Semester

Fall

Date of Graduation

2020

Document Type

Thesis

Degree Type

MS

College

Statler College of Engineering and Mineral Resources

Department

Mechanical and Aerospace Engineering

Committee Chair

Xueyan Song

Committee Co-Chair

Yun Chen

Committee Member

Ever Barbero

Abstract

Thermoelectric generators produce electricity by directly converting temperature differences into electrical energy through Seebeck effect. Thermoelectric generators possess many unique features, such as having no moving part and being very reliable with a relatively long lifespan once built. They are solid-state waste heat harvesters. With various waste heat available throughout many industries, thermoelectric generators could offer economically competitive renewable energy. The current state of the art thermoelectric materials includes materials with relatively toxic elements and must work under vacuum, making them quite expensive to produce. Among the various thermoelectric materials, ceramic oxides have been proved to be more chemically stable at high temperatures. Nevertheless, the thermoelectric ceramic oxides do not yet reach the efficiency of the current state of the art materials. Recent efforts have been made to improve the efficiency of ceramic oxide for their potential commercial applications in the waste heat harvester. The present work encompasses the synthesis, characterization, and analysis of p-type thermoelectric Ca3-xCo4O9+δ doped with rare earth elements. The sol-gel chemical solution was applied to synthesize the precursor materials for ceramic oxide with homogeneous chemistry. The results show that to a certain substitution level, doping rare-earth element decreases the thermal conductivity and improves the thermoelectric properties of the oxide thermoelectric materials. Meanwhile, doping also introduces the formation of nano-inclusions that is highly desirable for thermoelectric materials. The formation mechanism of the nano-inclusions and their resultant impact on the electrical and thermal properties of the misfit layered oxide is systematically investigated through this thesis work.

Embargo Reason

Patent Pending

Available for download on Saturday, December 04, 2021

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