Improvements in obtaining YBCO single domains using the partial melting zone method

Abstract

Longitudinal samples with additions were textured using the partial zone melting method. The experimental procedures developed to obtain large single domains are discussed. The liquid migration produced by capillary absorption during the thermal texturing hinders the stable and continuous solidification process. In this work different methodologies for avoiding this migration are discussed and compared. The present study proposes an interpretation of the mechanism of the natural single-domain selection. The angle between the a- b plane and the sample axis has been found to be between and . This result and the shape of the solidification front are interpreted in the light of the above-mentioned mechanism. To make the a- b plane as parallel as possible to the longitudinal axis, experiments using YBCO seed were done and the results show that the final orientation is more parallel to the axis. So, this work shows that Y123 itself can also be used as seed for solidifying YBCO textured samples.

Texture analysis and microstructural features in YBa2Cu3O6+x zone-partial-melted samples with Y2BaCuO5 additions

“…Nakamura et al 19 and Imagawa and Shiohara 20 suggest that the crystals that have the direction of maximum growth rate parallel to the pulling direction can grow faster than others, because they need less supersaturation or undercooling. 12 The size of the Y211 particles in the final microstructure is related to the coarsening by an Ostwald ripening process at the time of partial melting, so small particles will go into solution and reprecipitate out onto larger Y211 particles. On the other hand, Müller and Freyhardt 21 discuss two collateral domains whose maximum growth rate direction is parallel or perpendicular to the pulling rate.…”

From RE-211 to RE-123. How to control the final microstructure of superconducting single-domains

“…The microstructure of single-domain (RE)BCO superconductors is highly dependent on the processing conditions and the presence or not of additives [19,27,[30][31][32][33][34][35][36]. A variety of meltprocessing techniques has been developed to produce singledomain (RE)BCO superconductors [11,18,[37][38][39][40][41][42][43][44][45]. All these techniques are based on the peritectic reaction 2(RE)Ba 2 Cu 3 O 7−δ(s) → (RE) 2 BaCuO 5(s) + Ba 3 Cu 5 O 8(l) + yO 2(g) .…”

Texture Investigation of Zone-Melted NBCO Superconductor Using EBSD Technique

“…Optimal performances can only be achieved in such NBCO samples with a well-textured microstructure. The partial zone-melting technique seems to be one of the most appropriate methods for obtaining textured NBCO samples [2]. For Nd-Ba-Cu-O system, zone-melting process takes place by moving a sample through a narrow hot zone with a thermal gradient.…”