High-Energy Ultrasonication: Effective Way of Controlling the Growth and Superconducting Properties of Single Grain REBa2Cu3O7-δ Bulks

The fabrication of
RE
Ba
₂
Cu
₃
O
_7-
δ
(
RE
BCO,
RE
= rare earth elements) bulks in single grain form and their flux pinning depend strongly on the initial conditions of the
RE
₂
BaCuO
₅
(
RE
211) phase used as precursor. We recently demonstrated a novel method of employing high-energy ultrasonication to create fine
RE
211 particles (
RE
211
_Ultra
) with irregular shapes along with sharp edges and damaged surfaces. The developed method is convenient, free of contaminants, and low cost as compared to other methods currently utilized. Integrating these
RE
211
_Ultra
in the top-seeded melt growth (MG) method, we improved the initial peritectic growth reactivity and thus, the superconducting properties of YBCO and GdBCO bulk single grains. Melt growth experiments were carried out on different
RE
BCO (
RE
= Y and Gd) systems with the addition of 30 mol% of
RE
211
_Ultra
. The
RE
211
_Ultra
particles boosted the initial peritectic reaction i.e., growth rate during the MG process due to their sharp edges, and damaged surfaces in their nanometer size. The left-back fine-sized
RE
211 particles increased the interfacial defects and hence, the flux pinning. In the present work, we summarize the effect of ultrasonication of
RE
211 particles, their impact on peritectic reaction and improvement of superconducting properties of various REBCO bulks. Employing
RE
211
_Ultra
powders for infiltration growth (IG) processing, we enabled a good control of the
RE
211-phase content and particle size in the final bulk YBCO single grains. The field-dependence properties of MG and IG-processed of YBCO superconductors are significantly improved without any additional chemical addition/doping.