Y1-2X CAX THX BA2 CU3 O7-

Thermoelectric power and evidence of carriers localization in Y1_2xCaxThxBa2Cu307_s superconductors

In this study polycrystaline samples of Y1_2xCax ThxBa2Cu3O7_s with x=0, 0.025, 0.05, 0.075 were made by standard solid state methods. The transport and superconducting properties have been studied by the thermoelectric power S(x,T) measurements as a function of temperature and doping concentration. The critical temperature decreased linearly by increasing the doping concentration. S(x,T) was analysed and well described by a phenomenalogical narrow band model. The critical temperature, room temperature thermoelectric power S(290 K) and phenomenological narrow band model results were suggested in wich charge carrier (hole) localization was the main reason of the suppression of superconductivity in this alloys.