Behaviour of the thermal conductivity of high-temperature superconductors around the critical temperature

The electrical resistivity and thermal conductivity of high-Tc superconductors of the Y-Ba-Cu-O and Bi-Sr-Ca-Cu-O systems have been measured in the temperature range of 70 to 120 K. There are differences between the superconducting transition temperature Tc and TA, at which the thermal conductivity changes its dependence on temperature. Wether there exists a connection of structural phase transitions and superconductivity mechanism is still unclear