Hot seeding for the growth ofc-axis-oriented Nd-Ba-Cu-O

Abstract

The fabrication of large single-grain RE-Ba-Cu-O (RE denotes rare earth elements) is essential for bulk applications. In the present study, we report on a hot-seeding method for growing Nd-Ba-Cu-O with Nd123 seed crystals. We made an arrangement, in which the Nd123 seed crystal can be transported to the centre of the furnace with a rod through a hole in a rubber cork and insulating stopper. The seed was placed in a small dip made in the rod, which can be turned to drop the seed on the sample. The advantage of this method is that perturbation in the growth conditions such as temperature and oxygen partial pressure can be minimized. Using this method we could grow large single-domain c-axis-oriented samples with the surface area larger than 3 cm × 3 cm.

Use of <inline-formula> <tex-math notation="LaTeX">$\mbox{Sm}\text{-}123 + \mbox{Sm}\text{-} 211$</tex-math></inline-formula> Mixed-Powder Buffers to Assist the Growth of SmBCO and ZrO₂-doped SmBCO Single Grain, Bulk Superconductors

“…The top-seeded melt growth (TSMG) process with Mg-doped NdBCO generic seeds (MgO-NdBCO) is used commonly to fabricate SmBCO single grains with controlled orientation. However, due primarily to the high melting temperature, rapid growth rate and the need to process the material under reduced oxygen partial pressure to inhibit the substitution of Sm on the Ba site in the superconducting SmBa 2 Cu 3 O 7−δ (Sm-123) phase [4], it is extremely difficult to grow large SmBCO single grains in air with good superconducting properties, even without the addition of dopants.…”

Mg-doped Nd-Ba-Cu-O generic seed crystals for the top-seeded melt growth of large-grain (rare earth)-Ba-Cu-O bulk superconductors

“…The hot seeding process has been used to grow large single grains of various (LRE)BCO compositions with controlled orientation and good superconducting properties under a processing atmosphere of 1% oxygen in nitrogen. [11][12][13] Unfortunately, this technique requires specially designed furnaces that enable control of the processing atmosphere and placement of the seed at an elevated temperature. As a result, hot seeding cannot be adopted practically because of these processing complexities.…”

Fabrication of high performance light rare earth based single-grain superconductors in air

“…The former may be overcome partially by employing the so-called "hot" seeding process in which the premolten semiliquid precursor is seeded by a single crystal of the same composition ͑i.e., self-seeding͒. 7,8 The latter has been overcome to a limited extent by processing the bulk material under reduced oxygen partial pressure, 2,3 although this often results in the formation of SS at the initial stage of crystal growth. In view of the requirements for a controlled PO 2 and the lack of a suitable seed crystal, both of which represent real barriers to a practical fabrication process a practical method by which these materials can be fabricated reliably and economically in the form of large single grains has only been developed recently.…”