Research of the effective role of silver additions To YBa2Cu3O7

Abstract Metallic silver, or silver oxide, is more and more used to improve the properties of YBa2Cu3O7 ceramics. Increases of the current carrying capacity are thus commonly obtained, but the role of this silver addition has not yet been clearly explained. As it is generally considered that silver improves the connectivity between grains, we assumed that this improvement resulted of a chemical interaction between silver and the superconducting material. In order to check this asumption, we have studied the chemical reactions of silver with the phases possibly existing in a YBaCuO ceramic : starting reagents, secondary phases and the superconducting oxide itself. Results obtained show that silver reacts with barium based compounds (BaCuO2, BaCO3) and melts. This melting probably “cleans” the grain surfaces and increase their reactivity.