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Full-Text Articles in Engineering
Angular Dependence Of Pinning Potential, Upper Critical Field, And Irreversibility Field In Underdoped Bafe1.9co0.1as2 Single Crystal, Mahboobeh Shahbazi, Xiaolin Wang, S R. Ghorbani, S. X. Dou, K Y. Choi
Angular Dependence Of Pinning Potential, Upper Critical Field, And Irreversibility Field In Underdoped Bafe1.9co0.1as2 Single Crystal, Mahboobeh Shahbazi, Xiaolin Wang, S R. Ghorbani, S. X. Dou, K Y. Choi
Faculty of Engineering - Papers (Archive)
Underdoped BaFe1.9Co0.1As2 single crystal was studied by angular dependence of magneto-transport at fields up to 13 T over a wide range of temperature. Our results show that pinning potential, Uo, decreases slightly for h45 and remains constant for h45, while the upper critical field, Hc2, and the irreversibility field, Hirr, increase with h. According to anisotropic Ginzburg-Landau theory, the anisotropy was determined by scaling the resistivity under different magnetic fields below the superconducting critical temperature, Tc. Anisotropy, C, in the underdoped crystal is found to be temperature dependent and decreases from 2.1 to 1.8 for as T is reduced from …
Crystal Structure, Electronic Structure And Thermoelectric Properties Of N-Type Bisbste2, Sima Aminorroaya-Yamini, Chao Zhang, Xiaolin Wang, Ivan Nevirkovets
Crystal Structure, Electronic Structure And Thermoelectric Properties Of N-Type Bisbste2, Sima Aminorroaya-Yamini, Chao Zhang, Xiaolin Wang, Ivan Nevirkovets
Faculty of Engineering - Papers (Archive)
N-type bismuth telluride sulfide has received attention as a potential thermoelectric material due to its large thermopower and ability to form solid solutions with bismuth antimony sulfide. Here, we fabricated an n-type tetradymite BiSbSTe2 by solid-state reaction. The crystal structure was found to be rhombohedral, and the thermoelectric properties were measured for the temperature range 50–390 K. A high Seebeck coefficient of −190 μVK−1 was achieved at 385 K. The electronic structure of BiSbSTe2 was investigated using first-principles calculations and compared with its parent counterpart (Bi2STe2). The results have shown that BiSbSTe2 is a narrow band-gap semiconductor. For the first …
Competition Between The Crystal Field And The Exchange Field In Er3+ Doped Ndmno3, Fang Hong, Zhenxiang Cheng, Xiaolin Wang, S X. Dou
Competition Between The Crystal Field And The Exchange Field In Er3+ Doped Ndmno3, Fang Hong, Zhenxiang Cheng, Xiaolin Wang, S X. Dou
Faculty of Engineering - Papers (Archive)
A careful investigation of specific heat shows that the ground state splitting of Nd3þ has been modified by the Er3þ doping, as it shows a nonlinear dependence on the Er3þ doping rate, due to the competition between the crystal field and the exchange field. This competition could be further confirmed by the anomalies in the magnetic entropy and the ground state splitting found in Nd0.9Er0.1MnO3. On the contrary, the ground state splitting of Er3þ has a linear dependence on the doping rate, indicating its stronger dependence on the crystal field rather than the exchange field.
Dynamics Of Flux-Line Bundles And Voltage-Current Characteristics In A Ba(K)Fe2as2 Single Crystal, K H. Muller, S K. H Lam, Xiaolin Wang, S X. Dou
Dynamics Of Flux-Line Bundles And Voltage-Current Characteristics In A Ba(K)Fe2as2 Single Crystal, K H. Muller, S K. H Lam, Xiaolin Wang, S X. Dou
Faculty of Engineering - Papers (Archive)
Understanding the flux-line dynamics in layered superconductors is of utmost importance for many superconductor applications, yet extracting from measurements the relevant parameters remains a major challenge. Here we report on measurements and theoretical model calculations of voltage-current (V-I) characteristics of a superconducting Ba0.72K0.28Fe2As2 single crystal slightly below its transition temperature in perpendicular magnetic fields between 0.01 and 7 T. We propose a model that describes the flux-line dynamics above, as well as below, the depinning current. The model fits the experimental V-I characteristics remarkably well and is used to extract from the data the field dependence of (a) the depinning …
Infrared Phonon Anomaly And Magnetic Excitations In Single-Crystal Cu3bi(Seo3)2o2cl, K H. Miller, P W. Stephens, C Martin, E Constable, R A. Lewis, H Berger, G L. Carr, D B. Tanner
Infrared Phonon Anomaly And Magnetic Excitations In Single-Crystal Cu3bi(Seo3)2o2cl, K H. Miller, P W. Stephens, C Martin, E Constable, R A. Lewis, H Berger, G L. Carr, D B. Tanner
Faculty of Engineering - Papers (Archive)
nfrared reflection and transmission as a function of temperature have been measured on single crystals of Cu3Bi(SeO3)2O2Cl. The complex dielectric function and optical properties along all three principal axes of the orthorhombic cell were obtained via Kramers-Kronig analysis and by fits to a Drude-Lorentz model. Below 115 K, 16 additional modes [8(E∥â)+6(E∥b̂)+2(E∥ĉ)] appear in the phonon spectra; however, powder x-ray diffraction measurements do not detect a new structure at 85 K. Potential explanations for the new phonon modes are discussed. Transmission in the far infrared as a function of temperature has revealed …
Magnetic Properties In Polycrystalline And Single Crystal Ca-Doped Lacoo3, R Zeng, J C. Debnath, Dapeng Chen, P Shamba, Jianli Wang, S J. Kennedy, S J. Campbell, Tania M. Silver, S. X. Dou
Magnetic Properties In Polycrystalline And Single Crystal Ca-Doped Lacoo3, R Zeng, J C. Debnath, Dapeng Chen, P Shamba, Jianli Wang, S J. Kennedy, S J. Campbell, Tania M. Silver, S. X. Dou
Faculty of Engineering - Papers (Archive)
Polycrystalline (PC) and single crystalline (SC) Ca-doped LaCoO3 (LCCO) samples with the perovskite structure were synthesized by conventional solid-state reaction and the floating-zone growth method. We present the results of a comprehensive investigation of the magnetic properties of the LCCO system. Systematic measurements have been conducted on dc magnetization, ac susceptibility, exchange-bias, and the magnetocaloric effect. These findings suggest that complex structural phases, ferromagnetic (FM), and spin-glass/cluster-spin-glass (CSG), and their transitions exist in PC samples, while there is a much simpler magnetic phase in SC samples. It was also of interest to discover that the CSG induced a magnetic …
Visualization Of Vortex Motion In Feas-Based Bafe1.9ni0.1as2 Single Crystal By Means Of Magneto-Optical Imaging, Zhi W. Lin, Yong Jian Li, Jian G. Zhu, Xiaolin Wang, S. X. Dou, Youguang Guo, Gang Lei, Yi Wang, Matthew Philips, Michael Cortie, Yan-Cheng Li, Ki-Young Choi, Xun Shi
Visualization Of Vortex Motion In Feas-Based Bafe1.9ni0.1as2 Single Crystal By Means Of Magneto-Optical Imaging, Zhi W. Lin, Yong Jian Li, Jian G. Zhu, Xiaolin Wang, S. X. Dou, Youguang Guo, Gang Lei, Yi Wang, Matthew Philips, Michael Cortie, Yan-Cheng Li, Ki-Young Choi, Xun Shi
Faculty of Engineering - Papers (Archive)
Superconductivity has been found in newly discovered iron-based compounds. This paper studies the motion of magnetic vortices in BaFe1.9Ni0.1As2 single crystal by means of the magneto-optical imaging technique. A series of magneto-optical images reflecting magnetic flux distribution at the crystal surface were taken when the crystal was zero-field cooled to 10 K. The behavior of the vortices, including penetration into and expulsion from the single crystal with increasing and decreasing external fields, respectively, is discussed. The motion behavior is similar to that observed in high-Tc superconducting cuprates with strong vortex pinning; however, the …
Crystal Plasticity Finite Element Modelling Of Surface Roughness And Texture Of Metals, H Li, Z Jiang, D Wei, J Han
Crystal Plasticity Finite Element Modelling Of Surface Roughness And Texture Of Metals, H Li, Z Jiang, D Wei, J Han
Faculty of Engineering - Papers (Archive)
A crystal plasticity finite element method (CPFEM) model was developed to analyse the surface roughness transfer and texture of metals during metal forming. In order to investigate the crystal slip mechanism and influence of different polycrystalline models (Taylor-type model and finite element polycrystalline model) on finite element modelling, the uniaxial compression of FCC pure aluminum was carried out in laboratory, and the Taylor-type and finite element polyaystalline models are separately employed in the finite element software ABAQUS to simulate the development of the deformation texture by rate dependent crystal constitutive equations during three different deformation modes (free compression, uniaxial planar …
Viscoelastic Study Of Conducting Polymers Using Quartz Crystal Microbalance, Mehrdad Bahrami Samani, Philip G. Whitten, Geoffrey M. Spinks, Christopher David Cook
Viscoelastic Study Of Conducting Polymers Using Quartz Crystal Microbalance, Mehrdad Bahrami Samani, Philip G. Whitten, Geoffrey M. Spinks, Christopher David Cook
Faculty of Engineering - Papers (Archive)
Application of conducting polymers has been growing widely in different fields such as batteries, solar cells, capacitors and actuators. Mechanical properties of conducting polymers like flexibility, high power to mass ratio and high active strain make them potentially applicable to robotic and automation industries. Obviously, a dynamic model of the actuation phenomenon in conducting polymers is needed to study its controllability and also to optimize the mechanical performance. De Rossi and colleagues suggest treating the mechanical behaviour of conducting polymers separately from the viscoelastic structural model and electrochemical actuation[1]. But it has been observed that the effects of electrochemical actuation …
Thermomechanical Behavior Of Nickel Base Single Crystal Superalloy Towards Understanding Of Weld Hot Cracking, S S. Babu, J M. Vitek, S A. David, M Murugananth
Thermomechanical Behavior Of Nickel Base Single Crystal Superalloy Towards Understanding Of Weld Hot Cracking, S S. Babu, J M. Vitek, S A. David, M Murugananth
Faculty of Engineering - Papers (Archive)
"Thermomechanical responses of three single crystal superalloys were measured in between 600 and 1200 degrees C using a thermomechanical simulator. On-heating results showed no softening while testing below 1000 degrees C. In contrast, extensive softening was observed while testing above 1000 degrees C. This rapid softening is related to dissolution of gamma' precipitates. During on-cooling tests from 1300 degrees C, strength recovery of these samples occurred only below 900 degrees C. The delay in strength recovery is attributed to the extent of undercooling required for rapid decomposition of the gamma phase into mixture of gamma and gamma' phases."
Predication Of Multi-Dimensional Photonic Crystal Structures Generated By Multi-Beam Interference In Holographic Lithography, Jose F. Chicharo, Jiangtao Xi, Enbang Li
Predication Of Multi-Dimensional Photonic Crystal Structures Generated By Multi-Beam Interference In Holographic Lithography, Jose F. Chicharo, Jiangtao Xi, Enbang Li
Faculty of Engineering - Papers (Archive)
Photonic crystals (PCs) are synthetic micro-structures which have periodical refraction index variations and produce photonic band gaps similar to electronic band gaps produced by the crystal potentials of semiconductors. Different methods have been proposed and demonstrated to fabricate two- or three-dimensional photonic crystal structures. Among them, the holographic lithography method, in which multi-beam interference is employed, offers a number of advantages, including its ability to create large volume of periodic structures through an irradiation process, the uniformity of period, and more degrees of freedom to control the structures. In this study, a multi-beam interference model is presented for predicting the …