The dynamics of ions and the isotope effect in Y Ba2 Cu3 O7-δ

The Bose condensation of pz-hole local pairs at O4 ions in Y Ba2 Cu3 O7-δ is investigated with taking into account the hole interaction with optical oscillations of atoms O 4-Cu l-O 4 quasi-molecules. The hole concentration dependence of superconducting transition temperature Tc and isotope shift factor is shown to be of resonance character. The resonance concentrations are determined by the oscillatory subsystem parameters and the efficiency of electron-phonon interaction. An explanation is put forward for a weak isotope effect in Y Ba2 Cu3 O7-δ and an increase in Tc with frequency of optical oscillations of the O 4 ions observed in some cases