Ferroelastic detwinning of the high-temperature superconductor YBa₂Cu₃O_7-δ

Abstract

Crystals of YBa₂Cu₃O_7-δ (YBC) were prepared using a flux technique. The as-grown crystals were typically on the order of 200 μm × 200 μm × 50 μm, where the 50 μm dimension is in the c-direction. Ferroelastic behavior was observed by applying a uniaxial stress along the [100]_tet-direction using a specially-designed fixture which was mounted to a programmable hot/cold stage of a polarizing reflected-light microscope. Domain wall motion was observed for temperatures greater than 200°C, and complete poling was accomplished at stresses on the order of 50–100 MPa at temperatures of 350–400°C. An ionic diffusion-activated mechanism is suggested.

Key Words:

• Superconductor
• YBa₂Cu₃O_7-δ
• YBC
• ferroelasticity
• ferroelastic detwinning
• ferroelastic poling
• ferroelastic domains
• crystal growth