Yuanlin Long, Zhangwen Zhou, Dacheng Jiang, Xiaqing Liu, Bitao Qiu, Jianbei Faculty of Material Science and Engineering Kunming University of Science and Technology Kunming650093 China College of Materials Science and Engineering Institute for New Materials Technology Chongqing University of Arts and Sciences Chongqing402160 China Chongqing Institute of Green and Intelligent Technology Chinese Academy of Sciences Chongqing China Key Lab. of Advanced Materials of Yunnan Province Kunming650093 China Southwest United Graduate School Kunming650092 China The First People's Hospital of Yunnan Province Yunnan Kunming China

The rapid advancement of near-infrared light source technology has positioned phosphor-converted light-emitting diodes (PC-LEDs) operating within the near-infrared spectrum at the forefront of interdisciplinary research, with extensive applications in biomedicine, food quality assessment, and agricultural monitoring. However, the development of light sources that cover the second near-infrared spectral window (NIR-II, 1000–1700 nm) continues to encounter significant technical challenges. Inspired by chemical unit co-substitution strategy, we successfully developed a broadband NIR-II phosphor designated as (Li0.7Mg0.3)(Ga0.7Mg0.3)TiO4:0.003Ni2+ ((L0.7M0.3)(G0.7M0.3)T:0.003Ni2+) through [Mg2+-Mg2+] dual-site substitution in orthorhombic LiGaTiO4 (LGT) normal spinel. This co-substitution strategy resulted in an impressive enhancement of the internal quantum efficiency by 29.77 %–64.8 %, while maintaining thermal stability without significant attenuation at elevated temperature. To validate its practical utility, we fabricated prototype for a NIR phosphor-converted LED by integrating (L0.7M0.3)(G0.7M0.3)T:0.003Ni2+ a commercial 340 nm chip. The resulting device demonstrates promising potential for applications in food safety inspection and deep-tissue infrared imaging. This work provides a perspective for designing broadband high-efficiency NIR-II phosphors via modulation of crystal field environment. © 2025

关键词： Near infrared spectroscopy

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Efficient Ba2NaNb5O15:Cr3+,Yb3+ nanocrystals embedded transparent glass-ceramics toward night-vision application

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Ceramics International 2025年

作者： Ji, Wenbo Zhu, Fengmei Gao, Yuan Qiu, Jianbei Faculty of Material Science and Engineering Kunming University of Science and Technology Kunming650093 China Southwest United Graduate School Kunming650092 China Key Lab. of Advanced Materials of Yunnan Province Kunming650093 China

Near-infrared (NIR) spectroscopy has the advantages of instant responsiveness, non-destructiveness and high signal-to-noise ratio, and has broad application prospects in night vision security monitoring, indoor agriculture, biomedical imaging and photodynamic therapy, etc. NIR phosphor-converted light-emitting diodes (NIR pc-LEDs) as a NIR light source, have the advantages of compact size, broadband emission, high efficiency, readily availab.e LED chips as excitation light sources, tunable emission spectrum, and excellent prospects for industrial manufacture. However, the service life of traditional organic packaging materials is greatly reduced over time due to heat accumulation and accelerated aging, especially when operated under high-power irradiation. To overcome this drawback, we successfully prepared Ba2NaNb5O15:Cr3+,Yb3+ nanocrystals embedded in stable and transparent glass-ceramics by a two-stage process that involves an melt-quenching followed by a re-crystallization heat-treatment. Under 460 nm excitation, the glass-ceramics exhibited a 700–1200 nm broadband NIR emission that originated from the Cr3+-activating centers and a sharp line emission near ∼980 nm that originated from the Yb3+-activating centers, with a PLQY was ∼43.7 %. A NIR pc-LED light source device with a direct contact structure between transparent glass-ceramic and a blue chip was prepared, and the application potential of the NIR light source in night-vision imaging was verified. © 2025 Elsevier Ltd and Techna Group S.r.l.

关键词： Fluorescence

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Fabrication of nanoporous Ni and NiO via a dealloying strategy for water oxidation catalysis

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Journal of Energy Chemistry 2020年第11期29卷 125-134页

作者： Xiangrong Ren Yiyue Zhai Qi Zhou Junqing Yan Shengzhong Liu Key Laboratory of Applied Surface and Colloid Chemistry Ministry of EducationShaanxi Engineering Lab for Advanced Energy TechnologySchool of Materials Science and EngineeringShaanxi Normal UniversityXi'an 710119ShaanxiChina State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals Lanzhou University of TechnologyLanzhou 730050GansuChina Materials Science and Engineering College Lanzhou University of TechnologyLanzhou 730050GansuChina

Nickel oxides and(oxy)hydroxides are promising replacements for noble-metal-based catalysts owing to their high activity and good long-term stability for the oxygen evolution reaction(OER). Herein, we developed nanoporous Ni by a method of combined rapid solidification and chemical dealloying. Subsequently,nanoporous Ni O was obtained via heating treatment, the macropore and skeleton sizes of the NiO originated from Ni10Al90 alloy are 100–300 nm and 80–200 nm, respectively. Benefiting from the multi-stage nanoporous structure and high specific surface area, the nanoporous NiO demonstrates an outstanding OER, reaching 20 mA cm-2 at an overpotential of 356 mV in 1 M KOH. The corresponding Tafel slope and apparent activation energy are measured to be 76.73 mV dec-1 and 29.0 kJ mol-1, respectively. Moreover,kinetic analysis indicates that the Ni O catalyst shows pseudocapacitive characteristics, and the improved current is attributed to the high-rate pseudocapacitive behavior that efficiently maintains increased nickel redox cycling to accelerate the reaction rates. After 1000 cycles of voltammetry, the overpotential of the NiO decreases by 22 mV(j = 10 mA cm-2), exhibiting excellent stability and durability.

关键词： Rapid solidification Dealloying Nanoporous Ni Electrocatalyst OER

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