Phase transition and superconductivity high-T-c oxides

On the basis of new experimental studies of specific heat, magnetic properties and thermal expansion it was shown that dielectric-metal phase transitions were the consequence of delocalization of the heavy holes located on metal-apical oxygen bonds in the high-T-c oxide systems. The ordered arrays of such holes (CDW) results in the dielectric gaps in electron spectrum and anomalous negative thermal expansion. The free carriers introduced by doping can couple through excitations of these localized holes (local bosom). The high-T-c superconductivity will possess anomalous H-c2(T) dependence and lambda-type specific heat jump at T-c. This local bosons model is the basis for explanation of the obtained experimental data.