Inter- and intra-grain microwave absorption in YBa2Cu3O7and Bi2Sr2CaCu2O8powders

Microwave absorption measurements, detected by a conventional ESR spectrometer, on YBa 2 Cu 3 O 7 and Bi 2 Sr 2 CaCu 2 O 8 powders confirm the distinct features of the signals by the inter- and intra-grain superconductive regions, already recognized in YBa 2 Cu 3 O 7 , but also show interesting differences between the two compounds, related to a much more limited role of the weak links and to a weaker pinning in the Bi-based compound.