SPECIFIC-HEAT AND ELECTRON PHOTOEMISSION OF PB-DOPED AND BI-DOPED TL-(BA,SR)-CA-CU-O-(1223) HIGH-TEMPERATURE SUPERCONDUCTORS

Specific heat of Tl0.68Pb0.4Sr1.6Ba0.4Ca2Cu3Oy, Tl0.79Bi0.25Sr1.6Ba0.4 Ca2Cu3Oy and Tl0.74Bi0.3Sr1.8Ba0.2Ca2Cu3Oy has been measured and the e lectronic specific heat coefficient gamma and the specific heal jumps Delta C at T-C have been calculated. The specific heat jumps are about three times smaller than for the YBa2Cu3Ox samples. The core level an d valence band spectra for Tl0.58Pb0.4Sr1.6Ba0.4Ca2Cu3Oy have been det ected at room, at liquid nitrogen and at 125 K temperatures. The Fermi edge has not been observed though pronounced changes of the valence b and shapes have been registered. This is most likely due to the larger anisotropy of electronic band structure of the thallium samples in co mparison to the yttrium superconductors.