SUBSTRATE FILM INTERACTIONS IN THICK-FILMS OF YBACUO ON ALUMINA

The substrate-film interaction in thick films (>10 μm) of YBa2Cu3O7-x on alumina processed under normal conditions is investigated using electron-probe microanalysis. The formation of a mixture of barium aluminate and alumina over a thickness of about 2 μm in the interfacial region is established quantitatively using compositional mapping and point-count analysis across the substrate-film interface. Diffusion of aluminium into the film over several μm beyond the reaction layer is also observed. The variation of oxygen composition across the interface has been mapped. Leaching of oxygen from the 1-2-3 phase in the bulk is suggested as the reason for the observed decrease in Tc(0) and increase in ΔTc in films of YBa2Cu3O7-x on alumina. © 1990 Chapman and Hall Ltd.