Papers by Author: Tao Li

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Authors: Xue Tao Yuan, Xu Dong Lv, Yu Gao Zhou, Zhi Qiang Hua, Yang Lei, Lei Wang, Tao Li
Abstract: Over potentials for oxygen evolution reaction, corrosion rate, surface product after polarization and microstructure before and after polarization of Pb-0.2%Ag-0.08%Ca-0.05%Sr quaternary anode in zinc electrowinning were studied and compared with Pb-0.6%Ag binary anode. The results show that over potentials for oxygen evolution reaction on Pb-0.6%Ag and Pb-0.2%Ag-0.08%Ca-0.05%Sr anodes are 675 mV and 790 mV, respectively, while the corrosion current density are 8.2μAcm-2 and 20.1μAcm-2. The surface structure after experiment of in Pb-Ag anodes is dense and tightly attached to the base, while the surface of Pb-Ag-Ca-Sr is loose and porous. The phases of the surface are PbO2, PbSO4 and MnO2 on both anods.
Authors: Yong Yang, Xiao Jing Zheng, Tao Li, Zhi Qiang Hua
Abstract: The levitation between high temperature superconductors (HTSs) and permanent magnets (PMs) has been applied to the flywheel energy storage systems and magnetic bearing systems for the last nearly twenty years. The interaction forces acting on the levitating body are calculated by the modified frozen-image method. The magnetic dipoles are equivalent to Amperian current loops. The current intensity in loops changes linearly when the PM moves. Under the zero field cooling condition, the expression of vertical force is obtained when the PM traverses vertically, and when the PM traverses horizontally, the expressions of vertical and horizontal forces are obtained. Those expressions of vertical and horizontal forces are gained by calculating the forces between current loops and using superposition theorem of vector. The calculations agree well with the previous experimental data, which means that the deductions of the expressions are reliable.
Authors: Xue Tao Yuan, Xu Dong Lv, Zhi Qiang Hua, Lei Wang, Tao Li
Abstract: Anodic polarization behavior of ternary alloy Pb-0.08%Ca-1%Sn is studied by potentiodynamic polarization measurements, corrosion rate, the products on electrode surface after polarization, and microstructure of anode mud after polarization in electrowinning cell. The results show that Pb-Ca-Sn anode is easy to be passivated in electrolyte for copper electrowinning, the maintaining passivity current density is 97.72 µA•cm-2 and the corrosion products on the surface of Pb-Ca-Sn electrode present loose scaly, being composed of α-PbO2, β- PbO2 and PbSO4 after polarization.
Authors: Yun Yi Wu, Lei Wang, Zhi Qiang Hua, Tao Li, Xue Tao Yuan, Xu Dong Lv
Abstract: Pure, La3+ doped at A site, V5+ doped at B site, and La3+ and V5+ co-doped ferroelectric Bi4Ti3O12 (BTO), Bi3.25La0.75Ti3O12 (BLT), Bi4Ti2.98V0.02O3 (BTV) and Bi3.25La0.75Ti2.98V0.02O12 (BLTV) were successfully prepared by conventional sintering technique. The structures of the ceramics were investigated by X-ray diffraction, Raman spectroscopy, and scanning electron microscopy. X-ray diffraction indicated that assemblages of all sintered ceramics consist of a single phase of Bi4Ti3O12, implying that the A-site La3+ and B-site V5+ substitutions in this case do not affect the layered structure. Among these ceramics, BLTV ceramic exhibited the best electrical properties. The leakage current density of BLTV ceramic was only 1.3×10-4 Acm-2 at 40 KVcm-1, two orders of magnitude lower than BTO ceramic. Besides, a saturated ferroelectric hysteresis loops with largest remnant polarization 2Pr of 30.6μC/cm2 was observed for this sample. These suggested that the co-doped Bi4Ti3O12 ceramic by La3+ and V5+ at A and B sites showed advantages in application over the pure BTO, doped BLT and BTV ceramic, respectively.
Authors: Yun Yi Wu, Xue Tao Yuan, Zhi Qiang Hua, Tao Li, Lei Wang
Abstract: The Bi3.25La0.75O12 films were prepared on the Pt/TiO2/SiO2/Si substrate using RF-magnetron sputtering method. The effects of sputtering conditions, including sputtering pressure, oxygen partial pressure and substrate temperature on microstructure, ferroelectric properties were investigated. When deposited at low substrate temperature (room temperature), the BLT thin film exhibits preferentially c-axis oriented. With the increasing of substrate temperature, the (117) diffraction peak become stronger, indicating the changing of the microstructure in the BLT films. The BLT film samples deposited at 4.5-6Pa exhibit desired bismuth-layered structure, with no any preferred orientation. However, when BLT films were deposited above 5 Pa, some weak pyrochlore diffraction peaks appear in the X-ray diffraction pattern. The Pr is a maximum for the BLT film deposited at 5 Pa with O2/Ar ratio 1/5 and decreases with both decreasing and increasing deposition pressure.
Authors: Xu Dong Lv, Xue Tao Yuan, Zhi Qiang Hua, Lei Wang, Tao Li, Yu Gao Zhou, Zhi Wei Wei
Abstract: Prepared lead dioxide(PbO2) coating on a Ti substrate by pulse current technique. The effect of the pulse current density, pulse time and relaxation time on the morphology and electrochemistry properties of the coating was studied by means of scanning electron microscopy and electrochemistry station. Compared with lead dioxide fabricate by common electroplate technique, lead dioxide coating prepared by pulse current technique is more dense, without hole, better corrosion resisting property and more stable electrochemistry properties.
Authors: Yun Yi Wu, Jian Gao, Tao Li, Zhi Qiang Hua
Abstract: PbO-type structure β-FeSe superconductor ceramic were successfully prepared by solid state sinter method in high vacuum state. The structures of the ceramics were investigated by X-ray diffraction and scanning electron microscopy. X-ray diffraction indicates that the sample prepared by two-steps method exhibited a much improved crystallinity. And as sintering temperature increases to 700°C, secondary phase Fe7Se8 phase peak disappear and α-Fe peak weakened. Besides, the ceramic prepared in 700°C exhibited a denser surface morphology in comparison to that prepared in 410°C and its composition is closer to the chemical formula FeSe according to EDX compositional analyses. It was noted that the resistivity of the sample, sintered at 700°C using two-steps sinter method, shows a linear metallic behavior from room temperature and onset is around T = 7.5 K.
Authors: Yun Yi Wu, Lei Wang, Zhi Qiang Hua, Tao Li
Abstract: A series of ferroelectric BIT ceramics with various V2O5 dopants were prepared by conventional solid-state route. The influence of V2O5 dopant on microstructural and electrical properties of BIT ceramic were investigated in detail, which were examined by XRD, Raman spectra and P-E hysteresis loops, etc. X-ray Photoelectron Spectroscopy was used to examine the chemical state of the vanadium ions inside the BIT ceramics. Vanadium added to the BIT system can enhance the ferroelectric property due to the decrease of the concentration of space charge occurred during calcinations and weaken the polarization property due to the decrease of grain size and the change of chemical valence for vanadium ion. The BIT ceramic with 3 mol% V2O5 dopant exhibits a remnant polarization 2Pr of 25.6 μC/cm2, and coercive field Ec of 47.4 KV/cm. Besides, the conductivity of BTV was obviously lower than that of the undoped BIT, which was accord with donor dopants decreasing the conductivity of a material with a p-type mechanism.
Authors: Qin Li Lv, Jian Wang Cai, Tao Li
Abstract: A novel perpendicular magnetic material was obtained in the annealed Co/native oxide/Pd multilayer films. Upon thermal annealing in a vacuum, a sharp transition of magnetic anisotropy from in-plane to out-of-plane is observed for the Co/native oxide/Pd multilayers with 20 Å Co layers. These annealed Co/native oxide/Pd multilayers possess extremely large effect perpendicular anisotropy field (Heff) and perpendicular anisotropy energy (Ku), with the maximum Heff of 17 kOe and Ku of 5.1×106 erg/cm3 obtained in the annealed Co(20 Å)/native oxide/Pd(10 Å) multilayers. Moreover, the large perpendicular magnetic anisotropy sustains with annealing temperature varying from 200°C to 400°C, indicative of high thermal stability. The present results open the way to a third alternative for the realization of thermally stable perpendicular magnetic electrodes of tunnel junctions.
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