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Superconductivity 2024年第2期10卷 29-37页

作者： Shermane M.Benjamin The National High Magnetic Field Laboratory 1800 E.Paul Dirac DriveTallahasseeFL 32310USA

Superconductivity is a phenomenon arising from cooperative electron ***,correlations among(1)the minimum tuning parameter required for emergence,(2)the superconducting transition temperature resulting from minimal tuning,and(3)the host’s physical/chemical properties still elude the scientific *** empirical investigations,such as those revealing ideal gas-like correlations at the onset of superconductivity in intercalated superconductors,motivate this *** investigation reports similar findings in systems(>170 compounds)exhibiting superconductivity through other perturbative means,such as single-element *** general,statistical measures,including distance correlation analyses(≠linear regression fit)of thermodynamic variables,indicate the presence of empirical relationships near the superconducting onset of systematically tuned *** relations involve unit cell volume(V),the number of valence electrons(N),and the superconducting transition temperature(T_(c)).Note:The author’s primary aim is not to validate or challenge BCS theory;it is instead to focus on leveraging methodology led by available data to enhance the exploration and development of innovative and cost-effective superconductors.

关键词： Superconductivity Ideal gas law Empirical Doping Intercalation Critical pressure Phenomenological theory Predicting T_(c)

Second-order phase correction of NMR spectra acquired using linear frequency-sweeps

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Magnetic Resonance Letters 2022年第1期2卷 1-8,I0002页

作者： Zhehong Gan Ivan Hung National High Magnetic Field Laboratory 1800 East Paul Dirac DriveTallahasseeFL32310USA

NMR spectra acquired with experiments using frequency-sweeps such as the wide-band uniform-rate smooth truncation(WURST)spin-echo and Carr-Purcell-Meiboom-Gill(CPMG)sequences cannot be absorptively phased by using only conventional zerothand first-order phase *** of phase correction up to the secondorder is described for obtaining absorptive spectra,which have more desirable line shapes and noise properties than magnitude *** relationship of the second-order phase to the parameters of frequency sweeps is *** second-order phasing in the frequency-domain is equivalent to a point spread in the time-domain *** application of second-order phase correction is demonstrated with a wideline 35Cl CPMG spikelet spectrum.

关键词： Second-order phase Noise Line shape Absorptive Dispersive Frequency sweep CHIRP WURST Adiabatic Broadband CPMG Spin-echo Wideline ^(35)Cl

Effect of ceria surface facet on stability and reactivity of isolated platinum atoms

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Nano Research 2022年第7期15卷 5922-5932页

作者： Bochuan Song Shuxin Si Asiye Soleymani Yan Xin Helena E.Hagelin-Weaver Department of Chemical Engineering University of FloridaGainesville 32611USA National High Magnetic Field Laboratory Florida State UniversityTallahassee 32310USA

Well-defined surface structures and uniformity are key factors in exploring structure–activity relationships in heterogeneous catalysts.A modified atomic layer deposition method and three well-defined CeO_(2) nanoshapes,octahedra with(111)surfaces,cubes exposing(100)facets,and rods with(100)and(110)surface facet terminations,were utilized to synthesize ultra-low loading Pt/CeO_(2) catalysts and allow investigations on the influence of ceria surface facet on isolated Pt species under reducing conditions.A mild reduction temperature(150℃)reduces the initial platinum ions present on the surfaces of the ceria support but preserves the isolated Pt atoms on all ceria surface *** contrast,a reduction temperature of 350°C,reveals very different interactions between the initial single Pt atoms and the various ceria surface facets,leading to dissimilar and nonuniform Pt ensembles on the three ceria *** isolate facet dependent Pt–CeO_(2) interactions and avoid variations between Pt species,the Pt1/CeO_(2) catalysts after reduction at 150°C were subjected to CO oxidation *** isolated Pt atoms on the CeO_(2) octahedra and cubes are less active in the CO oxidation reaction,compared with Pt on CeO_(2) *** the case of Pt on the CeO_(2) octahedra this is due to strongly bound CO blocking active sites together with a stable CeO_(2)(111)surface limiting the oxygen supply from the *** the CeO_(2) cubes,some Pt is not available for reaction and CO is bound strongly on the available Pt *** addition,the Pt catalysts supported on the CeO_(2) cubes are not stable with time on *** isolated Pt atoms on the CeO_(2) rods are considerably more active under these conditions and this is due to a weaker Pt–CO bond strength and more facile reverse oxygen spillover from the defect-rich(110)surfaces of the rods due to the lower energy of oxygen vacancy formation on this CeO_(2) *** Pt supported on the CeO_(2) rods is also remarkably stable with t

关键词： single atom catalyst CeO_(2)shapes facet effects Pt1/CeO_(2) diffuse reflectance infrared Fourier transform spectroscopy(DRIFTS)

40-meter-long REBCO tapes with critical current over 4,000 A/12 mm at 4.2 K and 13 T by advanced MOCVD

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Superconductivity 2024年第1期9卷 29-34页

作者： Mahesh Paidpilli Chirag Goel Bhabesh Sarangi Siwei Chen Eduard Galstyan Jan Jaroszynski Griffin Bradford Dmytro Abraimov Venkat Selvamanickam Department of Mechanical Engineering Advanced Manufacturing InstituteTexas Center for SuperconductivityUniversity of HoustonHoustonTexasUSA AMPeers LLC HoustonTexasUSA National High Magnetic Field Laboratory TallahasseeFloridaUSA

REBa_(2)Cu_(3)O_(7−δ)(REBCO,RE=rare earth)tapes doped with 5%and 15%Zr have been scaled up to lengths more than 40 m in a pilot‐scale advanced metal organic chemical vapor deposition(A‐MOCVD)*** precursor compositions used for the long tapes were guided by a study of the influence of(Ba+dopant)/Cu content on the critical current density(Jc)of 5 and 15 mol.%Hf‐and Zr‐added tapes at 4.2 K and 13 *** 40‐mlong tapes exhibited a critical current(Ic)over 4,000 A/12 mm at 4.2 K and 13 T as well as over 1,400 A/12 mm at 20 K and 20 *** critical current densities of a 40‐m‐long tape doped with 5%Zr at 4.2 K measured at the National High Magnetic Field Laboratory(NHMFL)were>10 MAcm^(−2)and>5 MAcm^(−2)at 14 T and 30 T,respectively,which are over three times those of commercial REBCO *** infield Jc of 5%Zradded 40‐m‐long tapes was similar to those of previously‐reported high‐performance short samples made with 15%Zr or *** results demonstrate the excellent potential of A‐MOCVD for manufacturing high Ic REBCO tapes for use in ultrahigh‐field magnet applications.

关键词： High‐temperature superconductors MOCVD REBCO Critical current

Suppression of discontinuous precipitation and strength improvement by Sc doping in Cu-6 wt%Ag alloys

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Journal of Materials Science & Technology 2023年第4期135卷 80-96页

作者： Bailing An Rongmei Niu Yan Xin William LStarch Zhaolong Xiang Yifeng Su Robert E.Goddard Jun Lu Theo M.Siegrist Engang Wang Ke Han Key Laboratory of Electromagnetic Processing of Materials(Ministry of Education) Northeastern UniversityShenyang 110819China School of Materials Science and Engineering Northeastern UniversityShenyang 110819China School of Metallurgy Northeastern UniversityShenyang 110819China National High Magnetic Field Laboratory Florida State UniversityTallahasseeFL 32310USA Oak Ridge National Laboratory Oak RidgeTN 37830USA FAMU-FSU College of Engineering TallahasseeFL 32310USA

In low-Ag Cu matrix alloys,the presence of coarse discontinuous precipitates may limit *** demonstrated that discontinuous precipitation was suppressed,and continuous precipitation was en-hanced by the doping of Cu-6 wt%Ag with Sc.A high-volume fraction of continuous precipitates,which nucleated on{111}planes,led to a 55 MPa increase in strength,with only a slight decrease in electri-cal *** addition of Sc inhibited the nucleation of discontinuous precipitates by causing the Sc and the Ag to co-segregate onto grain boundaries,thus forming a thin intermetallic compound layer between *** deformation,both discontinuous and continuous precipitates were drawn into Ag *** combination of deformation strain and doping caused an increase in density and a decrease in the diameter of Ag fibers,resulting in about 205 MPa increase in doped samples when the deformation strain reached *** thinner,denser Ag fibers in the doped samples also caused higher electron scatter-ing at interfaces,leading to electrical conductivity that was 11%IACS lower than in non-doped *** reference,100%IACS(International Annealed Copper Standard)is equivalent to 1.7241μΩcm.

关键词： Sc doping Grain boundary segregation Precipitation Strength Electrical conductivity Plastic deformation

On the use of cross polarization in solid-state NMR:1 H spinlock versus adiabatic demagnetization in the rotating frame

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Magnetic Resonance Letters 2022年第3期2卷 147-158页

作者： Yuchen Li Shengyu Zhang Ze Wu Xinhua Peng Riqiang Fu CAS Key Laboratory of Microscale Magnetic Resonance and School of Physical Sciences University of Science and Technology of ChinaHefei230026China CAS Center for Excellence in Quantum Information and Quantum Physics University of Science and Technology of ChinaHefei230026China Hefei National Laboratory Hefei230088China National High Magnetic Field Laboratory 1800 East Paul Dirac DriveTallahasseeFL32310USA

Cross polarization(CP)is a widely used solid-state nuclear magnetic resonance(NMR)technique for enhancing the polarization of dilute S spins from much larger polarization of abundant I spins such as 1 *** achieve such a polarization transfer,the I spin should either be spin-locked or be converted to the dipolar ordered state through adiabatic demagnetization in the rotating *** this work,we analyze the spin dynamics of the Hartmann-Hahn CP(HHCP)utilizing the 1 H spin-locking,and the dipolar-order CP(DOCP)having the 1 H adiabatic *** further propose an adiabatic demagnetization CP(ADCP)where a constant radio-frequency pulse is applied on the S spin while 1 H is adiabatically *** analyses indicate that ADCP utilizes the adiabatic passage to effectively achieve the polarization transfer from the 1 H to S *** addition,the dipolar ordered state generated during the 1 H demagnetization process could also be converted into the observable S polarization through DOCP,further enhancing the polarized *** is shown by both static and magic-angle-spinning(MAS)NMR experiments that ADCP has dramatically broadened the CP matching condition over the other CP *** samples have been used to demonstrate the polarization transfer efficiency of this newly proposed ADCP scheme.

关键词： Cross polarization Spin-lock in rotating frame Adiabatic demagnetization Spin dynamics Dipolar ordered state Solid-state NMR

Detecting water-protein chemical exchange in membrane- bound proteins/peptides by solid-state NMR spectroscopy--Dedicated to Professor Xiuwen Han on the occasion of her 80th birthday

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Magnetic Resonance Letters 2021年第2期1卷 99-111页

作者： Rongfu Zhang Timothy A.Cross Riqiang Fu National High Magnetic Field Laboratory 1800 East Paul Dirac DriveTallahasseeFL32310USA Department of Chemistry and Biochemistry Florida State UniversityTallahasseeFL32301USA

Water plays an important role in many essential biological processes of membrane proteins in hydrated lipid *** general,the 1H polarization transfers berween water molecules and site--specific protons in proteins can be classified as coherent(via dipolar spin diffusion)and incoherent(via chemical exchange and nuclear Overhauser effect)***-state NMR is the technique of choice for studying such water-protein interactions in membrane-bound proteins/peptides through the detection of'H polarization transfers from water to the *** polarization transfer mechanisms often exist simultaneously and are difficult to quantify ***,we review water-protein polarization transfer techniques in solid state NMR with a focus on the recent progress for the direct detection of site-specific kinetic water-protein chemical exchange processes on the sub-millisecond time scale in membrane-bound *** measurements of the pure chemical exchange ki-netics provide a unique opportunity to understand the role that water plays in the structure-function relationships of membrane bound species at the water-bilayer *** addi-tion,the perspective of chemical exchange saturation transfer(CEST)experiments in membrane-bound proteins/peptides is further discussed.

关键词： Chemical exchange Spin diffusion HETCOR CEST Water-protein interactions Solid-state NMR

Manipulation of Molecular Qubits by Isotope Effect on Spin Dynamics

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CCS Chemistry 2021年第9期3卷 2548-2556页

作者： Jing Li Shi-Jie Xiong Chun Li Biaobing Jin Yi-Quan Zhang Shang-Da Jiang Zhong-Wen Ouyang Zhenxing Wang Xing-Long Wu Johan van Tol You Song State Key Laboratory of Coordination Chemistry School of Chemistry and Chemical EngineeringNanjing UniversityNanjing 210023 National Laboratory of Solid State Microstructures Department of PhysicsNanjing UniversityNanjing 210093 Research Institute of Superconductor Electronics(RISE) School of Electronic Science and EngineeringNanjing UniversityNanjing 210093 Jiangsu Key Laboratory for NSLSCS School of Physical Science and TechnologyNanjing Normal UniversityNanjing 210023 National Laboratory for Molecular Sciences State Key Laboratory of Rare Earth Materials Chemistry and ApplicationsBeijing Key Laboratory for Magnetoelectric Materials and DevicesCollege of Chemistry and Molecular EngineeringPeking UniversityBeijing 100871 Wuhan National High Magnetic Field Center&School of Physics Huazhong University of Science and TechnologyWuhan 430074 National High Magnetic Field Laboratory Florida State UniversityTallahasseeFL 32310

Controlling spin behavior via external stimuli is a key route to develop molecular spintronics ***,temperature,pressure,chemicals,and electric field are the possible ***,we report a new method,the isotope effect,to control spin behavior in molecule magnet *** can not only control the relaxation of magnetization,but also regulate the spin lifetime of quantum coherence.

关键词： molecule-based magnetism molecular qubits isotope effect spin–vibration coupling quantum coherence

Intrinsic and Extrinsic Exciton Recombination Pathways in AgInS_(2)Colloidal Nanocrystals

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Energy Material Advances 2021年第1期2021卷 165-174页

作者： Matteo L.Zaffalon Valerio Pinchetti Andrea Camellini Sergey Vikulov Chiara Capitani Bing Bai Meng Xu Francesco Meinardi Jiatao Zhang Liberato Manna Margherita Zavelani-Rossi Scott A.Crooker Sergio Brovelli Dipartimento di Scienza dei Materiali Universitàdegli studi di Milano-Bicoccavia Roberto Cozzi 5520125 MilanoItaly Dipartimento di Energia Politecnico di MilanoVia Ponzio 34/320133 MilanoItaly Istituto Italiano di Tecnologia Via Morego 3016163 GenovaItaly Glass to Power SpA Via Fortunato Zeni 838068 RoveretoItaly Beijing Key Laboratory of Construction-Tailorable Advanced Functional Materials and Green Applications School of Materials Science&EngineeringBeijing Institute of TechnologyBeijing 100081China IFN-CNR Piazza Leonardo da Vinci 3220133 MilanoItaly National High Magnetic Field Laboratory Los Alamos National LaboratoryLos AlamosNew Mexico 87545USA

Ternary I-III-VI2 nanocrystals(NCs),such as AgInS_(2) and CuInS_(2),are garnering interest as heavy-metal-free materials for photovoltaics,luminescent solar concentrators,LEDs,and *** origin of the emission and absorption properties in this class of NCs is still a subject of *** theoretical and experimental studies revealed that the characteristic Stokesshifted and long-lived luminescence of stoichiometric CuInS_(2) NCs arises from the detailed structure of the valence band featuring two sublevels with different *** same valence band substructure is predicted to occur in AgInS_(2) NCs,yet no experimental confirmation is available to ***,we use complementary spectroscopic,spectro-electrochemical,and magneto-optical investigations as a function of temperature to investigate the band structure and the excitonic recombination mechanisms in stoichiometric AgInS_(2) *** transmission measurements reveal the signatures of two subbands with opposite parity,and photoluminescence studies at cryogenic temperatures evidence a dark state emission due to enhanced exchange interaction,consistent with the behavior of stoichiometric CuInS_(2) *** the temperature as well as applying reducing electrochemical potentials further suppress electron trapping,which represents the main nonradiative channel for exciton decay,leading to nearly 100%emission efficiency.

关键词： parity valence applying

Intrinsic Photoconductivity of Few-layered ZrS2 Phototransistors via Multiterminal Measurements

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Semiconductor Science and Information Devices 2019年第2期1卷 19-28页

作者： Rukshan M.Tanthirige Carlos Garcia Saikat Ghosh Frederick Jackson II Jawnaye Nash Daniel Rosenmann Ralu Divan Liliana Stan Anirudha V.Sumant Stephen A.McGill Paresh C.ay Nihar R.Pradhan Layered Materials and Device Physics Laboratory Department of ChemistryPhysics and Atmospheric ScienceJackson State UniversityJacksonMS 39217USA National High Magnetic Field Laboratory TallahasseeFL 32310USA Kunming University of Science and Technology Kunming 650500China Center for Nanoscale Materials Argonne National Laboratory9700 S-Cass AvenueLemontIL-60439USA

We report intrinsic photoconductivity studies on one of the least examined layered compounds,***-atomic layer ZrS2 field-effect transistors were fabricated on the Si/SiO2 substrate and photoconductivity measurements were performed using both two-and four-terminal configurations under the illumination of 532 nm laser *** measured photocurrent as a function of the incident optical power at several source-drain(bias)*** observe a significantly large photoconductivity when measured in the multiterminal(four-terminal)configuration compared to that in the two-terminal *** an incident optical power of 90 nW,the estimated photosensitivity and the external quantum efficiency(EQE)measured in two-terminal configuration are 0.5 A/W and 120%,respectively,under a bias voltage of 650 *** the same conditions,the four-terminal measurements result in much higher values for both the photoresponsivity(R)and EQE to 6 A/W and 1400%,*** significant improvement in photoresponsivity and EQE in the four-terminal configuration may have been influenced by the reduction of contact resistance at the metal-semiconductor interface,which greatly impacts the carrier mobility of low conducting *** suggests that photoconductivity measurements performed through the two-terminal configuration in previous studies on ZrS2 and other 2D materials have severely underestimated the true intrinsic properties of transition metal dichalcogenides and their remarkable potential for optoelectronic applications.

关键词： Field-effect transistors Zirconium sulphide Phototransistor Responsivity Quantum efficiency