Dependence of superconducting temperature on chemical bond parameters in YBa 2Cu 3O 6 + δ ( δ = 0 − 1)

Abstract

The chemical bond parameters, that is ionicities and average energy gaps, for all types of chemical bonds in YBa 2Cu 3O 6 + δ have been investigated with variation of oxygen content δ ( δ = 0.0, 0.35, 0.45, 0.58, 0.64, 0.73, 0.78, 0.81, 0.95, 1.00). The theory used is the complex crystal chemical bond theory, which is the development of P-V-L theory. The two plateaus near 90 K and 60 K in superconducting transition temperatures, and the disappearance of superconductivity with the change of oxygen content, were reasonably explained by chemical bond parameters. The results also showed that the CuO chains play a vital role in the transition from non-superconductors to superconductors, and the highest transition temperature occurred when the plane-chain reached a coupling state.