High-quality bismuth telluride crystals having a thickness of only a few atoms were prepared by a method similar to that for graphene mechanical exfoliation. The potential for these materials to be used as thermoelectric materials was then investigated. It was found that the properties of these materials could be fine-tuned by altering the thickness, or the sequence of atomic planes. “Stacked superlattices” were formed using these atomic films, and these ...
Two series of co-doped mifit-layered cobaltites were prepared with compositions of Ca3-xYbxCo4-yAgyO9+delta and Ca3-xEuxCo4-yAgyO9+delta. All of the samples exhibited an increasing thermopower as temperature was increased up to a temperature of 700 K. The sample with the highest power factor and figure of merit was Ca2.95Eu0.05Co3.95Ag0.05O9+delta....
The low-temperature thermoelectric properties of Ca3-xYbxCo4O9+delta systems (x = 0, 0.02, 0.05, and 0.10). It was determined that these systems produced positive thermopower, indicating that the dominant carriers were holes. The electrical resistivity and thermopower were found to increase with increasing Yb3+ content, and the thermal conductivity was found to decrease. The highest calculated thermoelectric figure of merit was 0.037, and this was calculated for the Ca2.95Yb0.05Co4O9+delta sample....
Calcium is partially substituted by bismuth in the Ca3-xBixCoO9+delta (x=0.00, 0.05, 0.10, 0.15, 0.20, and 0.30) system in order to determine how this substitution affects the thermoelectric and magnetic properties of the system. It was determined that the system had a positive thermopower, and thus the main carriers were holes. A maximum thermoelectric figure of merit of 0.091 was achieved with the Ca2.7Bi0.3CoO9+delta sample. The magnetic property test results indicated that ...
Calcium is partially substituted by bismuth in the Ca1-xBixMnO3-delta (x=0.00, 0.02, and 0.05) system in order to determine how this substitution affects the electrical resistivity, thermopower, and thermal conductivity. The experimental results were then used to calculate the thermoelectric figure of merit for each sample. The highest observed figure of merit was 0.047, which represented a 487% increase over the unsubstituted sample....
