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学者姓名:张久兴
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Abstract :
Samarium hexaboride (SmB6) predicted to be a topological Kondo insulator, is the first strongly correlated heavy fermion material to exhibit topological surface states. In this work, the high quality SmB6 single crystal have been successfully grown by the floating zone method and the electrical transport at low temperature was measured at Oxford Instruments Heliox VL. The results show that the electrical resistivity displays a sharp increase below 20 K, which value is about 105 higher than that of room temperature. And the Hall resistivity, which is linear, yielding an n-type carrier concentration as indicated (low T regime).
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GB/T 7714 | Zhang, Xin , Liang, Chaolong , Zhang, Jiuxing et al. Floating Zone Growth and Electricity Properties of Topological Kondo Insulator SmB6 [C] . 2014 . |
MLA | Zhang, Xin et al. "Floating Zone Growth and Electricity Properties of Topological Kondo Insulator SmB6" . (2014) . |
APA | Zhang, Xin , Liang, Chaolong , Zhang, Jiuxing , Liu, Wei . Floating Zone Growth and Electricity Properties of Topological Kondo Insulator SmB6 . (2014) . |
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Abstract :
Since the nanostructure was introduced to modify thermoelectric properties in 1993, many efforts have been devoted to fabricate nanostructures and investigate the electrical and thermal transports in nanostructured materials. Compared with low-dimensional materials, nanocomposites not only exhibit nanofeatures but also can be fabricated in large quantities and compatible with practical thermoelectric devices in scale and shape. This article reviews the background of nanocomposites, then the Mg-2(Si0.4Sn0.6)Bi-x solid solutions. High-manganese silicides with MnSi (HMS-MnSi), and In4-xGdxSe3 compounds are selected as examples to illustrate the combination effect of nanostructure and dopants on thermoelectric properties. In situ nanostructures successfully formed during the rapid cooling and spark-plasma sintering processing and elemental doping were achieved via melting processing. Electrical conductivities were enhanced as a result of the increased carrier concentration or carrier mobility by elemental doping. Meanwhile, thermal conductivities decreased as a result of the strong phonon scattering intensified by nanostructures. The ZTs for the specimens with optimal doping ratio were enhanced in these three types of thermoelectric materials.
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GB/T 7714 | Zhao, Ran , Guo, Fu , Shu, Yutian et al. Improvement of Thermoelectric Properties Via Combination of Nanostructurization and Elemental Doping [J]. | JOM , 2014 , 66 (11) : 2298-2308 . |
MLA | Zhao, Ran et al. "Improvement of Thermoelectric Properties Via Combination of Nanostructurization and Elemental Doping" . | JOM 66 . 11 (2014) : 2298-2308 . |
APA | Zhao, Ran , Guo, Fu , Shu, Yutian , Zhang, Xin , Lu, Qingmei , Zhang, Jiuxing . Improvement of Thermoelectric Properties Via Combination of Nanostructurization and Elemental Doping . | JOM , 2014 , 66 (11) , 2298-2308 . |
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Abstract :
The relationship between riding comfort and pavement roughness were studied from the view point of the road users in this research. RMSSD was selected to study passengers' riding comfort as a main evaluation index. In this study, 12 pavement sections with roughness changing from 1.06 to 5.53 m/km were selected to conduct on driving test in field. Test results show that, under different driving speed RMSSD changes obviously when the pavement roughness changes. In combination with the subjective scoring method and acceleration evaluation method, the critical value of roughness based on comfort considerations is proposed at different speeds.
Keyword :
Critical value; HRV (heart rate variability); IRI(international roughness index); Riding comfort Critical value; HRV (heart rate variability); IRI(international roughness index); Riding comfort
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GB/T 7714 | Zhang, J.-X. , Du, Y.-H. . Evaluation method of asphalt pavement roughness based on passengers' riding comfort [J]. | Journal of Beijing University of Technology , 2013 , 39 (2) : 257-262 . |
MLA | Zhang, J.-X. et al. "Evaluation method of asphalt pavement roughness based on passengers' riding comfort" . | Journal of Beijing University of Technology 39 . 2 (2013) : 257-262 . |
APA | Zhang, J.-X. , Du, Y.-H. . Evaluation method of asphalt pavement roughness based on passengers' riding comfort . | Journal of Beijing University of Technology , 2013 , 39 (2) , 257-262 . |
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Abstract :
By the experimental modal testing to the main structure of a high-speed horizontal machining center, the modal parameters such as the natural frequency, damping ratio, stiffness and mode shapes are obtained. By analyzing the dynamic characteristics, the weak links of this structure is at the spindle front bearing and the vertical column on which the screw driving the spindle box to move in vertical direction is mounted are determined, and provide an important basis of optimizing the structure for the machining center. And the amplitude-frequency characteristic curves of the weak structure evaluate the dynamic stiffness as the key indicators to provide reliable data for improving processing accuracy and cutting ability of machining center. The analysis results show that experimental modal analysis is a effective test method for improving the anti-vibration performance and machining stability of domestic machining centers.
Keyword :
Dynamic characteristic; Machining center; Modal test Dynamic characteristic; Machining center; Modal test
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GB/T 7714 | Wang, M. , Nan, J.-Y. , Zan, T. et al. Experimental modal analysis to the main structure of high-speed horizontal machining center [J]. | Journal of Beijing University of Technology , 2013 , 39 (5) : 648-652 . |
MLA | Wang, M. et al. "Experimental modal analysis to the main structure of high-speed horizontal machining center" . | Journal of Beijing University of Technology 39 . 5 (2013) : 648-652 . |
APA | Wang, M. , Nan, J.-Y. , Zan, T. , Zhang, J.-X. . Experimental modal analysis to the main structure of high-speed horizontal machining center . | Journal of Beijing University of Technology , 2013 , 39 (5) , 648-652 . |
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Abstract :
Polycrystalline rare-earth hexaboride (LaxCe1-x)B-6 were prepared by means of the reactive spark plasma sintering (SPS), using mixed powders of GdH2, NdH2 and B. The crystal structure, surface texture, mechanical property, electrical resistivity, and thermionic emission properties of the sintered samples were investigated. It is found that all the samples sintered by SPS exhibit high density (> 96%) and high value of Vickers hardness (2310 kg/mm(2)), which are much higher than those made by traditional method. Thermionic emission results indicate that the maximum emission current density of La0.6Ce0.4B6 is 40.7 A/cm(2) under the applied voltage of 1 kV at 1873 K, which is larger than that of LaB6 and CeB6. Thus, the mixed cystal of borides (LaxCe1-x)B-6, as a cathode, promises good prospects in application.
Keyword :
rare-earth hexaboride rare-earth hexaboride cathode materials cathode materials thermionic emission thermionic emission
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GB/T 7714 | Bao Li-Hong , Narengerile , Tegus, O. et al. Synthesis and properties of LaxCe1-xB6 compounds by in-situ spark plasma sintering [J]. | ACTA PHYSICA SINICA , 2013 , 62 (19) . |
MLA | Bao Li-Hong et al. "Synthesis and properties of LaxCe1-xB6 compounds by in-situ spark plasma sintering" . | ACTA PHYSICA SINICA 62 . 19 (2013) . |
APA | Bao Li-Hong , Narengerile , Tegus, O. , Zhang Xin , Zhang Jiu-Xing . Synthesis and properties of LaxCe1-xB6 compounds by in-situ spark plasma sintering . | ACTA PHYSICA SINICA , 2013 , 62 (19) . |
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Abstract :
The high quality LaxCe1 B-x(6) (x = 0, 0.2, 0.4, 0.6, 1) single crystals with large emission current density have been successfully grown by floating zone method. The crystal structure, crystal quality and emission properties of LaxCe1 B-x(6) single crystals were characterized by 360 degrees Phi scanning single crystal diffractometer, X-ray Laue diffraction and the thermal electron emission measurements. It is found that the as-grown crystals have a good crystal quality without subgrains and twin crystal phenomenon. The thermionic emission measurement results show that the maximum emission current density on (100) surface of La0.2Ce0.8B6 single crystal is 71.2 A/cm(2) at 1873 K under an applied voltage of 800 V, which is larger than the reported values in the literatures up to now. Furthermore, the crystals with different components also show a higher emission current density such as 53.8A/cm(2) for La0.4Ce0.6B6 and 53.3 A/cm(2) for CeB6 single crystals. The field emission single tip made by LaB6 single crystal shows a superior performance than the polycrystalline LaB6 field emission tip and its field enhancement factor (beta) is 36,231 cm (1). Thus, the LaxCe1 B-x(6) single crystals will have promising application prospects as a hot or cold cathode. (C) 2012 Elsevier B.V. All rights reserved.
Keyword :
Single crystal Single crystal Emission property Emission property Rare-earth hexaborides Rare-earth hexaborides Floating zone method Floating zone method
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GB/T 7714 | Bao, Li Hong , Tegus, O. , Zhang, Jiu Xing et al. Large emission current density of LaxCe1-xB6 high quality single crystals grown by floating zone technique [J]. | JOURNAL OF ALLOYS AND COMPOUNDS , 2013 , 558 : 39-43 . |
MLA | Bao, Li Hong et al. "Large emission current density of LaxCe1-xB6 high quality single crystals grown by floating zone technique" . | JOURNAL OF ALLOYS AND COMPOUNDS 558 (2013) : 39-43 . |
APA | Bao, Li Hong , Tegus, O. , Zhang, Jiu Xing , Zhang, Xin , Huang, Ying Kai . Large emission current density of LaxCe1-xB6 high quality single crystals grown by floating zone technique . | JOURNAL OF ALLOYS AND COMPOUNDS , 2013 , 558 , 39-43 . |
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Abstract :
The inherently high magnetic anisotropy and nanoscale grain size in a Sm5Co19 compound result in an intrinsic coercivity far higher than those of known Sm-Co compounds prior to orientation treatment. The combination of ultrahigh intrinsic coercivity, high Curie temperature and low coercivity temperature coefficient of nanocrystalline Sm5Co19 as a single phase material shows it to be a very promising compound to develop outstanding high-temperature permanent magnets.
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GB/T 7714 | Zhang, Zhexu , Song, Xiaoyan , Qiao, Yinkai et al. A nanocrystalline Sm-Co compound for high-temperature permanent magnets [J]. | NANOSCALE , 2013 , 5 (6) : 2279-2284 . |
MLA | Zhang, Zhexu et al. "A nanocrystalline Sm-Co compound for high-temperature permanent magnets" . | NANOSCALE 5 . 6 (2013) : 2279-2284 . |
APA | Zhang, Zhexu , Song, Xiaoyan , Qiao, Yinkai , Xu, Wenwu , Zhang, Jiuxing , Seyring, Martin et al. A nanocrystalline Sm-Co compound for high-temperature permanent magnets . | NANOSCALE , 2013 , 5 (6) , 2279-2284 . |
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Abstract :
A variety of intermetallic compounds in the binary Sm-Co system were reviewed, and the contents were focused on the crystal structures, magnetic properties and the nanoscale effects. The representative nanocrystalline Sm-Co compounds were introduced in details, the diagrams for their lattice structures and the atomic sites and occupancies were provided. Moreover, the magnetic properties of the nanocrystalline Sm-Co compounds were compared with those of the conventional polycrystalline counterparts. It showed that the nanocrystalline Sm- Co compounds exhibit special phase stability and remarkably enhanced magnetic performance, which are promising candidates for the matrix phases to develop permanent magnets, particularly the advanced high- temperature magnetic materials.
Keyword :
nanoscale nanoscale Sm-Co compounds Sm-Co compounds crystal structure crystal structure magnetic performance magnetic performance
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GB/T 7714 | Song, Xiao-Yan , Zhang, Zhe-Xu , Lu, Nian-Duan et al. Crystal structures and magnetic performance of nanocrystalline Sm-Co compounds [J]. | FRONTIERS OF MATERIALS SCIENCE , 2012 , 6 (3) : 207-215 . |
MLA | Song, Xiao-Yan et al. "Crystal structures and magnetic performance of nanocrystalline Sm-Co compounds" . | FRONTIERS OF MATERIALS SCIENCE 6 . 3 (2012) : 207-215 . |
APA | Song, Xiao-Yan , Zhang, Zhe-Xu , Lu, Nian-Duan , Liang, Hai-Ning , Li, Ding-Peng , Yan, Xiang-Quan et al. Crystal structures and magnetic performance of nanocrystalline Sm-Co compounds . | FRONTIERS OF MATERIALS SCIENCE , 2012 , 6 (3) , 207-215 . |
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Abstract :
Polycrystalline hexaborides (LaxGd1-x)B-6 (x = 0, 0.6, 0.8, 1) were synthesized by the reactive spark plasma sintering (SPS) method using a mixed powder of LaH2, GdH2 and B. The effects of La doping contents on the crystal structure, grain orientation, electrical resistivity and thermionic emission properties were investigated by x-ray diffraction, electron backscattered diffraction and emission current measurements, respectively. The results indicate that the high-purity (LaxGd1-x)B-6 cathode sintered by SPS exhibits high densification (> 97%) and a high value of the Vickers hardness (2375 kg mm(-2)). When the La doping contents are increased, the thermionic emission current density increases from 11.00 to 36.20 A cm(-2). Thus, the SPS technique is a suitable method for synthesizing dense rare-earth hexaborides with excellent properties.
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GB/T 7714 | Bao, Li-Hong , Zhang, Jiu-Xing , Zhang, Ning et al. In situ (LaxGd1-x)B-6 cathode materials prepared by the spark plasma sintering technique [J]. | PHYSICA SCRIPTA , 2012 , 85 (3) . |
MLA | Bao, Li-Hong et al. "In situ (LaxGd1-x)B-6 cathode materials prepared by the spark plasma sintering technique" . | PHYSICA SCRIPTA 85 . 3 (2012) . |
APA | Bao, Li-Hong , Zhang, Jiu-Xing , Zhang, Ning , Li, Xiao-Na , Zhou, Shen-Lin . In situ (LaxGd1-x)B-6 cathode materials prepared by the spark plasma sintering technique . | PHYSICA SCRIPTA , 2012 , 85 (3) . |
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Abstract :
Ternary DyFeB nanoparticles and nanoflakes were prepared by surfactant-aid high-energy ball milling. As the particle size decreases, the coercivity decreases from 16.8 to 0.4 kOe, indicating substantial influence of the size on the coercivity of the particles. In addition, strong magnetic anisotropy was achieved in magnetically aligned DyFeB nanoflakes.
Keyword :
DyFeB DyFeB nanoflakes nanoflakes magnetic anisotropy magnetic anisotropy nanoparticles nanoparticles Coercivity Coercivity
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GB/T 7714 | Yue, Ming , Liu, R. M. , Liu, W. Q. et al. Ternary DyFeB Nanoparticles and Nanoflakes With High Coercivity and Magnetic Anisotropy [J]. | IEEE TRANSACTIONS ON NANOTECHNOLOGY , 2012 , 11 (4) : 651-653 . |
MLA | Yue, Ming et al. "Ternary DyFeB Nanoparticles and Nanoflakes With High Coercivity and Magnetic Anisotropy" . | IEEE TRANSACTIONS ON NANOTECHNOLOGY 11 . 4 (2012) : 651-653 . |
APA | Yue, Ming , Liu, R. M. , Liu, W. Q. , Zhang, D. T. , Zhang, J. X. , Guo, Z. H. et al. Ternary DyFeB Nanoparticles and Nanoflakes With High Coercivity and Magnetic Anisotropy . | IEEE TRANSACTIONS ON NANOTECHNOLOGY , 2012 , 11 (4) , 651-653 . |
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