Title: Y211 particle refinement in YBCO bulk superconductors by CeO₂ addition

Authors: Pavel Diko, Martina Sefcikova, Katarina Zmorayova, Vitaliy Antal

Addresses: Institute of Experimental Physics, Slovak Academy of Sciences, Watsonova 47, 04353 Kosice, Slovakia. ' Institute of Experimental Physics, Slovak Academy of Sciences, Watsonova 47, 04353 Kosice, Slovakia. ' Institute of Experimental Physics, Slovak Academy of Sciences, Watsonova 47, 04353 Kosice, Slovakia. ' Institute of Experimental Physics, Slovak Academy of Sciences, Watsonova 47, 04353 Kosice, Slovakia

Abstract: The influence of preparation parameters as nominal composition (Y₂O₃ and CeO₂ additions), particle size of starting Y123 powder, milling and mixing conditions and sintering temperature on the refinement of Y₂BaCuO₅ (Y211) particles in the single-grain YBa₂Cu₃O₇/Y₂BaCuO₅ (Y123/Y211) bulk superconductors prepared by top-seeded melt-growth process has been studied. The microstructure was analysed after sintering and melt processing by polarised light microscopy and electron microscopy. It is shown that cerium is active in the Y211 particle refinement when it is solved in the peritectic melt, L_p. When cerium is present as barium cerate, it has no refining effect. The addition of CeO₂ and barium cerate formation even leads to a faster growth of Y211 particles at the sintering stage due to intensive melt production. Refinement of Y211 particles in the samples with large Y123 particles is related to the formation of very dense Y211 skeleton which is resistant to melt formation at the sintering stage. Critical current density of these single-grain bulk superconductors is significantly influenced by final microstructure.

Keywords: bulk YBCO superconductors; microstructure; CeO2 addition; Y211 refinement; cerium; particle size; milling; mixing conditions; sintering temperature; barium cerate; yttrium barium copper oxide.

DOI: 10.1504/IJMPT.2011.039932

International Journal of Materials and Product Technology, 2011 Vol.40 No.3/4, pp.215 - 225

Published online: 28 Feb 2015 *

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