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Effect of order–disorder transition on thermodynamic and electronic properties of σ and χ phases in W–Re alloy: the first-principles calculation

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Tungsten 2025年第1期7卷 195-213页

作者： Zhi-Peng Zhu Dian Jia William Yi Wang Jun-Lei Yin Xing-Yu Gao Shu-Feng Yang Hai-Feng Song Jin-Shan Li state key laboratory of Solidification Processing Northwestern Polytechnical University laboratory of Computational physics Institute of Applied Physics and Computational Mathematics School of Metallurgical and Ecological Engineering University of Science and Technology Beijing

The Tungsten-Rhenium(W-Re) alloys,celebrated for their high melting point,strength at elevated temperatures,electrical resistivity,and radiation resistance,have been widely utilized in high-temperature components,aerospace,electronics,and nuclear *** constituents of the topologically close-packed(TCP) phases,the sigma phase(σ) and chi phase(χ) formed within W-Re alloys wield considerable influence on the mechanical properties and the stability of the *** calculations were utilized in the present work to explore the structural,thermodynamic,and electronic properties of both ordered and disordered configurations within the σ and χ phases,culminating in a systematic elucidation of the higher phase stability exhibited by the ordered *** is found that the bulk modulus of these two phases is directly proportional to the concentration of Re in the alloy,while the equilibrium volume is inversely *** thermodynamic parameters of the σ and χ phases are calculated via the mean-field potential *** similar trends observed in the isobaric heat capacity,enthalpy increment,and entropy change curves for these two phases suggest they possess comparable thermodynamic *** is noteworthy that the contribution of ionic vibrations predominantly affects the isobaric heat capacity,while the contribution of thermal electronic excitations increases linearly with *** the structure and thermodynamic properties of TCP phases in W-Re alloys at low temperatures has profound significance for optimizing material performance,microstructures features,establishing theoretical foundations,and predicting material behavior.

关键词： First-principles calculations Phase stability TCP phases Thermodynamic properties W–Re alloy

Three-dimensional fracture of UO2 ceramic pellets by phase field modeling

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science China(physics,Mechanics & Astronomy) 2025年第1期Mechanics & Astronomy) .卷 169-180页

作者： Wei Xiong Xuan Ye Hongzhang Cheng Xiaoming Liu institute of nuclear and New Energy technology Collaborative Innovation Center of Advanced Nuclear Energy Technology Key Laboratory of Advanced Reactor Engineering and Safety of Ministry of Education Tsinghua University state key laboratory of Nonlinear Mechanics Institute of Mechanics Chinese Academy of Sciences School of Engineering science University of Chinese Academy of Sciences

Fracture is the primary failure type for the UO2ceramic pellets,which are operated under irradiation and thermal processes,and physically confined by the *** this work,by combining closely coupled physical processes of heat conduction,heat transfer,and mechanical deformation with the cohesive phase field framework,we proposed a high-precision modeling of quasistatic cracking of three-dimensional （3D） UO2ceramic fuel pellets under high temperature and *** simulation results agree well with the experimental results,indicating that the proposed method has the potential to capture 3D crack modes in the interested time ***,we studied the relation of the 3D fracture patterns of fuel pellets with the peak power *** was found that the power level plays a critical role in determining the competition between radial and circumferential cracks,as well as transverse penetrating cracks.

关键词： phase field method nuclear fuel pellet coupled thermo-mechanical model thermal fracture

Applications of in-situ solid-state nuclear magnetic resonance in methanol to olefins reaction

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science China Chemistry 2025年第1期68卷 134-151页

作者： Jing Niu Shutao Xu Yingxu Wei Zhongmin Liu National Engineering Research Center of Lower-Carbon Catalysis technology Dalian Institute of Chemical PhysicsChinese Academy of Sciences state key laboratory of Catalysis Dalian Institute of Chemical Physics Chinese Academy of Sciences University of Chinese Academy of sciences

The methanol-to-olefins（MTO） reaction offers an alternative pathway for the production of low-carbon olefins from non-oil feedstocks. Fundamental research has been impeded by a lack of comprehensive understanding of its underlying mechanism,despite the significant progress made in industry. In-situ solid-state nuclear magnetic resonance（ss NMR） spectroscopy has emerged as a pivotal tool, offering crucial insights into key species under real-time operando conditions. Furthermore, the host–guest interaction between zeolites or surface species residing on zeolites and the reactant/active intermediates is revealed by the combination of in-situ13C MAS NMR and 2D correlation spectroscopy. Moreover, recent technological advancements in hyperpolarization（HP） methods, including HP129Xe NMR and dynamic nuclear polarization（DNP）, have significantly improved the sensitivity of ss NMR, enabling detailed structural and kinetic analysis as well as the detection of trace species. In this feature article, we summarized recent advancements in（in-situ） ss NMR spectroscopy applied to MTO reaction processes,encompassing mechanistic investigations at various stages and the intricate host–guest interactions. These theoretical insights into the dynamic evolution of MTO reactions lay a solid foundation for the optimization of catalytic processes and the development of efficient catalysts, thereby advancing the techniques towards more sustainable and economical production route for olefins.

关键词： MTO zeolites in-situ ssNMR reactive intermediates reaction mechanism

A surface engineering strategy for the stabilization of zinc metal anodes with montmorillonite layers toward long-life rechargeable aqueous zinc ion batteries

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Journal of Energy Chemistry 2025年第1期100卷 94-105页

作者： Wenbo Wang Ruifeng Xu Xu Zhang Peiyu Wang Bao Yang Bingjun Yang Juan Yang Kailimai Su Pengjun Ma Yanan Deng Xianfeng Fan Wanjun Chen key laboratory for Electronic Materials College of Electrical Engineering Northwest Minzu University Resource Chemistry and Energy Materials Research Center State Key Laboratory of Solid Lubrication Lanzhou Institute of Chemical Physics Chinese Academy of Sciences University of Chinese Academy of Sciences institute for Materials and Processes School of Engineering University of Edinburgh

Rechargeable aqueous zinc-ion batteries （AZIBs） exhibit appreciable potential in the domain of electrochemical energy ***,there are serious challenges for AZIBs,for instance zinc dendrite growth,hydrogen evolution reaction （HER）,and corrosion side ***,we propose a surface engineering modification strategy for coating the montmorillonite （MMT） layer onto the surface of the Zn anode to tackle these issues,thereby achieving high cycling stability for rechargeable *** results reveal that the MMT layer on the surface of the Zn anode is able to provide ordered zincophilic channels for zinc ions migration,facilitating the reaction kinetics of zinc *** functional theory（DFT） calculations and water contact angle （CA） tests prove that MMT@Zn anode exhibits superior adsorption capacity for Zn2+and better hydrophobicity than the bare Zn anode,thereby achieving excellent cycling ***,the MMT@Zn||MMT@Zn symmetric cell holds the stable cycling over 5600 h at 0.5 mA cm-2and 0.125 m A h cm-2,even exceeding 1800 h long cycling under harsh conditions of 5 m A cm-2and 1.25 m A h *** MMT@Zn||V2O5full cell reaches over 3000 cycles at 2 A g-1with excellent rate ***,this surface engineering modification strategy for enhancing the electrochemical performance of AZIBs represents a promising application.

关键词： Hydrogen evolution reaction

Plasma parameter diagnosis using hydrogen emission spectra of a quartz-chamber 2.45 GHz ECRIS at Peking University

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science China(physics,Mechanics & Astronomy) 2018年第4期61卷 69-74页

作者： WenBin Wu HaiTao Ren ShiXiang Peng Yuan Xu JiaMei Wen Tao Zhang JingFeng Zhang AiLin Zhang Jiang Sun ZhiYu Guo JiaEr Chen state key laboratory of nuclear physics and technology & institute of heavy ion physics Peking University

A quartz-chamber 2.45 GHz electron cyclotron resonance ion source(ECRIS) was designed for diagnostic purposes at Peking University [Patent Number: ZL 201110026605.4]. This ion source can produce a maximum 84 m A hydrogen ion beam at 50 k V with a duty factor of 10%. The root-mean-square(RMS) emittance of this beam is less than 0.12π mm mrad. In our initial work,the electron temperature and electron density inside the plasma chamber had been measured with the line intensity ratio of noble gases. Based on these results, the atomic and molecular emission spectra of hydrogen were applied to determine the dissociation degree of hydrogen and the vibrational temperature of hydrogen molecules in the ground state, respectively. Measurements were performed at gas pressures from 4×10^(-4) to 1×10^(-3) Pa and at input peak RF power ranging from 1000 to 1800 W. The dissociation degree of hydrogen in the range of 0.5%-10% and the vibrational temperature of hydrogen molecules in the ground state in the range of 3500-8500 K were obtained. The plasma processes inside this ECRIS chamber were discussed based on these results.

关键词： electron cyclotron resonance ion source(ECRIS) hydrogen plasma optical emission spectroscopy dissociation degree of hydrogen vibrational temperature

A fast emittance measurement unit for high intensity DC beam

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Chinese physics B 2018年第2期27卷 446-449页

作者：张艾霖任海涛彭士香张滔徐源张景丰温佳美武文斌郭之虞陈佳洱 state key laboratory of nuclear science and technology & institute of heavy ion physics School of Physics Peking University

A combined unit, which has the ability to measure the current and emittance of the high intensity direct current（DC）ion beam, is developed at Peking University（PKU）. It is a multi-slit single-wire（MSSW）-type beam emittance meter combined with a water-cooled Faraday Cup, named high intensity beam emittance measurement unit-6（HIBEMU-6）. It takes about 15 seconds to complete one measurement of the beam current and its emittance. The emittance of a 50-mA@50-kV DC proton beam is measured.

关键词： emittance measurement high intensity DC beam MSSW

Successful Nitrogen Doping of 1.3 GHz Single Cell Superconducting Radio-Frequency Cavities

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Chinese physics Letters 2018年第3期35卷 75-78页

作者：陈术郝建奎林林朱凤冯立文王芳谢华木郭鑫陈蒙全胜文刘克新 state key laboratory of nuclear physics and technology & institute of heavy ion physics Peking University

A high intrinsic quality factor （Q0） of a superconducting radio-frequency cavity is beneficial to reducing the oper- ation costs of superconducting accelerators. Nitrogen doping （N-doping） has been demonstrated as a aseful way to improve Q0 of the superconducting cavity in recent years. N-doping researches with 1.3 GHz single cell cavities are carried out at Peking University and the preliminary results are promising. Our recipe is slightly different from other laboratories. After 250μm polishing, high pressure rinsing and 3 h high temperature annealing, the cavities are nitrogen doped at 2.7-4.0Pa for 20rain and then followed by 15μm electropolishing. Vertical test results show that Q0 of a 1.3 GHz single cell cavity made of large grain niobium has increased to 4 ×10 10 at 2.0K and medium gradient.

关键词： Successful Nitrogen Doping of 1.3 GHz Single Cell Superconducting Radio-Frequency Cavities BCP BCS Figure

Mechanism and enhancement of photoluminescence from silicon nanocrystals implanted in SiO_2 matrix

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Chinese physics B 2010年第9期19卷 617-621页

作者：吴志永刘克新任晓堂 state key laboratory of nuclear physics and technology Institute of Heavy Ion PhysicsPeking University

Photoluminescence （PL） spectra of Si nanocrystals （NCs） prepared by 130 keV Si ions implantation onto SiO2 matrix were investigated as a function of annealing temperature and implanted ion dose. PL spectra consist of two PL peaks, originated from smaller Si NCs due to quantum confinement effect （QCE） and the interface states located at the surface of larger Si NCs. The evolution of number of dangling bonds （DBs） on Si NCs was also investigated. For bydrogen-passivated samples, a monotonic increase in PL peak intensity with the dose of implanted Si ions up to 3× 10^17 ions/cm^2 is observed. The number of DBs on individual Si NC, the interaction between DBs at the surface of neighbouring Si NCs and their effects on the efficiency of PL are discussed.

关键词： ion implantation nanocrystals photoluminescence dangling bond

Relative enhancement of photoluminescence intensity of passivated silicon nanocrystals in a silicon dioxide matrix

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Chinese physics B 2012年第9期21卷 509-513页

作者：吴志永刘克新任晓堂 state key laboratory of nuclear physics and technology Institute of Heavy Ion PhysicsPeking University

Photoluminescence （PL） intensity of passivated silicon nanocrystals （Si NCs） embedded in a SiO2 matrix is com- pared with that of unpassivated Si NCs. We investigate the relative enhancement of PL intensity （IR） as a function of annealing temperature and implanted Si ion dose. The IR increases simultaneously with the annealing temperature. This demonstrates an increase in the number of dangling bonds （DBs） with the degree of Si crystallization varying via the annealing temperature. The increase in IR with implanted Si ion dose is also observed. We believe that the near-field interaction between DBs and neighboring Si NCs is an additional factor that reduces the PL efficiency of unpassivated Si NCs.

关键词： ion implantation nanocrystals photoluminescence dangling bond