Due to the ever-increasing energy demand and growing global concern over the environmental impact of carbon dioxide emissions, there is an urging need to seek solutions to transit from fossil fuels to sustainable energy. Only 30% of the energy used every day is converted into useful work and the remaining 70% is wasted as dissipated heat during energy conversion, transportation and storage. This giant loss is itself a source of recyclable energy that can be renewed into useful energy. Thermoelectric (TE) materials show great promise for converting waste heat energy into electricity. TE systems have many unique advantages such as silent operation, time reliability, and dimensional scalability. Most recently, researchers have found that MnO2 nanoparticles show a giant Seebeck coefficient of S = 20 mV/K, which is 100 times higher than bismuth telluride, one of the best TE materials. These researchers concluded the paper claiming that the giant S is related to the surface density of the electronic states (DOS). However, no figure of merit measurements (ZT) have been reported so far. In this project, we present preliminary results of ZT, Seebeck coefficient and thermal and electrical conductivities as a function of particle electrical resistance in the range of 10-80 O for particle sizes in the range of 5 nm-150 µm. ZT values ranged between 0.12-0.18. The samples with the smallest particle size show the greatest promise for further increasing the ZT.

Additional Abstract Information

Student(s): Nicholas J. Francis, Morgan E. Hedden

Department: Physics and Astronomy

Faculty Advisor: Dr. Costel Constantin

Type: Poster

Year: 2014

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