INTERNAL-FRICTION IN BI-SR-CA-CU-O GLASSES

The results of internal friction and d.c. conductivity measurements in Bi2O3-CaO-SrO-CuO glasses and partially crystallized glasses are repo rted. Furthermore, a comparison between the internal friction spectra of superconducting ceramics and those of copper phosphate glasses has been done. The internal friction measurements were performed by means of low frequency vibrating reed and torsion pendulum methods. A mechan ical loss peak observed at 150 K (at 200 Hz) in crystallized glass and bismuth superconducting ceramics can be correlated with the mechanism of the d.c. conductivity in crystallized glass. The comparable value of the relaxation parameters suggests the same mechanism to be respons ible for both processes. In the glassy state the internal friction pea k observed at about 275 K corresponds to the mechanism of small polaro n hopping between copper ions in different valency states (Cu-I-Cu-II) . The copper phosphate glass exhibits a mixed electronic-ionic behavio ur. The large internal friction peak in the high temperature region ca n be related to Cu-I ion and proton migration in the glass matrix.