Levitation And Suspension Forces Measurement System For High Tc Superconductors

The interaction forces, attraction (suspension) and repulsion (levitation) between a permanent magnet and different bulk Yttrium-based superconductors were carried out with an automatic system developed in our group, which is reproducible, reliable and low cost. Two superconducting samples of YBa2Cu3O7-delta (YBCO) prepared by solid-state reaction method (S) and by the melt-textured growth method (MTG) were used. Both samples were characterized by XRD technique and presented the characteristic peaks and intensity relations of the YBCO-123 superconducting phase. Oxygen deficiencies delta > 0,15 and delta < 0,10 for the S and MTG samples respectively, were observed. Both samples displayed different hysteresis behavior in the Force (F) vs. Distance (z) measurements when they were field cooled (FC) and zero field cooled (ZFC). This behavior agrees with hysteresis loops observed in magnetization measurements. Both levitation and suspension phenomena were observed in the MTG sample with large hysteresis loops of the force. On the contrary, the S sample with small hysteresis loops did not show a suspension force, only displayed a slight levitation force.