Giant defect-enhanced electron-phonon interactions in ternary copper oxide superconductors.

A microscopic but schematic model is discussed for defects in compounds such as YBa sub 2 Cu sub 3 O sub (7+delta)O sup square over (2-delta) and La sub (3-x) Ba sub (3+x) Cu sub 6 O sub (14+delta) O sup square above (1-delta) in relation to the superconductive properties of these materials. The discussion shows in detail how T sub c can reach its maximum value at or near the metal-semiconductor transition T sub (ms).