Elastic study of quench and composite europium barium copper oxide (EuBa2Cu3O7-δ(Eul23)) superconductor / Siti Noorzuraidah Jusoh.

Ultrasonic longitudinal and shear velocities at 9MHz were measured using pulse-echo overlap techniques in temperature ranges of 80-280K and 80-220K, respectively, in EuBa2Cu3O7-δ +ywt.% AI2O3 (y = 0, O(quenched), 0.2 and 0.4) superconductors. A steplike elastic anomaly indicating sudden lattice stiffening was observed for x=0 at around 260K. However upon quenching to reduce the oxygen content, no anomaly was observed and only a monotonous change in velocity with increasing temperature was observed. Addition of AI2O3 only shifted the anomaly to slightly lower temperatures. The step-like elastic anomaly was discussed in terms of oxygen ordering involving Cu-O chains.