Pellet‐buffered film seed to grow single grain bulk YBCO

Abstract

Epitaxial thin film seeds, exhibit a higher peritectic temperature than the bulk, have been recognized as a possible way to obtain large-sized single-grain REBCO bulks. Recently, use of a pellet as a buffer layer inserted between the film-seed and the main pellet has been reported. This approach can prevent Mg diffusion from the MgO substrate to the film seed, and enable the thin film to tolerate a higher maximum temperature in the TSMG (Top Seed Melt Growth) method.However, we found that the liquid phase decomposed from YBa 2-Cu 3 O 7Àx (YBCO) contacted the MgO substrate, due to surface tension, and caused undesirable grain nucleation. To resolve this problem, this study used a mini-pellet, smaller than the seed, as a buffer layer. This new technique can avoid the liquid phase contacting the MgO substrate, thereby allowing the YBCO single-grain bulk to be grown more easily. Moreover, the thin film seed can be re-used by removing the buffer layer after the crystal growing process.

Progress in Buffer-Supported Seeding Architectures for Reliable Epitaxial Growth of REBa2Cu3O7−δ Bulk Cryomagnets with Superior Properties

“…In addition, the geometry of a buffer layer was also found to have a substantial impact on the seeding of melt growth. , First, YBCO cylindrical buffers with five different aspect ratios ( R h/r ) varied from 3.0 to 1.1 were pressed to grow Nd123-crystal-seeded YBCO bulks . Random parasitic grains and irregular facet lines would not disappear until the R h/r decreased to 1.1.…”

“…Over the past decade, the buffer layer technology was greatly developed in TSMG by different groups, ,− demonstrating a variety of roles in the preparation of high-performance REBCO bulk superconductors. Here, its distinctive functions (as shown in Figure ) are summarized as follows.…”

Simulation and Observation of Magnetic Particles Captured in Fluids Using High Temperature Superconductor Bulk

“…In this paper, we attempted to build a mathematic model to calculate the trajectory of the magnetic particles and prove it by directly observing the trajectory of the particles under different magnetic situations. Also, to determine the effects of the magnetic field and field gradient, we used a permanent magnet (PM) and homemade high temperature superconductor bulk (HTS) [21], [22] as the magnetic source and compared our results with the simulation results.…”

Magnetic levitation force and trapped field properties of multiseeded YBCO with triangular arrangement of seeds

“…The researches have focused on improving the structural 16,17 and superconducting properties of MSMG samples such as critical current density, 16,18 magnetic levitation force (MLF), [18][19][20][21] and flux trapping capacity. 16,17,19,22,23 Although the MSMG method allow to produce large single-grain HTS samples within a reasonable time, it has some disadvantages due to the formed structural defects during the fabrication process.…”

“…The I G U R E 3 B x and B z Magnetic flux density distribution of the PMGmagnetic field was supplied by an electromagnet (GMW, Model 3473-70 electromagnet, Redwood City, CA). After removing the external magnetic field, the trapped field values were measured by a Hall probe (LakeShore, Model HGCA-3020, Westerville, OH) at 1.2 mm from the sample surface 22,23.…”