Design & Manufacturing of High Performance Thermoelectric Oxide Ceramics for Clean Energy Conversion

Author

• Geoffroy GauneauFollow

Semester

Spring

Date of Graduation

2026

Document Type

Dissertation

Degree Type

PhD

College

Statler College of Engineering and Mineral Resources

Department

Mechanical and Aerospace Engineering

Committee Chair

Xueyan Song

Committee Member

Yun Chen

Committee Member

Cesar-Octavio Romo-De-La-Cruz

Committee Member

Zhichao Liu

Committee Member

Jacky Prucz

Abstract

As global energy demand grows, over sixty percent of primary energy is lost as waste heat—a significant source of recoverable energy. Thermoelectric (TE) technology offers a direct pathway to recovering this energy by converting temperature gradients into electricity, with efficiency governed by the dimensionless figure-of-merit zT = S²ρ⁻¹k⁻¹T. Despite their promise, oxide-based thermoelectrics remain constrained by modest performance in polycrystalline form and limited manufacturing scalability. This dissertation addresses both challenges through a coherent research program spanning materials design, dopant engineering, and additive manufacturing. The first body of work focuses on Ca₃Co₄O_9+δ (CCO), where a progressive doping strategy was developed to advance the understanding of grain boundary engineering through oversized dopants. By systematically comparing stoichiometric and non-stoichiometric rare-earth addition, this work established that addition mode critically governs transport property decoupling. Building on this, the dual addition of a rare-earth ion and an oversized dopant — where the rare-earth ion tunes carrier concentration and the oversized dopant drives preferential grain alignment through boundary segregation — achieved a peak zT of 0.57 at 1023 K, a 55% improvement over the pristine material. The second body of work turns to DyCoO₃ (DCO), a largely unexplored oxide with an exceptionally high Seebeck coefficient. Through the first systematic processing-parameter study of this material, combined with calcium Dy-site substitution to tune carrier density, a peak zT of 0.192 at 573 K was achieved — establishing DCO as a viable candidate for mid-temperature waste heat recovery. The third and most distinctive contribution of this work is the translation of these chemistry-optimized ceramics into functional thermoelectric devices via Direct Ink Writing (DIW). By developing high-solids-load oxide slurries and printing complex leg geometries capable of surviving full thermal processing cycles, this work demonstrated a nearly three-order-of-magnitude increase in power density — from 2.04 μW/cm² to 2.03 mW/cm² — validating DIW as a scalable, low-cost path from optimized oxide powders to real-world thermoelectric generators.

Recommended Citation

Gauneau, Geoffroy, "Design & Manufacturing of High Performance Thermoelectric Oxide Ceramics for Clean Energy Conversion" (2026). Graduate Theses, Dissertations, and Problem Reports. 13296.
https://researchrepository.wvu.edu/etd/13296