Thermal-Conductivity Of Tl2ba2ca2cu3o10 Ceramics From 300 K Down To 0.1 K

Thermal conductivity, kappa, of two ceramic samples of Tl2Ba2Ca2Cu3O10 has been measured over a temperature range from 300 K down to 0.1 K. At high temperatures, the data show features similar to the thermal conductivity of Y-Ba-Cu-O and Bi-Sr-Ca-Cu-O ceramics in both the magnitude and the temperature dependence. Specifically, a sudden increase in the thermal conductivity is observed at the onset of a superconducting transition near 120 K culminating in a pronounced maximum of kappa around 75 K and an eventual rapid decrease of the thermal conductivity at lower temperatures. From 5 K down to 0.1 K we observe the thermal conductivity to decrease with an average power law exponent between 2.4 and 2.5. Such a temperature dependence is comparable with that for sintered Bi-Sr-Ca-Cu-O samples, but differs from the quadratic variation typical for Bi-Sr-Ca-Cu-O single crystals and the T-linear asymptotic behavior characteristic of Y-Ba-Cu-O and La-Sr-Cu-O ceramics.