Reprocessing Leading to Lower Thermal Conductivity of ZnO Thermoelectrics
Nanometer sized ZnO powder was co-doped with gamma aluminum oxide and gallium oxide and sintered using a direct current sintering furnace. Sintered samples were reprocessed by crushing the samples in a Carver press, then milling for 4 hours. The reprocessed samples were then re-sintered in the direct current sintering furnace. Heat capacity, density and thermal diffusivity were measured in order to determine thermal conductivity as a function of temperature. Thermoelectric properties were measured. It was found that the thermal conductivity decreased from 7 W/m K to 3.5 W/m K at 805K by using the reprocessing technique. It is projected that the value will be less than 2 W/m K and the figure of merit greater than 0.65 at 1400K.
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D. S. Tucker
EM32, Marshall Space Flight Center, MSFC, Alabama, USA.
School of Nuclear Engineering, Purdue University, West Lafayette, Indiana, USA.
Department of Nuclear Engineering, University of New Mexico, Albuquerque, Mexico.
Department of Metallurgical and Materials Engineering, Tuscaloosa, Alabama, USA.
E-mail: [email protected]