The development of melt-processed (Sm,Eu,Gd)Ba₂Cu₃O_7−δ single-domain superconductors for high field applications

Abstract

(Sm,Eu,Gd)Ba2Cu3O7−δ (RE123) single-domain superconductors were grown in 1% O2 in Ar with a modified hot-seeding melt process. Spatial superconducting variation and a local RE–Ba modulation were suppressed with the control of processing conditions. Pre-annealing at 960 °C for 10 h in Ar prior to melt growth was found to significantly lower the range of RE–Ba substitution and diminish the number of pores and microcracks. Excess BaCuO2−x was added to induce a Ba-enriched liquid and thereby hinder the nucleation of RE1+xBa2−xCu3O7−δ solid solution (RE123ss). The proper ratio of BaCuO2−x to RE123 was around (0.17–0.25):1. The optimal thermal schedule was a fast cooling with a rate of 2 °C h−1 for 10 h followed by a 100 h slow cooling of 0.15 °C h−1. A field of 1 T was trapped in a pellet of 35 mm diameter at 77 K and 2 T, which corresponded to the maximum external flux density of 3 T including the bias applied field.

Hall probe mapping of melt processed superconductors with artificial holes

“…In particular, macrocracks that may result from residual mechanical stresses or from impurity phases [1,2] and that are oriented parallel to the c-axis significantly affect the supercurrent flow and consequently the maximum achievable trapped fields. During the past few years, the cracking problem in melt grown superconductors based on the brittle compound YBa 2 Cu 3 O 7−δ (YBCO) in the context of the oxygenation treatment has been discussed in more detail in the context of the oxygenation treatment [3][4][5].…”

Recent progress on compositional nanostripes of REBa2Cu3O7−δ(RE = Sm,Eu,Gd) superconductors

“…GdBa 2 Cu 3 O 7−δ single domains with a nominal composition of GdBa 2 Cu 3 O 7−δ + 0.4Gd 2 BaCuO 5 + 0.1BaCuO 2−x were processed in 1% O 2 in Ar [18]. (Sm 0.33 Eu 0.33 Gd 0.33 )Ba 2 Cu 3 O 7−δ single domains with a nominal composition of GdBa 2 Cu 3 O 7−δ + 0.4Gd 2 BaCuO 5 + 0.1BaO 2 were processed both in air and in 1% O 2 /Ar [19]. For all these melt-processed crystals, 10 wt% Ag 2 O and 0.5 wt% Pt were added to the initial composition in order to improve the mechanical properties and hinder the coarsening of RE 2 BaCuO 5 secondary phase particles.…”

Nanostripes in superconducting REBa 2 Cu 3 O 7 -δ superconductors: robust vortex pinning sites

“…Melt-processed (Sm 0.5 Eu 0.5 )Ba 2 Cu 3 O 7-δ crystals were grown in 1%Ar in O 2 flow. 11 The initial composition was controlled. TEM samples were prepared by Ar ion milling.…”