(a) A failed YBCO bulk grown from homemade powders. (b) The corresponding recycled bulk processed at Tmax of 1105 °C with a NdBCO/YBCO/MgO film seed.
(a) A recycled bulk using a Tmax of 1115 °C. (b) A schematic of different positions within the recycled single domain from which specimens were cut. (c) The normalized magnetization of the specimens as a function of the temperature in an external field of 20 Oe.
(a) Heating profiles corresponding to the three different types of failed REBCO bulks. Schematic cross-sections for the three kinds of failed bulks are attached to their corresponding heating profiles. TE: the equilibrium temperature; TMeta: the critical temperature between metastable and unstable statuses. The inset in (a) is a schematic illustration showing a typical heating profile of REBCO in the MT growth. T1 and T2 are the temperatures at which the slow cooling begins and ends, respectively. (b) A two-dimensional map of MT-processed REBCO bulk types corresponding to the liquid phase statuses at the stage between T1 and T2, in terms of temperature and supersaturation. The “stable” region yields no nucleation or growth. The “metastable” region leads to the seed-induced growth. The “unstable” region results in the self-nucleation. The ellipses schematically refer to the liquid phase status at the slow cooling stage, i.e., temperature changing from T1 to T2, for the three kinds of wrong-processed REBCO bulks and a typical perfect bulk.
(a) A type III failed YBCO bulk grown from commercial powders. (b) The corresponding recycled bulk grown with Tmax of 1115 °C using a NdBCO/YBCO/MgO film seed.
Three types of failed REBCO bulks resulting from different non-optimized heating profiles. TE: the equilibrium temperature; TMeta: the critical temperature between metastable and unstable statuses.
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