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growth orientation and superconducting properties of YBa_2Cu_3O_(7-δ) films prepared by the low-fluorine sol-gel process

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Journal of Semiconductors 2010年第8期31卷 35-41页

作者：雷黎赵高扬徐慧赵娟娟 School of Materials Science and Engineering Xi'an University of Technology

YBa_2Cu_3O_（7-δ）（YBCO） films were deposited on（100）-oriented LaAlO_3（LAO） single crystal substrates by the dip-coating process using low-fluorine *** microstructures were characterized with the aid of X-ray diffractometry,scanning electron microscopy and high-resolution transmission electron *** superconducting properties were measured by the standard four-probe *** experiment results show that the film obtained under high enough humidity conditions exhibits better c-axis texture and superconducting properties than the film under a relatively low humidity *** on the classical nucleation and chemical reaction thermodynamics theory, the underlying crystalline and growth mechanisms of YBCO films under certain humidity conditions are explained in combination with our experimental *** is suggested that the unreacted intermediate phases such as BaF_2 and CuO aggregated in the YBCO grain boundary will cause lattice distortion in the YBCO matrix and further induce the formation of a-axis oriented YBCO grains as crystallization ***,it is believed that the relative content of water vapor within the heat-treatment atmosphere plays quite an important role in the preparation of c-axis oriented YBCO film with good superconducting properties.

关键词： YBCO films low-fluorine process growth orientation sol-gel

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Microstructure Evolution and growth orientation of Directionally Solidified Mg–4 wt% Zn Alloy with Different growth Rates

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Acta Metallurgica Sinica(English Letters) 2017年第12期30卷 1185-1191页

作者： Hong-Min Jia Xiao-Hui Feng Yuan-Sheng Yang Institute of Metal Research Chinese Academy of SciencesShenyang 110016 China University of Chinese Academy of Sciences Beijing 100039China Shandong Key Laboratory for High Strength Lightweight Metallic Materials Ji'nan 250014 China

The microstructure evolution and growth orientation of directionally solidified Mg-4 wt% Zn alloy in the growth rate range from 20 to 200μm/s were investigated. A typical cellular structure was observed with a growth rate of 20 μm/s, and the cellular spacing was 115 μm. When the growth rate increased to 60 μm/s, cellular structure with some developed perturbations was obtained and the cellular spacing was 145 μm, suggesting that the cell-to-dendrite transition happened at the growth rate lower than 60 μm/s. As the growth rate further increased, the microstructure was dendritic and the primary dendritic arm spacing decreased. The relationship between the primary dendritic arm spacings and the growth rates was in good agreement with Trivedi model during dendritic growth. Besides, X-ray diffraction and transmission electron microscopy analyses showed that the growth direction of directionally solidified Mg-4 wt% Zn alloy was （1120） lay in {0002} crystal plane, and the preferred orientation was explained with the lattice vibration model for one-dimensional monatomic chain.

关键词： Directional solidification Mg-Zn alloy Microstructure evolution Primary dendritic arm spacing growth orientation

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Modeling of equiaxed and columnar dendritic growth of magnesium alloy

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Transactions of Nonferrous Metals Society of China 2012年第9期22卷 2212-2219页

作者：吴孟武熊守美清华大学机械工程系北京100084 清华大学汽车安全与节能国家重点实验室北京100084

Based on the cellular automaton （CA） method, a numerical model was developed to simulate the dendritic growth of magnesium alloy with HCP crystal structure. The growth kinetics was calculated from the complete solution of the transport equations. By defining a special neighborhood configuration with the square CA cell, and using a set of capturing rules which were proposed by BELTRAN-SANCHEZ and STEFANESCU for the dendritic growth of cubic crystal metals during solidification, modeling of dendritic growth of magnesium alloy with different growth orientations was achieved. Simulation of equiaxed dendritic growth and columnar dendritic growth under directional solidification was carried out, and validation was performed by comparing the simulated results with the experimental results and those in the previously published works.

关键词： magnesium alloy dendritic growth cellular automaton method growth orientation

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Preparation and permeability of ZSM-35 zeolite membranes on porous stainless steel tubes

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Frontiers of Chemical Science and Engineering 2007年第3期1卷 217-220页

作者： ZHU Gang WANG Jinqu ZHANG Yan LU Jinming XIU Jinghai State Key Laboratory of Fine Chemicals Institute of Adsorption and Inorganic MembraneDalian University of TechnologyDalian 116012China Dalian University of Technology Greentech Co. LtdDalian 116012China

ZSM-35 zeolite membranes were prepared on porous stainless steel tubes with silica sol and tetraethoxysi-lane as silica source,and with 1-butylamine and ethylenedi-amine as templates,*** characterization of X-ray diffraction(XRD)and scanning electron microscopy(SEM)showed that the membranes prepared with ethylene-diamine as the template displayed growth orientation with their crystal planes(h00)parallel to the support *** single-component permeability tests of H2,N2 and C3H8 showed that the membranes synthesized with ethylene-diamine as the template,compared with those with 1-butylamine as the template,showed relatively higher permeation rates and ideal separation factors,and above their corresponding ideal Knudsen diffusion factors,which might be attributed to the different growth orientation of zeolite membranes synthesized with different templates.

关键词： ZSM-35 zeolite membrane porous stainless steel gas permeation growth orientation

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