Effect of Y-211 particle size on the growth of single grain Y–Ba–Cu–O bulk superconductors

• Published in: Journal of crystal growth Vol. 412; pp. 31 - 39
• Main Authors: Thoma, Max, Shi, Yunhua, Dennis, Tony, Durrell, John, Cardwell, David
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.02.2015
• Subjects: A1. Fine Y-211 particle size; A1. Liquid loss; A2. Heating profile; A2. YBCO single grain growth; COPPER OXIDE; CURRENT DENSITY; Grain growth; Grains; Inclusions; PARAMETERS; Particle size; PARTICLE SIZE AND SHAPE; Precursors; Process parameters; SUPERCONDUCTORS; YBCO superconductors; Yttrium; YTTRIUM OXIDE; A1. Liquid loss; A2. YBCO single grain growth; A1. Fine Y-211 particle size; A2. Heating profile
• ISSN: 0022-0248; 1873-5002
• DOI: 10.1016/j.jcrysgro.2014.11.037

The engineering of fine Y2Ba1Cu1O5 (Y-211) inclusions of average particle size 1−2μm within the continuous, superconducting YBa2Cu3O7−δ (Y-123) phase matrix of single-grain, bulk high temperature Y–Ba–Cu–O (YBCO) superconductors is fundamental to achieving high critical current density in these materials. However, bulk samples fabricated using fine Y-211 precursor powders generally suffer from incomplete growth of the Y-123 phase compared to samples fabricated with coarser Y-211 particles of average particle size >5μm in the precursor powder. In this study, the effects of Y-211 particle size on processing parameters during growth of large single YBCO grains are reported. Chemical analysis using EDX of cross-sections of single YBCO grains indicates that the loss of liquid phase during melt processing is greater when finer Y-211 precursor powder is employed, which accounts for the observed growth limitations and low sample yield. Specific modifications to the single grain growth process have been made based on the results of this investigation to reduce liquid loss and to enable the use of fine Y-211 precursor powder without compromising complete single grain growth or yield. •The effects of Y-211 particle size on growth parameters of YBCO grains are reported.•Samples using fine Y-211 powders grow faster and experience more liquid loss.•Liquid loss is one of the reasons for incomplete sample growth.•EDX revealed changes in chemical composition during growth from solid samples.•Modifications to the growth process have been made to achieve complete sample growth.