Effect of Ingredients on Magnetic Lifting Property in Bulk Melt－Textured YBCO

ＥｆｆｅｃｔｏｆＩｎｇｒｅｄｉｅｎｔｓｏｎＭａｇｎｅｔｉｃＬｉｆｔｉｎｇＰｒｏｐｅｒｔｙｉｎＢｕｌｋＭｅｌｔ－ＴｅｘｔｕｒｅｄＹＢＣＯＦｕＸｕｅｋｕｉ；ＸｉａｏＬｉｎｇ；ＲｅｎＨｏｎｇｔａｏ（ＧｅｎｅｒａｌＲｅｓｅａｒｃｈＩｎｓｔｉｔｕｔｅｆｏｒＮｏ...     

Microstructure of YBCO Superconducting Film on Metal Substrate with YSZ Buffer Layer

ＭｉｃｒｏｓｔｒｕｃｔｕｒｅｏｆＹＢＣＯＳｕｐｅｒｃｏｎｄｕｃｔｉｎｇＦｉｌｍｏｎＭｅｔａｌＳｕｂｓｔｒａｔｅｗｉｔｈＹＳＺＢｕｆｅｒＬａｙｅｒＷａｎｇＪｉｎｇ（王敬），ＬｉｕＡｎｓｈｅｎｇ（刘安生），ＳｈｉＤｏｎｇｑｉ（石东奇），ＷａｎｇＸｉａｏ...     

Effect of substrate surface modification using Ag nano-dots on the improvement of J c and microstructures in YBa2Cu3O7 thin films grown on LaAlO3 (100) by pulsed laser deposition

YBa₂Cu₃O₇ (Y123) thin films were grown by pulsed laser deposition (PLD) on LaAlO₃ (100) substrates whose surfaces were modified by a discontinuously layer of Ag nano-dots. The Y123 films were characterised by atomic force microscope, X-ray diffraction, scanning electron microscope, and DC magnetization measurements. Effect of substrate surface modification using various densities of the Ag nano-dots on the improvements of critical current density J _c and microstructures in the Y123 films has been studied systematically. The results showed that at fixed physical deposition conditions J _c increased with the number of Ag shots, n. Zero field J _c at 77 K increased from 10⁶ to 3.3 × 10⁶ A/cm², and from 1.5 × 10⁷up to 4 × 10⁷A/cm² for 5 K as the number of Ag shots increased from zero to 150. However, a fluctuation of J _c was observed for n < 60 at 77 and 40 K in both low and high fields. Detailed microstructure analysis revealed that ab misalignment was gradually improved as Ag nano-dots density gradually increased and believed to be responsible for the J _c enhancement.     

Preparation and characterization of non-random YBa2Cu3O7-Ag composite

Silver addition to the highT _c superconductor, YBa₂Cu₃O₇ (YBCO) is known to improve its mechanical properties and critical current (J _c) characteristics. We have synthesized the superconductor-metal composite YBCO-Ag by an electroless process at room temperature (using sucrose or hydrazine hydrate in an alkaline medium). The latter method produces a non-random coating whereby each grain of YBCO is coated uniformly by silver. The intrinsic highT _c of 90 K of YBCO can be recovered by compaction of the composite and subsequent heat treatment (900°C and 600°C) in oxygen.     

Artificial in-plane ordering of textured YBa2Cu3O7?x films deposited on polycrystalline yttria-stabilized zirconia substrates

Anisotropie surface texturing of the polycrystalline yttria-stabilized zirconia substrates, prior to YBa₂Cu₃O_7–x film deposition, is shown to promote in-plane (basal plane) ordering of the film growth in addition to thec-axis texturing. TheJ _c 's of the films in the weak-link-dominated low-field regime are enhanced considerably, and this result is attributed to the reduction of weak links resulting from a reduction in the number of in-plane large-angle grain boundaries.The authors acknowledge the support and encouragement of V. G. Keramidas and P. L. Key. This work was supported by the Electric Power Research Institute (Contract No. RP 7911-13).     

REBa_2Cu_3O_(7-δ)系超导体的磁矩效应

本文研究了HoBa_2Cu_3O_(7-δ)系氧化物陶瓷超导体的生成工艺;着重探讨了磁场成形及磁场烧结对RE(RE=Y,Ho)Ba_2Cu_3O_(7-δ)系氧化物超导体的取向及超导性能的影响;并借助于X—ray衍射分析和SEM分析,从金属离子外层电子状态对结果进行了探讨、分析。     

静磁场下超导圆极化微带天线辐射性能研究

在液氦温度下，研究了工作频率为６．２６ＧＨｚ的Ｙ系超导圆极化微带天线的传输系数Ｓ２１及圆极化轴比随外加工磁场的变化，实验结果表明：在４．２Ｋ温度，外加磁场Ｂ≤１Ｔ时，其Ｓ２１及圆极化轴比基本不随外加磁场的变化而改变。     

An accurate method of iodometric titration to measure copper valence of high-T c superconductors

The double iodometric titration is the method widely used to determine copper valence of high-T _c superconductors. There are some problems that remain to be solved, and certain procedures are used: adding KSCN to release adsorbed iodine, adding HN₄HF₂ to eliminate the interference of some dopants, and using a new calculating equation to accurately calculate experiment results. Al- and Fe-doped samples were prepared and their copper valence, 2 +p, was determined by the improved double iodometric titration method. With these samples, how to use the above procedures to improve experiment results is discussed. We find that the iodometric titration method described here can be used to determine copper valence and oxygen content for doped and undoped samples with high accuracy.