Improved compositions for melt processing

Abstract

Melt texture processing of YBa 2 Cu 3 O y is limited by the slow cooling rate and the high temperatures required. Changing the rare earth can improve the processing conditions. The melting point of YbBa 2 Cu 3 O y can be reduced below the melting point of silver by adding silver, Yb 2 BaCuO 5 and/or reducing the oxygen partial pressure. The recrystallization rate of NdBa 2 Cu 3 O y + 0.2Nd 4 Ba 2 Cu 2 O 10 is shown to be extremely rapid. For low values of x , solid solutions of (Yb 1−x Nd x )Ba 2 Cu 3 O y may be able to be melt processed rapidly below the melting point of silver.

Texturing of high-Tcsuperconductors

“…Substituting yttrium by neodymium or ytterbium, Woolf et al [132] obtained spectacular recrystallization rates. With these systems which present quite acceptable critical temperature (T c for Nd123 ≈ 94 K, T c for Yb123 ≈ 90 K), Salama [130] was able to texture bars of Nd123 samples and coated Au wires of Yb123 at rates as high as 50 mm h −1 , and it seems that the texturing of these 123 compounds can be processed at rates as high as 100 mm h −1 .…”

Recent developments in melt texturing of 123 compounds

“…Together with the problem of grain boundaries, another problem associated with the conventional melt texturing techniques is long processing times. Recently, it was found that RE-123 type compounds with RE = Nd and Yb have a very high rate of recrystallization [13]. The high rate of recrystallization causes the recombination and solidification rates to increase significantly, thus making these compounds highly suitable for the directional solidification process.…”