Fabrication of Ag-sheathed Bi–Sr–Ca–Cu–O thick films by a novel a.c.-electric field assisted electrophoretic deposition method

Abstract

Ag-sheathed Bi 2Sr 2CaCu 2O δ (BSCCO) tapes with improved microstructural and superconducting properties have been fabricated using a novel electrophoretic deposition technique which involves an application of an alternating current (a.c.) field parallel to the substrate surface in addition to a direct current (d.c.) field during the film deposition. Due to the presence of the additional a.c. field stronger than d.c. field, the angular vibration of BSCCO platy particles along the field direction decreases within the framework of the model of suspended particles. This results in the higher probability of orientation, and hence, deposition of particles with major faces parallel to the a.c. field causing an improvement in the c-axis texturing in green BSCCO films which is key to the fabrication of final BSCCO tapes with predominantly c-axis textured grains. The critical current density ( J c) measured using maximum magnetization data indicates that J c's of a.c. field assisted electrophoretically deposited BSCCO tapes (10 6–10 5 A/cm 2 at 5 K) are 1–2 orders of magnitude higher than that of electrophoretically deposited BSCCO tapes (8×10 4–7×10 2 A/cm 2 at 5 K) without a.c. field.