Abstract
The YBa2Cu3-x(doped element)xO7-δsamples were prepared by solid-state reactions and studied by means of XRD, positron annihilation technique and simulation calculation. The results show the local electron density nesaturation and variations of oxygen content, which can be explained by the cluster effect. Another important new result is that the superconductivity does not depend directly on the valence electron density with different dopant. The Tcseems to lose the association with the nevariation. The dopants can be regarded as a kind of defects is similarly an adding or a losing oxygen ion. Oxygen interstitials reflect fractal distributions of dopants. The oxygen content and distribution reflect the superconductivity of the samples.
Publisher
Trans Tech Publications, Ltd.