Comparison study of the flux pinning enhancement of YBCO superconductor with BZO and BZO + Y2O3 mixed phase additions (original) (raw)
Related papers
Enhanced Flux Pinning Properties of YBCO Thin Films With Various Pinning Landscapes
IEEE Transactions on Applied Superconductivity, 2017
Pinning enhancement for YBa 2 Cu 3 O 7 −δ (YBCO) thin films is critical for their future applications such as superconducting cables, generators, and motors. In this study, several pinning landscapes are introduced and compared for improving the superconducting properties of YBCO thin films. First, BaZrO 3 (BZO) nanoparticles have been doped into YBCO matrix providing uniform defect pinning centers and resulting in the superconducting property enhancement. Second, a magnetic nanocomposite of (La 0 .7 Sr 0 .3 MnO 3 (LSMO)) x (CeO 2) 1 −x (with compositions of LSMO and CeO 2 varied from 50:50 to 70:30) has been incorporated into YBCO as either a cap layer or a buffer layer. Using this approach, both magnetic pinning and defects pinning are introduced in the systems. Third, multilayers of (LSMO) 0 .5 (CeO 2) 0 .5 /YBCO have been deposited to achieve uniform defect and magnetic pinning effects through the film thickness. The superconducting properties (critical temperature T c , and especially the critical current density J c) are compared for all the YBCO films with different pinning landscapes, and the corresponding pinning mechanisms are also discussed for each case. It is found that the pinning effect of YBCO film with magnetic nanocomposite layer is more significant under lower applied field, compared to the BZO-YBCO film. Through this comparison study, optimum pinning landscapes with combined defects and magnetic pinning approaches are proposed.
IEEE Transactions on Applied Superconductivity, 2017
Addition of nanophase defects to YBa Cu O (YBCO) superconductor thin films enhances flux pinning, resulting in an increase in transport current densities (Jct). While previous studies focused on single-phase additions such as BaSnO3, BaZrO3, and Y2BaCuO5 (Y211); the addition of several phases simultaneously has shown strong improvements by combining different flux pinning mechanisms. This paper further explores and compares the effect of mixed phase nanoparticle pinning, with the addition of insulating, nonreactive phases of: 1) BaSnO + Y O , 2) BaSnO3 + Y211, 3) BaZrO3 + Y O , and 3) BaHfO3 + Y O. Processing parameters vary the doped YBCO single target volume percent of either BaHfO3, BaSnO3, or BaZrO3, while maintaining either Y2O constant at 3 vol. %. Pulsed laser deposition produces films on LaAlO and SrTiO substrates at deposition temperatures of 750-840 °C. Current density is measured for fields ranging from H = 0-9 T with H // c, and temperatures from 5-77 K, providing a detailed picture of pinning effects. Optimized results of flux pinning, magnetic current densities Jcm (H, T), critical transition temperatures (Tc), lattice parameters, and microstructures are presented. The temperature dependence of the current density, Jc(T), is mathematically modeled to compare the isotropic weak and anisotropic strong pinning contributions, for each of the mixed phase systems studied.
Superconductor Science and Technology, 2005
Nanodot arrays of Y 2 O 3 were dispersed in thin films of YBa 2 Cu 3 O 7−δ (YBCO) by growing alternating layers of these two species using a pulsed laser deposition method. As a result, critical current density J c both in applied magnetic field and self-field is enhanced by as much as an order of magnitude, along with a significant increase in the irreversibility field H irr . High-resolution scanning transmission electron microscopy (STEM) and Z -contrast STEM show that the nanoparticles are crystalline and coherent with the YBCO matrix. Whereas in most other studies pinning has been attributed to the strain fields around the nanoparticles, in this case pinning may actually be due to the nanoparticles themselves, since the delineation between the two species is very sharp and STEM reveals no discernible strain fields in the superconducting material around the nanoparticles.
Preparation of YBCO-BYTO and YBCO-BZO nanostructured superconducting films by chemical method
Journal of physics: Conference Series, 2017
YBCO-BYTO6% and YBCO-BZO10% YBa 2 Cu 3 O 7-d-Ba 2 YTaO 6 6% (YBCO-BYTO6%) and YBa 2 Cu 3 O 7-BaZrO 3 10% (YBCO-BZO 10%) nanostructured films were grown by the Chemical Solution Deposition method, and compared with YBCO pure films. Films were deposited on YSZ substrates, with Ce 0.9 Zr 0.1 O 2 and Ce 0.6 Zr 0.4 O 2 buffer layers. They were characterized by GADDS X-ray diffraction, scanning electron microscopy (SEM) and inductive (SQUID) measurements of the critical temperature (T c) and critical current density (J c). It was found that YBCO-BZO10% films presented better superconducting properties (T c =89.2K and J c =1.3MA/cm 2), probably due to an enhanced pinning force, originated by BZO nanoparticles. Additionally, it was found that these films have lower reactivity with the buffer layer.
Applied Physics Letters, 2009
We have formed BaZrO 3 nanocolumns and ͑Gd, Y͒ 2 O 3 nanoprecipitates in reel-to-reel metal organic chemical vapor deposition ͑MOCVD͒ processed ͑Gd, Y͒Ba 2 Cu 3 O 7−x coated conductors and increased the critical currents ͑I c ͒ of the conductors in applied magnetic fields to remarkable levels. A ͑Gd, Y͒Ba 2 Cu 3 O 7−x tape of 1 m in length with 6.5% Zr-additions and 30% composition rich in both Gd and Y showed I c values of 813 A/cm width at ͑self-field, 77 K͒ and above 186 A/cm width at ͑1 T, 77 K͒. The strongly enhanced flux pinning over a wide range of magnetic field orientations can be attributed to the bidirectionally aligned defect structures of BaZrO 3 and ͑Gd, Y͒ 2 O 3 created by optimized MOCVD conditions.
Effects of Yttrium Oxide Inclusions on the Orientation and Superconducting Properties of YBCO Films
2013
The formation of Y2O3 secondary phase in the films of YBa2Cu3O7 (YBCO) high-temperature superconductor is of large interest because Y2O3 inclusions can increase the critical current density (Jc) in YBCO films. We studied Y-rich and Y-poor YBCO films prepared by the MOCVD method. Y2O3 phase appeared in the Y-rich films as small (20x10 nm) oriented particles distributed throughout the YBCO films. It was found that at the same growth conditions Y-rich YBCO films grew highly c-oriented, whereas in the Y-poor films both aand c-oriented YBCO grains were present. The Y-rich films exhibited better superconducting properties (Jc) because of better YBCO texture and magnetic flux pinning on the Y2O3 inclusions.
Nano Techniques for Enhancing Critical Current in Superconducting YBCO Films
Journal of Superconductivity and Novel Magnetism, 2011
A range of nano techniques is explored in order to increase the critical current in pulsed laser deposited (PLD) superconducting YBa 2 Cu 3 O x (YBCO) thin films. The structural measurements are linked with magnetic and transport measurements of the films. The effectiveness of PLD techniques is analyzed from the point of view of the dimensionality of nanostructures formed prior to and during the film growth. It is shown that a combination of twodimensional substrate decoration with nanoparticles before the film deposition and one-dimensional growth of external phase nanorods during the deposition offers a high critical current in magnetic field both along the c-axis and in the ab-plane of YBCO.
Physica C: Superconductivity, 2014
For practical applications of superconducting materials in applied magnetic fields, artificial pinning centres in addition to natural ones are required to oppose the Lorentz force. These pinning centres are actually various types of defects in the superconductor matrix. The pinning centres can be categorised on their dimension (volume, surface, or point) and on their character (normal cores or Dj cores).
Journal of Magnetism and Magnetic Materials, 2010
Magnetization studies of YBCO:BaZrO 3 composite superconductor have been done over a wide range of temperature and applied magnetic field using MPMS SQUID VSM and the results are compared with that of pure YBCO. The analysis of the observed results indicate that there is considerable improvement in the values of critical current density (J C) and pinning force density (F p) of YBCO:BaZrO 3 composite samples as compared to pure YBCO sample in the entire investigated range of applied magnetic field and temperatures ranging from 4 to 77 K. The variation of J C with reduced temperature t (¼T/T C) for the composite samples has been found to be similar to that of pure YBCO sample indicating similar nature of the vortex interaction with pinning centres in both pure and composite samples. The enhancement in the value of J C and F p in the composite samples as compared to pure YBCO sample has been attributed to the increased defect density in the composite samples due to the presence of BZO particles in YBCO matrix.
Strong isotropic flux pinning in solution-derived YBa2Cu3O7−x nanocomposite superconductor films
Nature Materials, 2007
Power applications of superconductors will be tremendously boosted if an effective method for magnetic flux immobilization is discovered. Here, we report the most efficient vortex-pinning mechanism reported so far which, in addition, is based on a low-cost chemical solution deposition technique. A dense array of defects in the superconducting matrix is induced in YBa 2 Cu 3 O 7−x −BaZrO 3 nanocomposites where BaZrO 3 nanodots are randomly oriented. Non-coherent interfaces are the driving force for generating a new type of nanostructured superconductor. Angle-dependent critical-current measurements demonstrate that a strong and isotropic flux-pinning mechanism is extremely effective at high temperatures and high magnetic fields leading to high-temperature superconductors with record values of pinning force. The maximum vortex-pinning force achieved at 65 K, 78 GN m −3 , is 500% higher than that of the best low-temperature NbTi superconductors at 4.2 K and so a great wealth of high-field applications will be possible at high temperatures.