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Cuprate-like electronic structures in infinite-layer nickelates with substantial hole dopings

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National science Review 2024年第8期11卷 180-186页

作者： Xiang Ding Yu Fan Xiaoxiao Wang Chihao Li Zhitong An Jiahao Ye Shenglin Tang Minyinan Lei Xingtian Sun Nan Guo Zhihui Chen Suppanut Sangphet Yilin Wang Haichao Xu Rui Peng Donglai Feng Advanced Materials Laboratory State Key Laboratory of Surface Physics and Department of Physics Fudan University School of Emerging technology University of Science and Technology of China New Cornerstone science Laboratory University of Science and Technology of China Shanghai Research Center for Quantum sciences National Synchrotron Radiation Laboratory and School of Nuclear science and technology University of Science and Technology of China

Superconducting infinite-layer（IL） nickelates offer a new platform for investigating the long-standing problem of high-temperature *** models were proposed to understand the superconducting mechanism of nickelates based on the calculated ele ctronic structure,and the multiple Fermi surfaces and multiple orbitals involved create complications and controversial *** the past five years,the lack of direct measurements of the electronic structure has hindered the understanding of nickelate *** we fill this gap by directly resolving the electronic structures of the parent compound LaNiO2and superconducting La0.8Ca0.2NiO2using angle-resolved photoemission *** find that their Fermi surfaces consist of a quasi-2D hole pocket and a 3D electron pocket at the Brillouin zone corner,whose volumes change upon Ca *** Fermi surface topology and band dispersion of the hole pocket closely resemble those observed in hole-doped ***,the cuprate-like band exhibits significantly higher hole doping in superconducting La0.8Ca0.2NiO2compared to superconducting cuprates,highlighting the disparities in the electronic states of the superconducting *** observations highlight the novel aspects of the IL nickelates,and pave the way toward the microscopic understanding of the IL nickelate family and its superconductivity.

关键词： unconventional superconductivity nickelate superconductors oxide MBE ARPES electronic structure superconducting phase diagram

Effect of Al2O3np on the Properties and Microstructure of B4Cp/Al Composites

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Journal of Wuhan University of technology(Materials science) 2020年第3期35卷 514-519页

作者： LIU Tingting PANG Xiaoxuan XIAN Yajiang LUO Hao ZHANG Pengcheng Institute of Materials China Academy Engineering PhysicsMianyang 621907China science and technology on surface physics and Chemistry Laboratory Mianyang 621700China

Aluminum-matrix boron carbide (B4Cp/Al) is a kind of neutron absorbing material widely used in nuclear spent fuel storage. In order to improve the tensile property of B4Cp/Al composites, a new type of nano-Al2O3 particle (Al2O3np) reinforced B4Cp/Al + Al2O3np composites were prepared by powder metallurgy method. The Monte Carlo particle transport program (MCNP) was used to determine the influence of Al2O3np on the thermal neutron absorptivity of composites. The universal material testing machine and scanning electron microscope (SEM) were used to study the mechanical properties, microstructure and fracture morphology of B4Cp/Al composites. The results indicated that the neutron absorption properties of B4Cp/Al composites were not affected by the addition of nano-Al2O3 particles in the range of 1 wt%-15 wt%. The addition of Al2O3np can obviously reduce the grain size of B4Cp/Al matrix metals thus improve the tensile strength of the composites. The addition threshold of Al2O3np is about 2.5 wt%. Both B4Cp and Al2O3np change the fracture characteristics of the composites from toughness to brittleness, and the latter is more important.

关键词： B4Cp/Al composites nano-Al2O3 particles properties microstructure

Dry Sliding Tribological Properties of a Dendrite-reinforced Zr-based Bulk Metallic Glass Matrix Composite

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Journal of Materials science & technology 2014年第6期30卷 576-583页

作者： Huijun Yang Yong Liu Teng Zhang Hengpeng Wang Bin Tang Junwei Qiao Research Institute of surface Engineering Taiyuan University of Technology Laboratory of Applied physics and Mechanics of Advanced Materials College of Materials Science and Engineering Taiyuan University of Technology

In-situ dendrite-reinforced metallic glass matrix （MGM） composites with the composition of Zr58.5Ti14.3Nb5.2Cu6.1Ni4.9Be11.0 were prepared with a vacuum arc melter by the copper mold suction casting. Effect of different normal loads and sliding velocities on the tribological properties of MGM composites was studied. The results showed that the friction coefficient and wear rate of composites initially descended with increasing the normal load and reached a minimum of 0.339 and 1.826 × 10^-4 mm^3/（N m） at 10 N, respectively, then ascended. Similarly, the friction coefficient and wear rate of composites initially decreased with the increase in the sliding velocity and reached a minimum of 0.330 and 2.389 × 10^-4 mm^3/（N m） at 0.4 m/s and 0.3 m/s, respectively, then raised. The wear mechanism of composites was mainly adhesive wear accompanied by abrasive wear at lower normal load and sliding velocity. However, the wear mechanism of composites was abrasive wear and adhesive wear as well as delamination at higher normal load and sliding velocity due to the nucleation and propagation of surface and subsurface cracks during the wear process. The flake-like and particle-like wear debris was the dominant shapes of debris observed.

关键词： Sliding wear Sliding friction surface topography surface analysis Wear testing

A modified multi-group model of angular and momentum distribution of cosmic ray muons for thickness measurement and material discrimination of slabs

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Nuclear science and Techniques 2018年第2期29卷 111-117页

作者： Sa Xiao Wei-Bo He Ming-Cong Lan Ying Chen Mao-Bing Shuai Institute of Materials China Academy of Engineering PhysicsJiangyou 621907China science and technology on surface physics and Chemistry Laboratory Mianyang 621900China

Muon tomography is a capable imaging technique to measure the geometry of high-Z objects. However,most existed algorithms used in muon tomography have obscured the effects of angular distribution and momentum spectra of cosmic ray muons and reduced the spatial resolution. We present a modified multi-group model that takes into account these effects and calibrates the model by the material of lead. Performance tests establish that the model is capable of measuring the thickness of a Pb slab and identifying the material of an unknown slab on a reasonable exposure timescale, in both cases of complete and incomplete angular data. Results show that the modified multi-group model is helpful for improvements in image resolution in real applications.

关键词： Muon tomography Modified multi-group model Angular distribution Momentum spectra

High-efficiency nonlocal reflection-type vortex beam generation based on bound states in the continuum

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National science Review 2023年第5期10卷 201-207页

作者： Tongyu Li Jiajun Wang Wenjie Zhang Xinhao Wang Wenzhe Liu Lei Shi Jian Zi State Key Laboratory of surface physics Key Laboratory of Micro-and Nano-Photonic Structures (Ministry of Education) and Department of PhysicsFudan University Department of physics The Hong Kong University of Science and Technology

Momentum-space polarization vortices centered at symmetry-protected bound states in the continuum of a periodic structure,*** crystal slab,provide a novel nonlocal approach to generate vortex *** approach enjoys a great convenience of no precise alignment requirements,although the generation efficiency of the nonlocal generators requires further optimization before the practical *** this work,we propose a temporal-coupled-mode-theory-based guideline for high-efficiency nonlocal reflection-type vortex generator *** conversion efficiency of the vortex beam is found to be limited by the ratio of the radiative loss to the intrinsic absorption in practical *** increase this ratio through mode selection and structure design,the photonic crystal slabs are theoretically designed and experimentally characterized,showing a maximum on-resonance conversion efficiency of up to 86%.Combining high efficiency with simple fabrication and no re quirement for precise alignment,reflection-type photonic crystal slabs could offer a new and competitive way to generate vortex beams flexibly.

关键词： photonic crystal slab vortex beam bound states in the continuum

Self-propagating high-temperature synthesis of ZrO_2 incorporated Gd_2Ti_2O_7 pyrochlore

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Journal of Advanced Ceramics 2018年第1期7卷 41-49页

作者： Le PENG Kuibao ZHANG Zongsheng HE Dan YIN Jiali XUE Chen XU Haibin ZHANG State Key Laboratory Cultivation Base for Nonmetal Composite and Functional Materials Southwest University of Science and Technology science and technology on surface physics and Chemistry Laboratory China Academy of Engineering Physics Institute of Nuclear physics and Chemistry China Academy of Engineering Physics

In this research, Zr-doped Gd_2Ti_2O_7 pyrochlores, with the composition of Gd_2(Ti_(1-x)Zr_x)_2O_7, were firstly synthesized by self-propagating high-temperature synthesis plus quick pressing(SHS/QP) using CuO as the oxidant and Ti as the reductant. To improve the radiation resistance of titanate–pyrochlore, up to 35 at% Zr was incorporated to substitute the Ti site of Gd_2Ti_2O_7 pyrochlore(Gd_2(Ti_(0.75)Zr_(0.35))_2O_7). XRD and SEM microstructural characterizations showed the formation of a composite ceramic with the major pyrochlore phase and the minor Cu phase. The generated temperature of samples decreased from 1702to 1011 ℃ with increasing Zr content. The effects of sintering temperature and pressure time on phase composition and microstructure were systematically studied. Besides, the influence of thermal transmission on the whole combustion process was also explored. The pyrochlore-based waste form possessed high bulk density of 6.25 g/cm^3 and Vickers hardness of 10.81 GPa. The MCC-1 leaching test showed the normalized elemental leaching rates(42d) of Cu, Gd, and Zr are 1.27×10^(-2), 1.33×10^(-3), and 8.44×10^(-7)g·m^(-2)·d^(-1), respectively.

关键词： self-propagating high-temperature synthesis plus quick pressing (SHS/QP) pyrochlore thermal transmission waste form aqueous leachability

Can Nano-Particle Melt below the Melting Temperature of Its Free surface Partner?

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Communications in Theoretical physics 2015年第2期63卷 249-254页

作者：眭晓红王宗国康凯覃绍京王垂林 State Key Laboratory of Theoretical physics Institute of Theoretical Physics Chinese Academy of Sciences Computer Network Information Center Chinese Academy of Sciences science and technology on surface physics and Chemistry Laboratory China Center of Advanced science and technology

The phonon thermal contribution to the melting temperature of nano-particles is inspected. The discrete summation of phonon states and its corresponding integration form as an approximation for a nano-particle or for a bulk system have been analyzed. The discrete phonon energy levels of pure size effect and the wave-vector shifts of boundary conditions are investigated in detail. Unlike in macroscopic thermodynamics, the integration volume of zero-mode of phonon for a nano-particle is not zero, and it plays an important role in pure size effect and boundary condition effect. We find that a nano-particle will have a rising melting temperature due to purely finite size effect; a lower melting temperature bound exists for a nano-particle in various environments, and the melting temperature of a nano-particle with free boundary condition reaches this lower bound. We suggest an easy procedure to estimation the melting temperature, in which the zero-mode contribution will be excluded, and only several bulk quantities will be used as input. We would like to emphasize that the quantum effect of discrete energy levels in nano-particles, which is not present in early thermodynamic studies on finite size corrections to melting temperature in small systems, should be included in future researches.

关键词： nano-particle quantum size effect boundary condition effect size-dependent melting

High-entropy sulfurization enables efficient non-noble metal-based NiCoFeCuS electrocatalyst for alkaline oxygen evolution reaction

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Particuology 2024年第10期93卷 180-185页

作者： Pan Yang Mengxiang Sun Jingchuan Wang Jinfeng Li Ruizhu Yang Yawei Hao Li Qi Lijun Yang Xue Liu Institute of Materials China Academy of Engineering PhysicsJiangyou621908China State Key Laboratory of Metastable Materials science and technology Yanshan UniversityQinhuangdao066004China science and technology on surface physics and Chemistry Laboratory Jiangyou621907China

Highly active and cost-effective oxygen evolution reaction electrocatalysts have become essential to replace commercial electrocatalysts that rely on rare noble ***-entropy sulfide nanomaterials,characterized by abundant randomly distributed elements and inherent stability,possess significant potential for ***,challenges such as uneven composition,partial oxidation,or imprecise synthesis control still remain in the materials ***,a simple and effective two-step hydrothermal method was employed to synthesize NiCoFeCuS nanoparticles supported on foam nickel *** the catalytic active sites produced by electron density redistribution in high-entropy and sulfurization,NiCoFeCuS exhibits excellent alkaline OER performance,with an overpotential of 261 mV and a Tafel slope of 57.97 mV dec^(−1) at the current density of 10 mA cm^(−2),which is only 88%of commercial RuO_(2) without any noble metals.

关键词： High-entropy Sulfurization NiCoFeCuS electrocatalyst Oxygen evolution reaction Overpotentials

Heteronuclear intermolecular single-quantum coherences in liquid nuclear magnetic resonance

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Chinese physics B 2008年第3期17卷 915-920页

作者：陈松朱小钦蔡淑惠陈忠 Department of physics State Key Laboratory of Physical Chemistry of Solid SurfaceXiamen University School of physics and Optoelectronics technology Key Laboratory of Optoelectronic Science and Technology for MedicineMinistry of EducationFujian Normal University

This paper analyses the heteronuclear Cosy Revamped by Asymmetric Z-gradient Echo Detection pulse sequence. General theoretical expressions of the pulse sequence with arbitrary flip angles were derived by using dipolar field treatment and signals originating from heteronuclear intermolecular single-quantum coherences （iSQCs） in highly-polarized two spin-1/2 systems were mainly discussed in order to find the optimal flip angles. The results show that signals from heteronuclear iSQCs decay slower than those from intermolecular double-quantum coherences or intermolecular zero-quantum coherences. Magical angle experiments validate that the signals are from heteronuclear iSQCs and insensitive to the imperfection of radio-frequency flip angles. All experimental observations are in excellent agreement with theoretical predictions. The quantum-mechanical treatment leads to similar predictions to the dipolar field treatment.

关键词： nuclear magnetic resonance heteronuclear multiple-quantum coherences distant dipolar field highly-polarized system