Papers by Author: I. Hamadned

Abstract: Longitudinal and shear ultrasonic attenuation measurements were performed at 10 MHz in HoBa2-xHoxCu3O7-δ (x=0.0 and 0.15) polycrystalline ceramics between 80 K and 285 K. Longitudinal attenuation profiles showed a large peak around 200 K for superconducting HoBa2Cu3O7-δ but not for oxygen-reduced non-superconducting HoBa2Cu3O7-δ. Two longitudinal attenuation peaks at 190 K and 250 K were observed for Ba-substituted HoBa1.85Ho0.15Cu3O7-δ. The high temperature (∼190 K-200 K) peaks are due to absorption of sound energy during interaction of ultrasound wave with mobile oxygen atoms involved in an oxygen rearrangement process involving Cu-O chains of the materials.