Comparison of acoustic properties of ceramics Cu O and YBa2 Cu3 Ox in the 5-310 K temperature range

The comparative study of ultrasound absorption and velocity of ceramic samples Cu O and YBa2 Cu3 Ox (x=6.95 and 6.93) is made in temperature range 5-310 K and the frequency interval 47-370 khz. It is shown that the ultrasound absorption on spectra of Cu O and YBa2 Cu3 Ox are similar in the temperature intervals 30-60 and 235-250 K. In these regions they involve absorption peaks P1 and P4, the behavior of which with variations in frequency is identical for both the compounds. The absorption on spectra of Cu O and YBa2 Cu3 Ox are most different in the temperature range 100-200 K. The spectrum of Cu O does not contain peaks P2 and P3 typical of the ceramics YBa2 Cu3 Ox. The temperature dependence of sound velocity are investigated in the ceramics Cu O for the first time. The hysteresis similar to that in YBa2 Cu3 Ox is observed under cycling. The hysteresis existence in Cu O and tetragonal sample of YBa2 Cu3 Ox does not agree with the concept of tis twinning nature. Some phase transition seems to take place and the hysteresis is supposed to be due to the development of a low-temperature phase domain structure