Speaker
Description
Compositionally complex oxides (CCOs) are promising candidates for thermal barrier coatings (TBCs) due to their low thermal conductivities, which arise from enhanced phonon scattering caused by cation disorder[1]. Compositionally complex rare-earth (RE) zirconate defect-fluorites (RE₂Zr₂O₇) combine low thermal conductivity with high melting temperatures, making them attractive for high-temperature applications. Several RE₂Zr₂O₇ compositions were synthesized via solid-state reaction, and preliminary laboratory X-ray diffraction (XRD) confirmed the formation of single-phase defect-fluorite structures. The room-temperature thermal conductivities of equiatomic compositions were measured using the transient plane source (TPS) method. Notably, (GdDyErYb)₂Zr₂O₇ exhibited an ultralow thermal conductivity of ~0.9 W/m·K. To investigate the influence of processing on cation ordering, compositions (TbYb)₂Zr₂O₇ and (TbHoYb)₂Zr₂O7 were synthesized utilizing two milling methods, traditional ball milling and speed-mixing. To better understand the temperature-dependent structural evolution and persistence of atomic segregation, we conducted high-temperature neutron scattering and pair distribution function (PDF) measurements. Using aerodynamic levitation combined with laser heating, we probed the long- and short-range order at elevated temperatures (1200 – ~3,000 °C) relevant to service conditions. The defect-fluorite structure exhibited phase stability above 2,200 °C and recrystallization when cooled from a partial melt. These insights into high-temperature structural behavior will inform future efforts to design next-generation TBCs optimized for extreme environments in energy production, storage, and conversion systems.
- Yang, Z., et al., Thermal and oxygen transport properties of complex pyrochlore RE2InTaO7 for thermal barrier coating applications. Journal of the European Ceramic Society, 2020. 40(15): p. 6229-6235.
| Topical Area | Emerging research and multimodal techniques |
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