检索结果-南通市图书馆

Improving the Solidified Structure by Optimization of Coil Configuration in Pulsed Magneto-Oscillation

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2018年第12期31卷 1334-1344页

作者： Jing Zhao Ji-Hao Yu Ke Han Hong-Gang Zhong Ren-Xing Li Qi-Jie Zhai Department of Mechanical and Electrical Engineering Tangshan University State Key laboratory of Advanced Special Steel Shanghai University National high magnetic Field laboratory Florida State University

Using both numerical and experimental methods, we studied the effect of coil configuration of pulsed magneto-oscillation（PMO） on distribution of electromagnetic field, flow field and solidification structure with the same pulse currentparameters in A1 ingots. We designed and constructed three types of coils： surface pulsed magneto-oscillation, hot-toppulsed magneto-oscillation （HPMO） and combined pulsed magneto-oscillation （CPMO）. PMO treatment refined thesolidification structure in all the ingots. The configuration of the PMO, however, introduced differences in magnetic fieldintensity, electromagnetic force, Joule heat, flow field, equiaxed grain zone, grain size and growth direction of columnargrains. The largest equiaxed grain zone was found in CPMO treated ingot, and the smallest grain size was found in bothHPM0 and CPMO treated ingots. Numerical simulation indicated that difference in electromagnetic field and flow fieldresulted in differences in solidification structure. HPMO is more advantageous over others for large ingot production.

关键词： Pulsed magneto-oscillation Coil configuration Electromagnetic field Flow field Solidification structure Optimization

Spin correlations in the S = 1 armchair chain Ni_(2)NbBO_(6) as seen from NMR

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2021年第4期30卷 512-517页

作者： Kai-Yue Zeng Long Ma Long-Meng Xu Zhao-Ming Tian Lang-Sheng Ling Li Pi Anhui Province Key laboratory of Condensed Matter Physics at Extreme Conditions High Magnetic Field LaboratoryChinese Academy of SciencesHefei 230031China Hefei National laboratory for Physical Sciences at the Microscale University of Science and Technology of ChinaHefei 230026China School of Physics and Wuhan National high magnetic Field Center Huazhong University of Science and TechnologyWuhan 430074China

We report our nuclear magnetic resonance(NMR) study on the structurally spin chain compound Ni_(2)NbBO_(6) with complex magnetic *** antiferromagnetic transition is monitored by the line splitting resulting from the staggered internal hyperfine *** magnetic coupling configuration proposed by the first-principle density functional theory(DFT) is supported by NMR spectral *** the spin dynamics,a prominent peak at T~35 K well above the Neel temperature(T_(N)~20 K at μ0 H=10 T) is observed from the spin-lattice relaxation *** compared with the dc-susceptibility,this behavior indicates an antiferromagnetic coupling with the typical energy scale of ~3 ***,the Ni_(2)NbBO_(6) compound can be viewed as strongly ferromagnetically coupled armchair spin chains along the crystalline *** facts place strong constraints on the theoretical model for this compound.

关键词： low-dimensional quantum magnetism magnetic coupling spin excitations nuclear magnetic resonance

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

在线全文

学校读者我要写书评

暂无评论

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)

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

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

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

Modulation of Insulator-Metal Transition Temperature by Visible Light in La7/8Sr1/8MnO3 Thin Film

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 2010年第9期27卷 207-210页

作者：胡令孙玉平王波罗轩盛志高朱雪斌宋文海杨昭荣戴建明 Key laboratory of Materials Physics Institute of Solid State Physics Chinese Academy of Sciences Hefei 230031 high magnetic Field laboratory Chinese Academy of Sciences Hefei 230031

Effects of magnetic field and light illumination on the electrical transport properties of La7/8Sr1/8MnO3 thin film grown on a Si substrate are investigated. The film shows an insulator-metal transition at Tp - 191.9 K and a low-temperature resistance minimum at Tmin ≈ 48 K in darkness. Both magnetic field and light illumination shift the insulator-metal transition temperature Tp to be higher, while the low-temperature transport properties of the film induced by them show different trends. That is, the magnetic field and light illumination make the Tmin shift to lower and higher temperatures, respectively. The enhancement of both Tp and Train under light illumination could be explained in terms of photoinduced hole-doping and demagnetization effects of La7 /8Sr1/8MnO3.

关键词： METAL-insulator transitions TRANSITION temperature THIN films magnetic fields MAGNETIZATION TRANSPORT theory (Mathematics)

Simulation of time bunching for a pulsed positron beam

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics B 2008年第11期17卷 4149-4152页

作者：高传波熊涛郗传英翁惠民叶邦角韩荣典周先意 Department of Modern Physics University of Science and Technology of China high magnetic Field laboratory Hefei Institutes of Physical Science Chinese Academy of Sciences

Simulate anneal arithmetic has been used to settle the problem of time bunching on a pulsed slow-positron beam device. This paper has searched for the parameters of the device in a large scope and achieved the time re... 详细信息

关键词： pulsed positron beam time resolution simulate anneal arithmetic

Pressure-induced anomalous insulating behavior in frustrated iridate La_(3)Ir_(3)O_(11)

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2021年第6期30卷 547-551页

作者： Chun-Hua Chen Yong-Hui Zhou Ying Zhou Yi-Fang Yuan Chao An Xu-Liang Chen Zhao-Ming Tian Zhao-Rong Yang Anhui Province Key laboratory of Condensed Matter Physics at Extreme Conditions High Magnetic Field LaboratoryChinese Academy of SciencesHefei 230031China Science Island Branch of Graduate School University of Science and Technology of ChinaHefei 230026China Institutes of Physical Science and Information Technology Anhui UniversityHefei 230601China School of Physics and Wuhan National High Magnetic Field CenterHuazhong University of Science and TechnologyWuhan 430074China high magnetic Field laboratory of Anhui Province Hefei 230031China

The geometrically frustrated iridate La_(3)Ir_(3)O_(11) with strong spin–orbit coupling and fractional valence was recently predicted to be a quantum spin liquid candidate at ambient conditions. Here, we systematically investigate the evolution of structural and electronic properties of La_(3)Ir_(3)O_(11) under high pressure. Electrical transport measurements reveal an abnormal insulating behavior rather than metallization above a critical pressure P_(c) ~ 38.7 GPa. Synchrotron x-ray diffraction(XRD)experiments indicate the stability of the pristine cubic KSbO_(3)-type structure up to 73.1 GPa. Nevertheless, when the pressure gradually increases across P_(c), the bulk modulus gets enhanced and the pressure dependence of bond length d_(Ir-Ir) undergoes a slope change. Consistent with the XRD data, detailed analyses of Raman spectra reveal an abnormal redshift of Raman mode and a change of Raman intensity around P_(c). Our results demonstrate that the pressure-induced insulating behavior in La_(3)Ir_(3)O_(11) can be assigned to the structural modification, such as the distortion of IrO_6 octahedra. These findings will shed light on the emergent abnormal insulating behavior in other 5 d iridates reported recently.

关键词： high pressure 5d iridates semimetal–insulator transition crystal structure

Excellent soft magnetic properties realized in FeCoN thin films

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2012年第3期21卷 428-431页

作者：张璐然吕华刘曦白建民魏福林 Key laboratory of Education Ministry on Magnetism and magnetic Material Research Institute of Magnetic MaterialsLanzhou University

FeCoN soft magnetic thin films are prepared by using the reactive direct-current magnetron sputtering technique. It is found that the addition of N2 can reduce the coercivity of the FeCoN film, and excellent soft magnetic properties can be obtained when the ratio of N2 flow to total gas flow is 10%. The influences of texture, grain size, and stress on the magnetic properties and the high-frequency behaviors of the films are also discussed.

关键词： nanocrystalline soft magnetic material magnetic thin films iron alloys

Superconductivity, electronic phase diagram, and pressure effect in Sr_(1-x)Pr_xFBiS_2

在线全文

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2019年第5期62卷 99-106页

作者： Wei You Lin Li HaiYang Yang JiaLu Wang HongYing Mao Li Zhang ChuanYing Xi Jie Cheng YongKang Luo JianHui Dai YuKe Li Department of Physics and Hangzhou Key laboratory of Quantum Matter Hangzhou Normal University Department of Physics China Jiliang University high magnetic Field laboratory Chinese Academy of Sciences College of Science Center of Advanced Functional Ceramics Nanjing University of Posts and Telecommunications Wuhan National high magnetic Field Center School of Physics Huazhong University of Science and Technology

Based on a combination of X-ray diffraction, electrical transports, magnetic susceptibility, specific heat, and pressure-effect measurements, we report the results of experiments on a series of BiS_2-based Sr_(1-x)Pr_xFBiS_2 superconductors with the maximum Tcof 2.7 K for x=0.5 and at ambient pressure. Superconductivity appears only for 0.4≤x≤0.7 whereas the normal-state resistivity shows the semiconducting-like behaviors. The magnetic susceptibility χ(T) displays the low superconducting shielding volume fractions and C(T) shows no distinguishable anomaly near Tc, which suggests a filamentary superconductivity in the Pr-doped polycrystalline samples. By varying doping concentrations, an electronic phase diagram is established. Upon applying pressure on the optimally doped Sr_(0.5)Pr_(0.5)FBiS_2 system, Tcis abruptly enhanced, reaches 8.5 K at the critical pressure of P_c=1.5 GPa, and increases slightly to 9.7 K at 2.5 GPa. Accompanied by the enhancement of superconductivity from the low-to the high-Tc phases, the normal state undergoes a semiconductor-to-metal transition when under pressure. This scenario may be linked to enhanced overlap of the Bi-6 p and S-p orbitals, which contributes to the enhanced superconductivity above Pc. The pressuretemperature phase diagram for Sr_(0.5)Pr_(0.5)FBiS_2 is also presented.

关键词： BiS2-based superconductors superconductivity phase diagram pressure effect