Stable Conductive Contacts to High Critical Temperature Superconducting Oxides

摘要

The objective of the research was to show that conductive oxides such as Sn02 or Ti02, appropriately doped, can be used as contacts to high temperature superconducting materials. Y-Ba-Cu-O and Bi-Ca-Sr-Cu-O films were deposited on top of and underneath the conductive oxides. After sintering, tin diffused into the bismuth compounds preferentially replacing calcium and strontium. Tin also diffused into the 1-2-3 compounds but without preferential replacement. Titanium diffused into the 1-2-3 compound preferentially replacing copper. Contact resistances could not be measured as diffusion of the tin or titanium prevented the superconducting transition. TiO2, when deposited on top of Bi-Ca-Sr-Cu-O, acted as a partial diffusion barrier to degradation in water. The research suggests that different contact and diffusion barriers are needed for each of the major classes of high temperature superconducting compounds.