Stoichiometric relations in high-temperature superconducting compounds

Abstract

Applying the Jing and Gonser model for the high-T _c superconductivity based on electron hopping the Stoichiometric connections and appropriate restrictions are given. It is shown that for the compounds of typeA _2−x B _xCuO₄ andAB ₂Cu₃O_9−x, whereA is a trivalent rare-earth ion andB is a divalent alkali earth ion, the superconductivity is realized only if 0<x<0.5 or 1.75<x<2.5, respectively, and the strongest effects should be observed when x=0.25 or x=2.125. Some other generalized forms of high-T _c superconducting compounds are propounded and considered, too. The optimum compound which contains fluorine atoms should be of the form YBa₂Cu₃F₂O_5.875. All the relations presented find confirmation in experiments.