Additional effect of Ag and 211 phase on thermal expansion of REBaCuO bulk superconductor (RE=Sm, Y) Original Research Article

The anisotropic thermal expansion ΔL/L was examined for melt-processed REBaCuO(Ag) bulk composites (RE=Sm, Y) as functions of not only the contents of the RE2BaCuO5 second phase but also Ag metal added to the highly oriented REBa2Cu3O7 matrix. The ΔL/L|c values in the c-direction of REBaCuO(Ag) bulks are about 1.5–1.8 times as large as the ΔL/L|ab values in the ab-plane. ΔL/L increases with increasing Ag content in both directions but ΔL/L|c is by far more sensitive to the Ag content. The resultant compressive strain due to Ag particles in the c-direction through the melt-processing was estimated and its possible contribution for the improvement of the superconducting characteristics of the matrix was discussed.