溶胶－凝胶法合成YBa_2Cu_3O_（7－δ）／Ag_x的复合超导体研究

采用溶胶－凝胶法制得了ＹＢａ２ＣｕａＯ７－δ超细粉和Ａｇ２Ｏ细粉，用特定的烧结方法制各得了ＹＢａ２Ｃｕ３Ｏ７－δ／Ａｇｘ（ｘ＝０～９０％Ｖｏｌ）系列超导块体。研究了含Ａｇ量不同时的ＹＢａ２Ｃｕ３Ｏ７－δ相材料的烧结特性和渗流行为特征，以及对ＹＢ２Ｃｕ３Ｏ７－δ／Ａｇｘ体系的密度、Ｔｃ、Ｊｃ产生的影响．     

YBa2Cu3O7—δ超导陶瓷螺旋谐振器

用ＹＢａ２Ｃｕ４Ｏ７－δ超导陶瓷裸线制了一定弹性和强度的螺旋谐唇振器内导体，整个ＹＢａ２Ｃｕ３Ｏ７－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，液氮湿区下，前的Ｑ值比后高３倍，初步显示了ＹＢａ２Ｃｕ２Ｏ７－δ高温超导体在这一领域应用的优越性。     

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。     

溶胶—凝胶法合成YBa2Cu3O7—δ／Agx的复合超导体研究

采用溶胶－凝胶法制得了ＹＢａ２Ｃｕ３Ｏ７－δ超细粉和Ａｇ２Ｏ细粉，用特定的烧结方法制备得了ＹＢａ２Ｃｕ３Ｏ７－δ／Ａｇｘ（ｘ＝０￣９０％Ｖｏｌ）系列超导块体。研究了含Ａｇ量不同时的ＹＢａ２Ｃｕ３Ｏ７－δ相材料的烧结特性和渗流行为特征，以及对ＹＢａ２Ｃｕ３Ｏ７－δ／Ａｇｘ体系的密试、Ｔｃ、Ｊｃ产生的影响。     

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。     

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。     

热处理对YBa_2Cu_3O_（7－x）的J_c影响

论述了热处理温度、时间、气氛对ＹＢａ＿２Ｃｕ＿３Ｏ＿（７－ｘ）的组织和Ｊ＿ｃ的影响，在氧气氛下热处理ＹＢａ＿２Ｃｕ＿３Ｏ＿（７－ｘ）的效果比在空气下效果好．最佳热处理条件为：８７０℃，３小时，２个大气压纯氧条件下，Ｊ＿ｃ值可达１１４０Ａ／ｃｍ￣２。     

高取向膜的1／f噪声

测量了几种高取向ＹＢＣｕｏ膜的１／ｆ噪声．结果显示，ＹＢａ２Ｃｕ３Ｏ７－　材料的噪声可能来源于样品中的晶粒边界．改善膜的微粒结构是减少１／ｆ噪声的一条有效途径．     

电子—声子作用对氧化物超导电性的影响

考虑电子一声子作用对氧化物超导电性的影响，推导出级数型临界温度公式，计算出ＹＢａ２Ｃｕ３Ｏ６．８的超导临界温度，计算值和实验值较吻合。     

YBa_2Cu_3O_(7-δ)超导体比热的测量

用绝热法测量了ＹＢａ＿２Ｃｕ＿３Ｏ＿（７－δ）高温超导体的比热，介绍了测量方法和测量装置，并给出了在液氦７７～１１０Ｋ温度区所测比热的结果．     

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.     

STUDY ON PREPARATION OF YBa_2Cu_3O_(7-x) ULTRAFINE POWDERS BY SOL-GEL PROCESS

The ultrafine powders of YBa_2Cu_3O_(7-x) withthe size of 100nm were synthesized by Sol-Gel process using cit-rate as complex and ammonium hydroxide to adjust pH of solu-tion. The process of Sol formation and Gel polymerization ofYBa_2Cu_3O_(7-x) in the Sol-Gel synthetic reaction has bee studied.The particle size,pruity,sintering activity and superconductingproperties of YBa_2Cu_3O_(7-x)prepared by Sol-Gel method are betterthan by solid state reaction.     

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 ...     

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.     

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.     

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...     

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.