Study of the flux pinning in the YBa₂Cu₃O_y system

We have carried out a systematic study of the YBa2Cu3Oy(YBCO) single crystals including those grown from (YBCO)/Ag2O composite. The resistive transition, and the detailed I-V characteristic in magnetic fields behaves differently for crystals grown by different methods. The results suggest that the flux dynamics in this high Tc oxide is complex and depends strongly on the sample conditions. Detailed electrical and magnetic properties in conjunction with the microstructure will be presented and discussed in comparison with the existing theories. © 1991.