Characterization of planar crystal lattice defects in the high-temperature superconductor YBa2Cu3O7

Transmission electron microscopy shows that sintered YBa2Cu3O7 contains many planar defects in the a-b plane. They range from stacking faults to 10--100 nm thick sheets of disordered material that extend through the entire crystal grains. The stacking faults may be precursors for the thick layers of disordered material. In this letter we characterize the stacking faults and find that the displacement vector switches from (a/2,0,c/6) to (b/2,0,c/6) as the faults cross the twin boundaries