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Upconversion photoluminescence of Er-doped Bi_(4)Ti_(3)O_(12) ceramics enhanced by vacancy clusters revealed by positron annihilation spectroscopy

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Chinese Physics B 2024年第12期33卷 360-366页

作者： Huiru Cheng Yuhuan Li Ziwen Pan Jiandang Liu bangjiao ye State Key Laboratory of Particle Detection and Electronics University of Science and Technology of ChinaHefei 230026China

Doping of rare earth elements into Bi_(4)Ti_(3)O_(12)can significantly enhance the upconversion photoluminescence(UCPL)properties,but its structure-property relationship is still *** this work,Er-doped bismuth titanate Bi_(4-x)Er_(x)Ti_(3)O_(12)(x=0,0.1,0.2,0.3,0.4,0.5)ceramics were synthesized via solid-state reaction *** x-ray diffraction analysis confirmed the orthorhombic crystalline structure of the Bi4-xErxTi3012ceramics without any secondary *** and calculations of positron annihilation spectroscopy were carried out to characterize their defect *** comparison between the experimental and calculated lifetime revealed that vacancy clusters were the main defects in the *** increase of the intensity of the second positron lifetime component(I_(2))of Bi_(3.5)Er_(0.5)Ti_(3)O_(12)ceramics indicated the presence of a high concentration of vacancy *** UCPL spectra showed the sudden enhanced UCPL performance in Bi3.7Er0.3Ti3O12and Bi_(3.5)Er_(0.5)Ti_(3)O_(12)ceramics,which were consistent with the variation of the second positron lifetime component(I2).These results indicate that the enhanced UCPL properties are influenced not only by the concentrations of rare earth ions but also by the concentration of vacancy clusters present within the ceramics.

关键词： bismuth layered structure positron annihilation lifetime spectroscopy upconversion photoluminescence vacancy clusters

Insights into the dual-roles of alloying elements in the growth of Sn whiskers

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Journal of Materials Science & Technology 2022年第22期117卷 65-71页

作者： Yan Zhang Chengjie Lu Yun Dong Min Zhou Jiandang Liu Hongjun Zhang bangjiao ye ZhengMing Sun School of Materials Science and Engineering Southeast UniversityNanjing 211189China State Key Laboratory of Particle Detection and Electronics University of Science and Technology of ChinaHefei 230026China School of Chemistry and Materials Science University of Science and Technology of ChinaHefei 230026China

The growth of Sn whiskers from Ti_(2)SnC/Sn-X(X=Sn,Bi,Pb,Ga)samples was studied in this work to understand the effect of alloying elements on whiskering *** mobility of source Sn atoms relating with the formation and migration of defects was found to be the critical factor dominating the growth rate,with the gathering of which to grow whiskers on the surface acts as an effective means to lower the *** a result,the source Sn atoms would migrate to whisker root spontaneously,making the growth of whiskers the nature of materials,and external factors like compressive stress or oxidation are no more necessary but facilitate the whiskering process by promoting the mobility of source Sn atoms.

关键词： Whisker MAX phase DFT Positron annihilation Defects

Atmospheric CO_(2) capture and photofixation to near-unity CO by Ti^(3+)-V_(o)-Ti^(3+) sites confined in TiO_(2) ultrathin layers

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Science China Chemistry 2021年第6期64卷 953-958页

作者： Liang Liang Peiquan Ling Yuhuan Li Li Li Jiandang Liu Qiquan Luo Hongjun Zhang Qian Xu Yang Pan Junfa Zhu bangjiao ye Yongfu Sun Hefei National Laboratory for Physical Science at Microscale National Synchrotron Radiation LaboratoryUniversity of Science and Technology of ChinaHefei 230026China Institute of Physical Science and Information Technology Anhui UniversityHefei 230601China

To realize efficient atmospheric CO_(2) chemisorption and activation,abundant Ti^(3+) sites and oxygen vacancies in TiO_(2) ultrathin layers were *** annihilation lifetime spectroscopy and theoretical calculations first unveil each oxygen vacancy is associated with the formation of two Ti^(3+)sites,giving a Ti^(3+)-V_(o)-Ti^(3+) *** Ti^(3+)-V_(o)-Ti^(3+) sites could bond with CO_(2) molecules to form a stable configuration,which converted the endoergic chemisorption step to an exoergic process,verified by in-situ Fourier-transform infrared spectra and theoretical ***,the adjacent Ti^(3+)sites not only favor CO_(2) activation into COOH*via forming a stable Ti^(3+)–C–O–Ti^(3+) configuration,but also facilitate the rate-limiting COOH^(*)scission to CO^(*)by reducing the energy barrier from 0.75 to 0.45 e ***,the Ti^(3+)-V_(o)-TiO_(2) ultrathinlayers could directly capture and photofix atmospheric CO_(2) into near-unity CO,with the corresponding CO_(2)-to-CO conversion ratio of ca.20.2%.

关键词： TiO_(2)ultrathin layers CO_(2)activation CO_(2)photofixation positron annihilation lifetime spectroscopy

Characteristics and time resolutions of two CeBr_(3) gamma-ray spectrometers

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Radiation Detection Technology and Methods 2020年第3期4卷 327-336页

作者： Jianguo Qin Caifeng Lai Jun Xiao Xinxin Lu Tonghua Zhu Rong Liu bangjiao ye Institute of Nuclear Physics and Chemistry CAEPP.O.Box 213Mianyang 621900China Department of Modern Physics University of Science and Technology of ChinaHeifei 230026China

Purpose The purpose of this work is to study the pulse shape,energy resolution,non-proportionality of energy response for gamma-rays,and time characteristics of CeBr_(3) *** The time and energy responses of two CeBr_(3) detectors were characterized by an analog method and a digital method using a set of standardγ-ray *** pulse shape,energy resolution and non-proportionality(nPR)of energy response forγ-rays were characterized using the analog *** the analog method,the high voltage applied to PMTs,parameters of walk and external delay of constant fraction discriminator were *** the digital method,a CEAN 1729A digitizer with sampling frequency of 2 GS/s and resolution of 11 bit,and a digital constant fraction discrimination technique were used to study the time performance of the two CeBr_(3) ***,the coincidence time resolutions of the CeBr_(3) detectors for the gamma peaks of ^(22)Na and ^(60)Co were measured using the two *** The t_(rise),lifetimeτ,t_(fall) for CeBr_(3)21^(#)and 22^(#)are 11.2 ns,23.8 ns,50.2 ns,and 10.4 ns,26.5 ns,58.6 ns,*** measured non-proportionality of CeBr_(3)21^(#)and 22^(#)are 1.08%and 2.22%,*** time resolutions of the two CeBr_(3) detectors are 244±2 ps and 248±3 ps at the energy peaks of ^(60)Co source,and 336±2 ps and 335±3 ps at 511 keV for the analog and the digital *** The time resolutions obtained by the analog method and the digital method are almost *** CeBr_(3) detector is a good option in the applications such as half-life measurements,ToF-PET and high counting rate ***,it is a goodγ-ray spectrometer owing to the preferable energy resolution and non-internal activity.

关键词： Cerium bromide CeBr_(3) Time resolution Analog and digital method Non-proportionality

Effect of Defects on Magnetic Properties of O^(+) -implanted AlN Films by Positron Annihilation Spectroscopy

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原子核物理评论 2024年第1期41卷 498-503页

作者： ye Run ye bangjiao School of Physics and Electronic Engineering Yancheng Teachers UniversityYancheng 224007JiangsuChina State Key Laboratory of Particle Detection and Electronics University of Science and Technology of ChinaHefei 230026China

Room-temperature ferromagnetism is observed in the O^(+)-implanted AIN films with O+doses of 5×10^(16) cm^(-2)(AIN:Osxion)and 2×10^(17) cm^(-2)(AIN:O_(2x1on)).The observed magnetic anisotropy indicates that the ferromagnetism is attributed to the intrinsic properties of O^(+) -implanted AIN *** out-of-plane saturation magnetization(Ms)of the AIN:O5×10^(16) is about 0.68 emu/g,much higher than that of AIN:O_(2x1017),0.09 emu/g,which is due to the excessively high O^(+)dose made more O+ions occupy adjacent A1^(3+)positions in forms of antiferromagnetic *** broadening of positron annihilation radiation measurements demonstrate the existence of Al vacancies in the O^(+)-implanted AIN *** first-principles calculations suggest that the ferromagnetism originates mainly from the Al ***,the formation of divacancies or vacancy clusters by high concentrations of Al vacancies will lead to the transformation of VA-VAi coupling from ferromagnetim to antiferromagnetism,ultimately weakening the ferromagnetism of the sample.

关键词： positron annihilation spectroscopy ion implantation semiconductors ferromagnetism

Horizontal oscillation processed large MXene with Low Ti–Ti coordination for fast sodium storage

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Science China Chemistry 2024年第11期67卷 3729-3738页

作者： Hang Wang Xingwu Zhai Yujian Xia Zhixin Sun Tianchen Wei Guangyu Chen Yuhuan Li Xinfeng Tang Liang Wu Zhaodi Fan Hongjun Zhang bangjiao ye Xueyuan Leng Min Zhou Hefei National Laboratory for Physical Sciences at the Microscale School of Chemistry and Materials ScienceUniversity of Science and Technology of ChinaHefei 230026China National Synchrotron Radiation Laboratory University of Science and Technology of ChinaHefei 230029China State Key Laboratory of Particle Detection and Electronics University of Science and Technology of ChinaHefei 230026China School of Aerospace Engineering and Applied Mechanics Tongji UniversityShanghai 200092China

MXene stands out as a rising family of transition metal carbides/nitrides with exceptional size-dependent properties and versatile potential applications. However, the realization of large MXene with a controllable surface at atomic level remains challenging to keep the balance among the conductivity, stability and activity. Herein, the horizontal oscillation-induced delamination(HOD)strategy is proposed to acquire Ti_(3)C_(2) flakes with large size and low Ti–Ti coordination(HO-Ti_(3)C_(2)). The average size of the asobtained flakes can reach 6.48 μm to keep the overall conductive skeleton and merits from large size. Simultaneously, metal atoms at surface can be partially removed due to the enhanced local vibrational turbulence during the reciprocating horizontal oscillation process. Such MXenes with clear and unique surface states exhibit high potentials in ion adsorption together with satisfied electric conductivity and stability. As proof of concept, HO-Ti_(3)C_(2) anode exhibits remarkable rate capability and longterm stability during sodium storage. A capacity of 100.5 m Ah g^(-1)with a long-life cycle(4,500 cycles) at a high rate of 1.0 A g^(-1)originates from the increased s-d interaction between Na and Ti. Therefore, the HOD strategy provides a controllable surface design to promote the clear criteria into size-dependent research on MXene.

关键词： horizontal oscillation induced delamination shear force large flakes coordination environment fast sodium storage

Measurement of Double Differential Cross Section for ^(93)Nb(n,xp) Reaction at E_n=14.6 MeV

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Chinese journal of nuclear physics 1994年第2期16卷 120-126页

作者： ye bangjiao Fan Yangmei Wang Zhongmin Han Rongdian(Department of Modern Physics,University of Science and Technology of China,Hefei 230026)Xiao Zhenxi(Institute of Management,University of Science and Technology of China,Beijing 100080) 中国科学技术大学近代物理系安徽合肥 230026 中国科学技术大学近代物理系安徽合肥中国科学技术大学管理学院北京 100080

-The energy spectrum and angular distributions of protons from 93Nb（n,xp）reactions are measured by means of the USTC（University of Science and Technologyof China）multitelescope *** total proton production cross sections are in fairagreement with the results of other *** energy spectrum is well explained by thesum of the spectra calculated on the basis of the preequilibrium and the H-F *** from the previous measurement at the high energy end of the angle-inte-grated proton spectrum are *** angular distributions which show a stronglyenergy-dependent forward-backward asymmetry are in fair agreement with thephenomenological model of Kalbach-Mann.

关键词： Double differential cross section Neutron induced reaction Preequilibrium

Coordination-driven structure reconstruction in polymer of intrinsic microporosity membranes for efficient propylene/propane separation

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The Innovation 2022年第6期3卷 137-144页

作者： Yanxiong Ren Boyang Chong Wei Xu Zhengqing Zhang Lin Liu Yingzhen Wu Yutao Liu Haifei Jiang Xu Liang Hong Wu Hongjun Zhang bangjiao ye Chongli Zhong Guangwei He Zhongyi Jiang Joint School of National University of Singapore and Tianjin University International Campus of Tianjin UniversityBinhai New CityFuzhou 350207China Key Laboratory for Green Chemical Technology of Ministry of Education School of Chemical Engineering and TechnologyTianjin UniversityTianjin 300072China Chemistry and Chemical Engineering Guangdong Laboratory Shantou 515031China Collaborative Innovation Center of Chemical Science and Engineering(Tianjin) Tianjin 300072China State Key Laboratory of Particle Detection and Electronics University of Science and Technology of ChinaHefei 230026China State Key Laboratory of Separation Membranes and Membrane Processes Tiangong UniversityTianjin 300387China

Polymers of intrinsic microporosity(PIMs),integrating unique microporous structure and solution-processability,are one class of the most promising membrane materials for energy-efficient gas ***,the micropores generated from inefficient chain packing often exhibit wide pore size distribution,making it very challenging to achieve efficient olefin/paraffin ***,we propose a coordination-driven reconstruction(CDR)strategy,where metal ions are incorporated into amidoxime-functionalized PIM-1(AO-PIM)to in situ generate coordination crosslinking *** varying the type and content of metal ions,the resulting crosslinking structures can be optimized,and the molecular sieving capability of PIM membranes can be dramatically ***,the introduction of alkali or alkaline earth metals renders more precise micropores contributing to superior C3H6/C3H8 separation performance.K+incorporated AO-PIM membranes exhibit a high ideal C3H6/C3H8 selectivity of 50,surpassing almost all the reported polymer ***,the coordination crosslinking structure significantly improves the membrane stability under higher pressure as well as the plasticization resistant *** envision that this straightforward and generic CDR strategy could potentially unlock the potentials of PIMs for olefin/paraffin separations and many other challenging gas separations.

关键词： separation porosity crosslinking

F-μbond length andμSR depolarization spectrum calculation for fluoride using two-component density functional theory

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Chinese Physics B 2023年第8期32卷 120-123页

作者：潘智康邓力潘子文原钺张宏俊叶邦角 State Key Laboratory of Particle Detection and Electronics University of Science and Technology of ChinaHefei 230026China

First-principles calculation of muons in ionic fluorides has been proposed ***,there is a considerable difference between the obtained F-μbond length and the experimental data obtained by muon spin relaxation(μSR).Considering that the difference may be caused by ignoring the quantum effect of muons,we use two-component density functional theory(TCDFT)to consider the quantized muon and recalculate the bond length and theμSR depolarization *** testing several muon-electron correlation,we show that TCDFT can give better results than the commonly used“DFT+μ”.

关键词： muon spin relaxation/rotation fluoride density-functional theory