Improvement of Thermoelectric Oxides for a Simple Thermoelectric Generator
Date
2015-09
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
New York State College of Ceramics at Alfred University. Kazuo Inamori School of Engineering.
Abstract
Three thermoelectric compositional series, n-type Ga3-xIn5+xSn2O16, p-type
Ca3-xSrxCo4O9, and p-type Ca3-yAgyCo4O9 were synthesized using solid state techniques.
Comparisons of thermoelectric properties for Ga3-xIn5+xSn2O16 using pressureless
sintering in air and spark plasma sintering consolidation were completed. Seebeck
coefficient, electrical conductivity, and thermal conductivity were measured in argon
from 200°C-1000°C. Seebeck coefficient was negative, indicating electron-type
conduction. Overall electrical conductivity increased for SPS condensed samples. Figure
of merit (ZT) of solid state sintered samples ranged from 0.23-0.46, and SPS condensed
samples ranged from 0.08-1.12 at 1000°C. ZT values above 1.0 were observed due to
increasing mobility and thermal conductivity values lower than 3W/m*K.
Comparisons of thermoelectric properties from different sintering temperatures
were completed for Ca3-xSrxCo4O9, and Ca3-yAgyCo4O9. Seebeck coefficient, electrical
conductivity, and thermal conductivity were measured in air from 200°C-800°C. Seebeck
coefficient was positive, indicating hole-type conduction. Electrical conductivity
increased as a function sintering temperature. Thermal conductivity of undoped samples
increased from 0.5W/m*K to 1.5W/m*K at 800°C due to decreasing porosity, but did not
decrease with doping due to secondary phases in the material. Doped compositions had
ZT values ranging from 0.07-0.6, and undoped samples had ZT values ranging from
0.25-0.6 at 800°C. Similar ZT ranges are due to the wide range of electrical and thermal
conductivity values observed.
Two compositions and processing methods were chosen, SPS consolidated
Ga2In6Sn2O16 and Ca3-xSrxCo4O9 sintered at 1100°C, for fabricating a simple oxide
thermoelectric generator. A one leg pair π-module was fabricated and tested at two
different hot side temperatures for ΔT of ~200°C, and ~600°C. Overall, electrical power
generated was >1mW and efficiency was 0.21% when the hot side temperature was set at
800°C and cold side temperature was set at 200°C.
Description
Advisory committee members: Dawei Liu, Scott Misture. Dissertation completed in partial fulfillment of the requirements for the degree of Masters of Science in Ceramic Engineering at the Kazuo Inamori School of Engineering, New York State College of Ceramics at Alfred University
Type
Thesis