Improved barium fluoride process YBa2Cu3)7-x films via post-anneal monitoring

The continuous monitoring of the conversion, of Y, Cu and BaF₂ precursors to form superconductor thin films has been achieved using a fluorine-specific-ion electrode immersed in an effluent gas-washing cell. High-quality thin films of YBa₂Cu₃O_7-x deposited on NdGaO₃, LaA10₃ and LaGaO₃, have been produced by limiting the wet oxygen annealing phase of the post-deposition anneal. When the films were over-annealed in humidified oxygen the superconducting transition temperature as measured by inductive methods and the crystal quality, determined by x-ray rocking curves were degraded.     

TEM Analysis on YBCO Composited Superconducting Tapes

The microstructures of the YBCO composited superconducting tapes with different J_c were analysed byTEM.The relationship between microstructure and J_c of the tapes is discussed in detail.It is demonstrated thatJ_c value of the tapes increases significantly with the decrease in the width of grain boundary,increase of the twindensity and the reducing of the amount of precipitates at grain boundary.At grain boundary of the tapes,howev-er,small amount of non-superconducting phases can-not be avoided.For the fabrication of high J_c YBCO com-posited tapes,it is very important to improve the microstructure of the superconductor perfectly.     

YBCO／STO超导外延膜的X－射线双晶衍射研究

应用Ｘ－射线双晶衍射对磁控溅射法制备的ＹＢａ_２Ｃｕ_３Ｏ_（７－ｘ）／ＳｒＴｉＯ_３超导外延膜和衬底之间的位向关系以及晶体完整性的研究，表明衬底和外延在相应的衍射面之间存在与两者点阵常数差无关的位向差。这种位向差与测量方向（φ角）有关，在孪晶界方向出现极值。外延摇摆曲线的半峰宽值显示外延完整性较差，其值与测量方向有关，而不同方向上的点阵常数变化却不大。这可能分别与孪晶存在和孪晶有择优取向以及外延镶嵌块间夹角变化有关。     

铁掺杂Y－124高温超导相的电场梯度研究

将点电荷模型和有效价键理论结合起来，发展成点电荷－有效键价模型理论。并利用这种理论模型研究了在高Ｔｃ氧化物超导体Ｙ—１２４结构中被铁杂质原子所占据的有不同局域环境的铜晶位上的电场梯度和所对应的四极劈裂．利用这种方法建立了Ｆｅ（３＋）离子在亚晶格尺度上的位移与其电场梯度和周围各离子有效化合价的关系．根据实验中的四极劈裂观察值，从理论计算结果中得到对应于Ｆｅ－Ｏ五配位的Ｆｅ（Ｂ’）离子将偏离ＣｕＯ２面０．０１９５ｎｍ，而具有Ｆｅ－Ｏ六配位的Ｆｅ（Ｂ）离子将偏离０．０３９５ｎｍ．此两晶位上的电场梯度分别沿着＋Ｚ和－Ｚ方向。这种点电荷－有效键价模型对高Ｔｃ氧化物超导体实验中晶位的指认和Ｆｅ（３＋）的位移分析有重要的意义。     

Recrystallization Texture and Microstructure of Metal Substrate for Y123 Coated Superconductor

Thesecondgenerationofhigh temperaturesuper conductingtapesusingYBCO 12 3superconductorhavebeenanattractivesubjectinrecentyears .IncomparisonwithBibasedsuperconductors ,YBCOshowsbetterirreversibility ,lowAClosscapabilityandhighcriticalcurrentdensityJC inhighmagneticfields[1] .However ,owingtoitspropertyofphysicalmetallurgy ,YBCOtapescannotbeproducedbyOPIT(OxidePowderinTube)technique ,whichhasbeenusedinBibasedsuperconductorsuccessfully[2 ] .Fur thermore ,poorintergrainbondinginpolycrys…     

Developments of engineering applications of superconductivity at IRD

Progress in the three main areas of research at IRD is described. The developments noted cover superconducting dc motors, ac generators and fault current limiters.     

Bi2Sr2CaCu2O8＋x单晶的热导率测量

介绍了有关高温超导材料的热导率性质、测试方法和测试结果。结合我们的测试经验，讨论了稳态热流法测量高温超导体热导率应注意的问题。给出了Ｂｉ２Ｓｒ２ＣａＣｕ２Ｏ８＋ｘ单晶沿ａｂ面热导率的测试结果。     

The development of bi-based high-temperature superconductor and coil

Ag-sheathed Bi-2223 superconducting oxide conductors with a critical current density of 66,000 A/cm² at 77 K and coils that have generated magnetic fields of approximately 1.5 Tesla at 4.2 K have been successfully developed. The conductors consist of piled-up bundles of four to six sheets of element tapes with transport currents of approximately 200 Amps. The core size limit (CSL) prevented the production of single conductors that had the capacity to transport a current as high as 200 Amps at 4.2 K. Until now, it was difficult to develop a conductor having both high critical current density and the capability of transporting a large amount of current simultaneously. The role of CSL in large scale applications of high temperature superconducting oxides is discussed.     

Superconducting shields for alternating magnetic fields

This paper describes a shield to guard a dc superconducting field from an ac field.