Twin Domain Fragmentation in YBa2Cu3O7-δ Under Electron Irradiation

Detwinning and retwinning processes in the orthorhombic YBa2Cu3O7-δ have been directly observed under appropriate electron irradiation by transmission electron microscope. These processes can be repeated many times and are accompanied by twin domain fragmentation and appreciable increase of twin interface density, which is a potential pinning center in YBa2Cu3O7-δ. The meaning of this effect in raising Jc of the material YBa2Cu3O7-δ is suggested and discussed.