Sol－Gel法制备YBa_2Cu_3O_（7－x）超细粉末研究

用柠檬酸盐作螯合剂，用氨水调节溶液的酸度，通过Ｓｏｌ－Ｇｅｌ转变制得了粒径为１００ｎｍ大小的ＹＢａ２Ｃｕ３Ｏ（７－ｘ）超细粉末，对ＹＢａ２Ｃｕ３Ｏ（７－ｘ）在合成反应中溶胶的形成和凝胶聚合过程进行了研究和探讨。Ｓｏｌ－Ｇｅｌ法制得的ＹＢａ２Ｃｕ３Ｏ（７－ｘ）超细粉末在粒度、纯度、烧结特性和超导性能上，均优于固态反应合成方法。     

YBa2Cu3O7超导相的水解反应

超导相ＹＢａ２Ｃｕ３Ｏ７与水发生强烈反应．反应产物为ＣｕＯ，Ｂａ（ＯＨ）２和Ｙ２ＢａＣｕＯ５，并放出氧气．这主要是因为超导相中存在Ｃｕ３＋离子．环境中水气氛的存在将大大影响ＹＢａ２Ｃｕ３Ｏ７超导性．     

BaZrO3颗粒分散混合导体YBa2Cu3O7-δ的微结构与性能研究

通过在YBa2Cu3O7-δ的起始原料中直接掺入过量的BaO和等摩尔ZrO2,原位生成均匀弥散分布的BaZrO3第二相颗粒的方法制备YBa2Cu3O7-δ-BaZrO3复合混合导体材料.研究了引入第二相BaZrO3颗粒对基相YBa2Cu3O7-δ的微观结构、热膨胀行为和力学性能的影响.发现弥散的BaZrO3颗粒能有效地抑制YBa2Cu3O7-δ沿C轴方向的生长,使晶粒由条形变为方形.与YBa2Cu3O7-δ单相样品相比,含10 mol%BaZrO3颗粒的样品具有更高的相对密度和较低的热膨胀系数以及显著改善的力学强度.     

Transition of Y<Subscript>2</Subscript>BaCuO<Subscript>5</Subscript> phase in powder melting processed YBa<Subscript>2</Subscript>Cu<Subscript>3</Subscript>O<Subscript>7−x</Subscript> superconductors

The morphology and the formation of Y2BaCuO5 phase in powder melting processed YBa2Cu3O7-x superconductors were investigated. The experimental results show the heat treatment can not change the shape of Y2BaCuO5 particles in powder melting processed samples. The formation of round Y2BaCuO5 phase is due to relative content of each constitution of precursor powders in powder melting process. For powder melting process, the excessive liquid phase is eliminated, which restrains the preferred growth of Y2BaCuO5 ...     

LOW TEMPERATURE MAGNETIC FORCE MICROSCOPY STUDY OF VORTEX IN A YBa_2Cu_3O_(7-x) THIN FILM

A low temperature magnetic forc micro-scope for the study of high temperature superconductor isdeveloped. It has been applied to spatially resolve singlevortices at low temperature (77K) in a YBa_2Cu_3,O_(7-x). thinfilm deposited by laser ablation on a NdGaO_3 substrate.The images of disordered vortex arrangements are obtained. The movement of single vortices after a contactmode scanning of the detecting tip over the thin film sur-face is observed. The reason for the movement is dis-cussed.     

YBa_2Cu_3O_（7－δ）超导陶瓷螺旋谐振器

用ＹＢａ２Ｃｕ３Ｏ（７－δ）超导陶瓷裸线绕制了一定弹性和强度的螺旋谐振器内导体，整个ＹＢａ２Ｃｕ３Ｏ（７－δ）螺旋是导通和超导的。对比测试了室温和液氮温区下超导螺旋和同样尺寸Ｃｕ螺旋谐振器的品质因数（Ｑ），液氮温区（７７Ｋ、ｌ００ＭＨｚ）下，前者的Ｑ值比后者高３倍，初步显示了ＹＢａ２Ｃｕ２Ｏ（７－δ）高温超导体在这一领域应用的优越性。     

金属有机沉积法制备SrTiO3薄膜

采用金属有机沉积（MOD）法制备了SrTiO3（STO）外延薄膜作为YBa2Cu3O7-δ涂层导体的缓冲层.以乙酸锶、钛酸丁酯为前驱物配制了Sr离子浓度为0.125 mol.L-1的SrTiO3前驱溶液.研究了950℃下不同烧结时间（90、120、150 min）对在双轴织构的Ni-W（200）金属基带上沉积STO外延薄膜晶体取向和微观形貌的影响.结果表明,在950℃氩氢混合气氛（Ar-4%H2）下适宜于STO薄膜外延生长的最佳烧结时间为120 min;STO缓冲层薄膜表面平整致密,无裂纹和孔洞,具有良好取向,可作为YBa2Cu3O7-δ涂层导体的缓冲层.     

YBaCuO超导靶材制备工艺的研究

根据超导体相ＹＢａＣｕ３Ｏ７－Ｙ的晶体结构与含氧量、温度的关系，正确制订了ＹＢａＣｕＯ超导靶材的烧结工艺－预烧温度、烧结温及冷却速度，从而为用直流磁控溅射法研制高Ｔｃ、大临界电流密度Ｊｃ的超导薄膜提供了前提。     

Fe-doped epitaxial YBCO films prepared by chemical solution deposition

Railway Engineering Science - YBa2Cu3O7-δ (YBCO)-coated conductors have wide-ranging potential in large-scale applications such as superconducting maglev trains and superconducting electric...     

工艺参数对形成（Pb,La）TiO3溶胶和凝胶的影响

系统地研究了溶胶－凝胶技术制备Ｐｂ（１－ｘ）ＬａｘＴｉ（１－ｘ／４）Ｏ３的铁电陶瓷膜时催化剂、溶液浓度在室温下对形成溶胶和凝胶的影响规律；用约外光谱研究了成胶机理；用该技术成功地在（１００）Ｓｉ单晶衬底上制备出了均匀、无裂纹且具有钙铁矿结构的ＰＬＴ晶态薄膜。     

Simulation and experiment of vortex transport properties in a Type Ⅱ superconductor with grain boundary

We firstly described a simulation model to investigate the influence of grain boundary(GB)on the vortex transport properties in YBCO film.It is found that the size of inhomogeneous area caused by GB as well as the average velocity in transverse and longitudinal directions shows an angular dependence when the angle between the GB and the sample edge varies.We have also studied the impact of magnetic field intensity on dynamic behavior of vortex lattice and found that a lower vortex density makes it difficult for the vortex lattice to transfer from pinning state to flow state.As the magnetic field is decreased beyond a critical value,sharp jumps and strong fluctuations were observed in the I-V curve.Finally,we conducted measurements on a thin film YBa2Cu3O7 with an individual artificial grain boundary to support the simulation process.     

ZrO2/Al2O3复合载体中ZrO2的晶相和晶粒尺寸对Ni基催化剂性能的影响

用沉积-沉淀和溶胶-凝胶等法在扩孔后的Al2O3基载体上分别制备了不同ZrO2晶相和品粒尺寸的负载型纳米ZrO2／Al2O3复合载体，并用浸渍法制备了Ni／ZrO2／Al2O3．考察了纳米ZrO2品型结构和品粒尺寸对CO2重整CH4催化剂Ni／ZrO2／Al2O3的性能影响．结果表明，四方相ZrO2（t—ZrO2）有利于提高催化剂的表面吸附性能和催化剂的稳定性，同时t-ZrO2晶粒尺寸越小，活性物种的分散度越高，催化剂的活性好．     

HIGH-Tc SUPERCONDUCTIVITY AND PERCOLATION

On microscopic and microstructural lev-els,the relations between high Tc superconduc-tivity and percolation have been discussed.On themicroscopic level,the critical oxygen concentra-tion in YBa_2Cu_30_7 with Tc around 90 K hasbeen obtained in terms of percolation.On themicrostruclural level,the percolation considera-tions have provided,usefully theoretical basisfor materials design of metal/high-Tc super-conducting phase(nonmetal)composites.     

Ca替代Y对YBa_2Cu_3O_(7-δ)超导电性的影响

用固相反应方法制备了Y_(1-x)Ca_xBa_2Cu_3O_y(x=0.0,0.02,0.05,0.10,0.15,0.20,0.50)系列样品,发现超导转变温度随x增加而呈线性下降。粉末x-射线衍射结果表明,在x≤0.15范围内,体系呈现出很好的正交单相性,晶格参数无明显变化。用碘滴定方法测量了体系的氧含量,发现随着x的增加,Cu的平均价态降低,氧含量减少。把上述结果同Y_(1-x)Pr_xBa_2Cu_3O_y作比较,表明氧含量和Cu的平均价态均不是决定Tc的直接因素。讨论了氧含量改变的可能位置和引起超导电性发生变化的原因。     

Synthesis of spin-ladder Sr<Subscript>14</Subscript>Cu<Subscript>24</Subscript>O<Subscript>41</Subscript> material by citrates sol-gel method

A new process to synthesize polycrystalline samples of Sr14Cu24O41 was presented. Firstly, dry gel powder of Sr14Cu24O41 was synthesized by the citrates sol-gel method, using Sr（NO3）2, Cu（NO3）2, ethylene glycol and citrate acid as raw materials. Then, polycrystalline samples of Sr14Cu24O41 were prepared by solid-state reaction. Thermal Gravimetric and Differential Thermal Analysis（TG-DTA） showed that the temperature for solid-state reaction is at 942 ℃. The samples are identified to be single phase by X-ray Diffraction（XRD） and Scanning Electron Microscopy（SEM）. The SEM pictures showed that the first-step particles were at even size of about 100 nm by this technique. The electronic transport measurements showed that the doping compound were semiconductor with a crossover temperature T in the Arrhenius plot of the resistivity versus temprature.     

液相合成不同形貌的Cu_2O微晶

以乙酸铜为铜源,L-抗坏血酸为还原剂,采用简单的液相反应制备不同形貌的Cu2O微晶,并进行了表征。考察了温度、反应物浓度、表面活性剂种类等条件对Cu2O微晶粒径及形貌的影响,初步探讨了Cu2O微晶的生长机理。实验结果表明:通过改变表面活性剂的种类,可以选择性地制备出不同形貌的Cu2O微晶。以PVP为表面活性剂时制备的是直径约为1μm的Cu2O微球,以PEG为表面活性剂时制备的是边长约为700 nm的Cu2O立方体。     

高温预先热处理提高YBa_2Cu_3O_(7-x)的临界电流密度

本文论述了高温预先热处理对YBa_2Cu_3O_(7-x)的组织和J_c的影响,通过此工艺可明显减少YBa_2Cu_3O_(7-x)的空洞和消除BaCO_3,经过高温预先热处理后的YBa_2Cu_3O_(7-x),它的J_c达到1140A/cm~2。     

钛酸锶钡(BST)薄膜SOL-GEL制备方法研究

利用碳酸盐代替部分醇盐，探讨了采用Sol-Gel技术制备Ba1-xSrxTiO3(BST)铁电薄膜的可行性。以醋酸钡[Ba(CH3COO)2]、碳酸锶[SrCO3]和钛酸四丁酯[Ti(OC4H9)4]作原料，运用一般的Sol-Gel工艺制备BST铁电薄膜，通过XRD分析物质结构，用SEM测定表面形貌，XPS及EDAX测定薄膜的组成。结果表明：采用碳酸锶原料和其他醇盐一起来制备BST铁电薄膜的方法是可行的。     

纳米钙钛矿负载型催化剂La_(0.8)Sr_(0.2)Co_(0.8)Mn_(0.2)O_3/γ-Al_2O_3的制备与评价

研制了一种替代净化机动车尾气所用贵金属催化剂的纳米钙钛矿型催化剂 .采用溶胶 -凝胶法制备了B位掺杂的纳米钙钛矿型复合氧化物La0 .8Sr0 .2 Co0 .8Mn0 .2 O3,并将其负载于自制的γ -Al2 O3上 ,于微反在线色谱装置上考察了负载后催化剂对丙烯腈合成反应释放气中的丙烷、CO和丙烯的氧化程度及工艺条件 .确定的最佳工艺条件为 :反应温度为 3 5 5℃ ,氧气体积分数为 89%～ 91% ,空速为 1.3× 10 3h- 1 ;在较宽松的反应条件下 ,丙烷、CO及丙烯的转化率均可达90 %以上 .结果表明 ,催化剂La0 .8Sr0 .2 Co0 .8Mn0 .2 O3/γ -Al2 O3被用于完全氧化反应具有很好的催化氧化活性 .     

温度及Y_2O_3对SG法制备ZrO_2相结构及粒度的影响

针对纳米ZrO2粉体粒径较小、比表面积大、极易发生团聚问题,以纳米ZrO2为研究对象,采用溶胶-凝胶(SG)法,以氧氯化锆为锆源,水为溶剂,Y2O3为稳定剂,PEG-6000为分散剂,主要研究烧结温度及Y2O3对制成的纳米ZrO2相结构及其粒度的影响.实验结果表明:经XRD分析,所制得的ZrO2试样主要为四方相结构,随着煅烧温度的升高,粉体粒径增大;SEM测试结果表明,在一定ZrO2陶瓷粉体粒度范围内,随着稳定剂Y2O3加入量的增加,粉体颗粒间的分散性有所改善.综合考虑对纳米ZrO2相结构及粒度的影响,确定最佳烧结温度为650℃,稳定剂Y的最佳加入量为7.5mol%,制备的ZrO2纳米粉体粒径尺度最佳,晶型稳定性好且分散性得到改善.