Enhanced Growth Rate of a YBCO Bulk in the Melt-Textured Process Under 1 atm Oxygen Pressure

Abstract

By the employment of 1 atm oxygen pressure as the growth atmosphere, we report a success in the enhanced growth rate of the melt-textured (MT) YBCO bulk. A well-oriented c-axis single-domain bulk with a size of 42 mm in diameter was fully grown at a high average growth rate of about 0.32 mm/h, which is 1.5 times larger than that in air. It was found that the increased oxygen partial pressure has a profound influence on the MT growth (MTG) for YBCO. The enhanced growth rate can be interpreted by both increased solubility and diffusion coefficient of yttrium in the Ba-Cu-O liquid under high oxygen partial pressure. After oxygenation, single-domain samples were determined to have a sharp superconducting transition temperature at 91.7 K, indicating that the superconductivity of crystals grown under high oxygen pressure does not degrade. Additionally, due to the rapid growth, the trapping effect of Y211 particles becomes predominant. As a result, a relatively more homogeneous distribution of Y211 particles was observed in the Y123 matrix. Finally, the most important advantage of this technique is that the enhanced growth rate of Y123 gives less opportunity from self-nucleation in the liquid, which takes place beyond the growth window and the embryonic period. Thus, this oxygen-increased MTG process is very promising for producing large-sized YBCO bulks with good superconducting properties.Index Terms-Enhanced growth rate, melt textured (MT), 1 atm oxygen pressure, YBCO bulk.

Large Size and High Performance of a Gd–Ba–Cu–O Bulk Superconductor Grown Using New Approaches

“…The results are in agreement with the interpretation developed earlier that the range of RE/Ba substitution in GdBCO is smaller than in other (LRE)BCO, such as SmBCO and NdBCO materials, as the Gd 3+ ion is smaller than Sm 3+ or Nd 3+ ions 13 . On the other hand, it has been reported that the average growth rate of MT in a pure oxygen environment can be enhanced by >0.5 times for YBCO, which can be explained by the increase of both the solubility and the diffusion coefficient of yttrium in a Ba–Cu–O liquid under a high oxygen partial pressure 25 . It can be deduced further that the growth rate of GdBCO bulks can be increased in pure oxygen in comparison with that in air.…”

Peritectic melting of thin films, superheating and applications in growth of REBCO superconductors

“…Furthermore, the oxygen controlled melt growth process is generally utilized to suppress the RE/Ba substitute in LREBCO 7Ày (LRE = Gd, Sm, Nd) system, which deteriorates the superconducting property [70]. In addition, the growth rate of REBCO bulks in an elevated oxygen pressure is higher than that in air [71]. With respect to the thermal stability of REBCO system, the oxygen affects the solubility of RE elements in the liquid and the t.c.s.…”

Comparison Between Modeling and Experimental Results of Magnetic Flux Trapped in YBCO Bulks

“…T ARGETING practical applications of High-Temperature Superconducting (HTS) bulks [1]- [3], a great deal of effort has been carried out regarding the art of growing materials, their properties and their modelling [4]- [7]. With regards to the latter, analytical formulae, in the simplest 2D cases using the Bean's Critical State Model (BCSM), and numerical models, in the most complex geometries involving 3D modelling techniques and/or more refined critical current dependencies, have been developed to predict the magnitude of the penetration field and the feasibility of trapping large magnetic fluxes [8]- [10].…”