Invited Speaker
Assoc. Prof. Fangwei Guo
Shanghai Jiao Tong University
E-mail: fwguo2014@sjtu.edu.cn
Title: Synthesis pathways of (HfZrTiCe/La/Y)O2-x nanoparticles via benzyl alcohol route at critical temperature
Profile:
Dr. Fangwei Guo, associate professor at the Key Laboratory of Advanced High-Temperature Materials and Precision Forming at Shanghai Jiao Tong University, was a returned scholar from the UK and Switzerland. She has long been engaged in fundamental and applied research on lightweight ceramic thermal protection materials for aerospace. Her efforts have led to the development of some novel ceramic coating materials that have been successfully applied in practical settings. She has completed over 20 national and municipal projects as principal investigator. She has published more than 100 research papers in journals such as J Am Ceram Soc., J Euro Ceram Soc., J Adv Ceram., Carbon, and Corrosion Science. Additionally, she has filed over 70 national invention patents, with more than 41already granted. She developed the ZrSi precursor ceramic coating materials and technology, whic have been applied to the thermal protection of 14 Long March series carrier rockets since 2022. Her academic achievements have won the "Gold Award" at the 28th National Invention Exhibition, the 2024 National Invention and Entrepreneurship Project Award, the "Gold Award" of the 36th Shanghai Excellent Invention (ranked 1st), the 2024 Shanghai Science and Technology Award, and the 2024 Shanghai Industry-University-Research Cooperation Excellent Project Award. He has been selected into the high-level talent plans of Shanghai and Zhejiang Province.
Abstract:
High entropy oxides (RE-HEO) containing rare earth elements can provide excellent phase stability and oxidation resistance. However, the controllable synthesis of RE-HEO at low temperature is a challenge due to poor understanding on nucleation. We synthesized the (HfZrTiLn)-HEO nanoparticles with 15% ionic radius mismatch via benzyl alcohol route at 220 °C -5 min in presence of PtCl4 and Fe(acac)3. Nucleation pathways of the 5HEO at the critical temperature were elucidated by using a comparison study of conventional heating and microwave irradiation heating. Consistency of XRD patterns and STEM-EDX observation indicate that the resultant Hf-OBn monomers acted as the nucleation center of the 5HEO, determined by diffusion kinetics. The nucleation rate depended on the metal monomers assembly and esterification reaction, which was accelerated by water vapor pressure produced in-situ by PtCl4 catalyst. The Fe-metal organic cages served as the structure stabilizer of Zr/Ti monomers, and prevented early hydrothermal reaction route.