Author ORCID Identifier

https://orcid.org/0009-0004-0189-2669

Semester

Spring

Date of Graduation

2026

Document Type

Thesis

Degree Type

MS

College

Statler College of Engineering and Mineral Resources

Department

Chemical and Biomedical Engineering

Committee Chair

Jianli Hu

Committee Co-Chair

Brandon Robinson

Committee Member

Wenyuan Li

Committee Member

Yuxin Wang

Abstract

This work investigates microwave-assisted calcination as a rapid, energy-efficient alternative to conventional resistive heating for the synthesis of complex oxide powders used in solid oxide electrochemical cells. Ce₀.₉Gd₀.₁O₁.₉₅ (GDC10) and La₀.₆Sr₀.₄Co₀.₂Fe₀.₈O₃–δ (LSCF6428) were synthesized via solid-state and co-precipitation routes to evaluate the influence of precursor chemistry and dielectric behavior on microwave coupling, reaction kinetics, and powder characteristics. Calcination was performed in single-mode and multimode microwave systems using a silicon carbide/alumina susceptor–insulation package to ensure controlled high-temperature processing. A parametric study examining ramp rate, sample size, and temperature revealed that microwave processing reduced calcination time to ~1 hour compared to >21 hours for conventional heating, while also altering microstructural evolution and, in some cases, increasing surface area. Distinct heating regimes were observed, with initial susceptor-driven heating transitioning to intrinsic microwave coupling of LSCF near ~1000 °C, leading to reduced power demand and enhanced volumetric heating. In situ dielectric measurements (450–1000 °C) showed strong temperature-dependent increases in permittivity and loss factor, directly correlating with this transition. Co-precipitated precursors exhibited earlier dielectric activation, improved heating uniformity, and more efficient intrinsic coupling than solid-state counterparts, highlighting the importance of precursor chemistry. Phase evolution and powder properties were characterized using TGA, XRD, and BET. Overall, this work establishes clear relationships between precursor chemistry, dielectric response, and microwave heating behavior, providing mechanistic insight and demonstrating the potential of microwave-driven calcination as a scalable processing route for advanced ceramic materials.

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