Preparation and Properties of High-Quality Melt Growth Gd123 Bulks With Low Void Density: Flexural Strength at 77 K

Mechanical properties of melt growth GdBa₂Cu₃O_x (Gd123) large single domain superconducting bulks with Ag₂O of 10 wt% and Pt of 0.5 wt%; 30 mm in diameter and 15 mm in thickness with low void density were evaluated at 77 K through flexural tests of specimens cut from the bulks, and compared to those of a conventional Gd123 with voids. Gd123 bulks were prepared with a seeding and temperature gradient method; first melt processed in oxygen, then crystal growth in air; two-step regulated atmosphere heat treatment. We discuss mechanical properties; the flexural strength and Young´s modulus at 77 K. The results show that the flexural strength of the Gd123 at 77 K with low void density is 20 ~ 30% larger than that of a Gd123 conventional bulk which includes voids.