Understanding strain-induced martensitic phase transitions in complex crystal structures at high pressures

• Applicant: Professor Dr. Björn Winkler
• Subject Area: Mineralogy, Petrology and Geochemistry
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 563168543

The objective of this project is to employ a recently developed approach to understand strain-induced martensitic phase transitions at high pressures. This approach is based on a combination of a geometric analysis to obtain the transition path in conjunction with density functional theory based calculations to compute structures and enthalpies. This approach has been applied by us to successfully understand the subsolidus transition of quartz to coesite in shocked samples. Here, we propose to quantitatively understand the formation of akimotoite, MgSiO3, by a stress/pressure-induced reaction from enstatite. This will provide insight into the lowering of the transition pressure by stress. It will also allow us to understand the atomistic structure of the interfaces in enstatite-akimotoite intergrowths and the interface energies. We also propose to use this approach to systematically understand stress/pressure-induced reactions in sesquioxides, M2O3. Some sesquioxides are already known to undergo a martensitic phase transition, and here we will systematically investigate, which sesquioxides will transform upon application of stress at high pressures. We will provide the first atomistic model explaining the variant selection mechanism in sesquioxides due to uniaxial pressure.

• DFG Programme: Research Grants