Delamination behavior of Gd123 coated conductor fabricated by PLD

We have studied delamination behavior of GdBa₂Cu ₃O_7-d (Gd123) coated conductors fabricated by pulsed laser deposition. Two kinds of delamination tests, transverse tensile test and four points bending test, were performed. The delamination strength of 8 and 4-7 MPa was obtained by transverse tensile test, and interfacial cohesive energy of 7.1 and 5.9 J/m² was obtained by four points bending test for samples fabricated with different processing rates, 20 m/h and 60 m/h, respectively. EPMA and XPS analyses of delaminated surfaces showed that the weakest position in Gd123 coated conductor was inside of Gd123 layer a few nm apart from Gd123/CeO₂ interface. The samples exhibiting a lower interfacial energy had a large gradient in oxygen distribution at the interface. The reason why the delamination occurred there is due to strain concentration induced from both lattice mismatch and inhomogeneous oxygen distribution at the interface.