| Abstract: | In this paper, based on the phonon-exciton mechanism, the superconductivity of yttrium barium copper oxide (YBCO) system is explained. The transition temperature (Tc) 's formula is derived by the extended BCS-Eliashberg theory, i.e. phonon-exciton mechanism and McMillan's energy gap function, and the Tc's expressions isreduced by using the Einstein spectrum. Last, the calculating method of element metal effective phonon spectrum is used to the high Tc cuprate YBCO system by using a crystal average atom approximation model. The theoretical analysis and calculational results show that the superconductivity of high Tc YBCO system maybe described by phonon-exciton model. |
