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The large-scale use of (RE)-Ba-Cu-O bulk superconductors, where RE=Y, Gd, Sm, is in part, limited by their mechanical properties. These materials belong to the ceramic family of compounds and so are inherently brittle. Alloying of (RE)-Ba-Cu-O with silver enables a significant improvement in the mechanical properties, without a detrimental effect upon the superconducting properties. However, the growth of large single grains, as are required for practical applications, is complex and includes many interacting variables. The addition of silver increases the complexity of the manufacturing process further, thus increasing the likelihood of failure of single grain growth.
A critical set of processing variables in the top seeded melt growth process are the times and temperatures in the heating profile which are required to grow single grains. The heating profile contains multiple stages and is influenced by the growth mechanism. The growth rate is important for study of the growth mechanism and enabling determination of a suitable heating profile. However, to date, the growth rate in the YBCO-Ag system has not been reported.
The liquid-phase enrichment technique has significantly increased the reliability with which fully grown single grains of YBCO exhibiting uniform superconducting properties can be produced. This technique has since been adapted to enable the growth of YBCO-Ag bulk samples. In this work we have successfully measured the growth rate of single grains in the YBCO-Ag system the first time. In addition, it has been seen from observation of the shape of the growth front and measurements of the growth rate that the growth process differs significantly between the YBCO and YBCO-Ag systems.