关键词: 单畴GdBCO超导块材/
磁悬浮力/
捕获磁通密度/
临界温度
English Abstract
Influences of BaO doping on the properties of singe domain GdBCO bulk superconductors
Wang Miao1,Yang Wan-Min2,
Yang Peng-Tao2,
Wang Xiao-Mei1,
Zhang Ming1,
Hu Cheng-Xi1
1.School of Science, Xi'an Aeronautical University, Xi'an 710077, China;
2.School of Physics and Information Technology, Shaanxi Normal University, Xi'an 710062, China
Fund Project:Project supported by the National Natural Science Foundation of China (Grant No. 51572164), the Keygrant Project of Chinese Ministry of Education (Grant No. 311033), and the Scientific Research Project of Xi'an Aeronautical University, China (Grant No. 2016KY1213).Received Date:02 July 2016
Accepted Date:19 August 2016
Published Online:05 November 2016
Abstract:In this work, a series of single domain GdBCO bulk superconductors with different ratios of BaO addition in the solid phase pellet, is successfully fabricated to inhibit the Gd/Ba substitution in the growth process by the modified top seeded infiltration growth (M-TSIG) technique. The reaction of the precursor powders, the growth morphology, the magnetic levitation force (F), the trapped magnetic flux (Btr) and critical temperature (Tc) of the single domain GdBCO bulk superconductors are investigated in detail. First, the differential thermal analysis is performed on the precursor powders of 10 mg solid phase pellet (containing various amounts of BaO) and 15 mg liquid phase pellet in order to investigate the melting temperature (Tm) and the peritectic temperature (Tp) of the GdBCO superconductor system. The results show that the melting point of the precursor powder decreases by nearly 8℃ as the BaO composition increases from 0 wt% to 4 wt%, which leads to Tp decreasing with BaO content increasing. Second, the top view morphologies of the GdBCO samples are also discussed. All of the samples exhibit clear, fourfold growth sector boundaries on their top surfaces, and spontaneous satellite grains are observed in none of these samples. It can be seen that the different ratio of BaO addition cannot affect the growth morphology of the single domain GdBCO bulk superconductor. And thirdly, the levitation force and trapped field of each of the samples are measured under a zero field cooling state at 77 K by the three-dimensional magnetic force and field device. The values of the levitation force for the samples are slightly different for different ratios of BaO additions. The largest levitation force is 35 N, which is obtained in the sample with 2.5 wt%, and the smallest one is 28 N in the sample with 1 wt% BaO addition. And also, the trapped field of the sample can be attributed simply to the variation in the pinning strength. It can be obviously seen that these values fluctuate between 0.28 T and 0.32 T for these samples. Finally, the critical temperatures of the samples are measured by the vibrating sample magnetometer with an external magnetic field of 0.01 T. The samples exhibit outstanding features of high Tc, which indicates that these samples are of good quality and the Gd/Ba substitution is inhibited by the BaO addition. The above results show that the values of melting temperature (Tm) and peritectic temperature (Tp) of the samples have the decrease tendencies, and the superconducting properties of the samples (such as F, Btr and Tc) can be improved to a certain extent when the amount of BaO added ranges from 2 wt% to 4 wt%, which are very helpful in inhibiting the Gd/Ba substitution and fabricating the high-quality single domain GdBCO bulk superconductors.
Keywords: singe domain GdBCO bulk superconductor/
levitation force/
trapped flux field/
critical temperature
