Thermal conductivity of Tl2Ba2Ca2Cu3O10 ceramics from 300 K down to 0.1 K

Thermal conductivity, [varkappa], 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 [varkappa] 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.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/29278/1/0000337.pd

Preparation and Characterization of Cu2 S and CuInS2 Films on Various Substrates for Photovoltaic Junctions

[[fileno]]2030170030059[[department]]電機工程學

Characteristics of Y‐Ba‐Cu‐O superconductor films on GaAs with an Al2O3 or AlGaO3 buffer layer

By depositing a buffer layer of Al2O3 on GaAs, we have been able to laser ablate a superconducting film of Y1Ba2Cu3O7−x overtop. The onset of superconductivity is 92 K and zero resistance is observed at 80 K in a structure with a suitably annealed Al2O3 film which is converted to AlGaO3. Both the Al2O3‐GaAs and the Al2O3‐Y1Ba2Cu3O7−x interfaces are remarkably well preserved with virtually no interdiffusion or interaction. The Al2O3 or homolog AlGaO3 film also prevents decomposition of the GaAs at the deposition temperature of 730 °C.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70048/2/APPLAB-58-23-2704-1.pd

Physical and electromagnetic properties of Y‐Ba‐Cu‐O superconductors synthesized with peroxides

The physical and electromagnetic properties of Y‐Ba‐Cu‐O superconductors synthesized with BaO2 (barium peroxide) have been studied. A comparison of reactions with BaCO3 and BaO indicates that the peroxide promotes formation and strong alignment of platelet grains in planes normal to the c axis, yields material with larger grain sizes and aspect ratios, reduces the synthesis reaction time by over half, increases the volume fraction of material that goes superconducting (Meissner effect), and facilitates metallic conduction in the normal state. Critical current densities of 1.1×104 A/cm2 at 77 K have been observed in peroxide‐synthesized material. These beneficial effects may be due to the low melting temperature of BaO2 (450 °C), and the elimination of residual unreacted BaCO3, BaO, and/or C.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70539/2/JAPIAU-67-12-7488-1.pd