Large Enhancement in Oxygen Mobility in the Superconductors RBa 2 Cu 3 O 7 with Increasing Rare-Earth Size

Abstract
Ultrasonic composite oscillator measurements of the mechanical relaxation in RBa2Cu3O7–8 arising from oxygen hopping in the basal chain layer show enhancements in oxygen mobility of 20, 50, and 100 times for R = gadolinium, neodymium, and lanthanum, respectively, above that for R = yttrium. The use of the larger rare earths offers a practical solution to the major problem of slow oxygen diffusion in single crystals and bulk, dense material for wires and melt-textured monolithic bodies.