| About this Abstract |
| Meeting |
Materials Science & Technology 2019
|
| Symposium
|
Materials vs Minerals: Bridging the Gap between Materials Science and Earth and Planetary Science
|
| Presentation Title |
Thermodynamics of (111) Twin Complexions in Spinel: A First-principles Study |
| Author(s) |
Venkateswara Manga, Thomas Zega |
| On-Site Speaker (Planned) |
Venkateswara Manga |
| Abstract Scope |
The mineral phases such as MgAl2O4-spinel and CaTiO3-perovskites occurring within primitive meteorites exhibit planar faults such as twins, which offer unique evidence of thermal and deformational histories. The local atomic-disorder, strain and chemistry which are otherwise referred to as complexions associated with these twins can reveal the temperature and pressures under which they formed. To this end, employing density functional theory, we have undertaken a thermodynamic analysis of twin complexions in spinels. In contrast to the bulk spinel, (111) twins favor complete inversion within the mixed-cation layer in their vicinity over the entire temperature range. Further, the (111) twins exhibit favorable thermodynamic driving force for V-segregation leading to V-complexions. In this talk we present the implications of these identified twin complexions to the nebular origins of these faults. |