Anomalous thermal expansion behaviors in Sm-Ba-Cu-O superconductors

Linear thermal expansion coefficients alpha of c-axis oriented Ag-added Sm- Ba-Cu-O superconductors have been measured in the range of 10 - 300 K. The a showed a large bump along the c-axis and a large dent along the ab-plane around 170 - 260 K for the 2 wt% and 5 wt% Ag2O specimens, but these anomal ies essentially disappeared with thermal cycles between room and cryogenic temperatures. In contrast, there were no significant anomalies for the 10 w t% and 20 wt% Ag2O specimens. These results suggest that the addition of Ag 2O should moderate deformation and help to increase mechanical strength.