Mechanical properties of TSMG-YBCO

The fracture toughness, K/sub c/, of YBCO prepared by the top-seeded-melt-growth (TSMG) method can be improved by increasing the yttrium content. K/sub c/ increases from 1.01 MPa/spl radic/m for samples with 30 mol % Y/sub 2/Ba/sub 1/Cu/sub 1/O/sub 5/ (Y-211) addition to a value of 1.44(22) MPa/spl radic/m for samples with 60 mol % Y-211 addition. Substituting CeO/sub 2/ for PtO/sub 2/ results in a further enhancement of K/sub c/. In both cases the improvement can be explained by a refinement and homogenization of the distribution of Y-211 particles. The incorporation of ductile particles also contributes to an enhanced fracture toughness of the melt-textured monoliths.