Chemical Emulation of Radiation Pinning Center Geometries in High Temperature Superconductors

摘要

Discovery of sub-micron size deposits of (U, Zr, Nd, Ba, 0) in Nd123 enabled application of the U/n method to Nd123, resulting in world record J(sub c). Discovery of an entire class of 200-400 nm size, double perovskite pinning centers, (A,B)REBa(sub 2)O(sub 6), led to (carot)20 new chemical 'point' pinning centers, and enabled replacement of successful but expensive and radioactive (U(sub 0.6)Pt(sub 0.4))REBa(sub 2)O(sub 6) pinning centers with inexpensive, non-radioactive (W(sub 0.5),Zr(sub 0.5))(EBa(sub 2)O(sub 6)). Additional studies proved that the parent compound used for additives strongly effect the critical parameter of pinning center size. Theoretical studies of the cause of decreasing J(sub c), when large ion fluences are used to induce pinning, led to postulating a new class of pinning centers based on multiple-in-line-damage (MILD). Achievement of self-assembling chemical columnar structures in YBCO proved the feasibility of our ultimate goal of producing such chemical pinning centers in small enough diameter to play the role of ideal pinning centers.