R5: Extraterrestrial materials

[R5-01] Shock deformation microstructures in rutile

*Yuhei Umeda¹, Yuma Nagai¹, Naotaka Tomioka², Toshimori Sekine³, Masashi Miyakawa⁴, Takamichi Kobayashi⁴, Hitoshi Yusa⁴, Takuo Okuchi¹ (1. Kyoto Univ. KURNS., 2. JAMSTEC, 3. HPSTAR, 4. NIMS)

Keywords:Rutile, Shock recovery experiment, Deformation, Defect

Shock response of minerals is an essential clue for understanding of deformation properties of rocks during natural impact events in the history of Earth and planets. Shock-compression experiments are the primary method for simulating such deformation process. Shock recovery experiments using a single-stage propellant were conducted for single crystal and powdered rutile to investigate the effect of heating related to porosity on the shock-induced deformation microstructures. X-ray diffraction (XRD) and transmission electron microscopy (TEM) analyses of the shocked single crystal rutile revealed that a high-density of stacking fault occurred on the (101) plane. The defect suggests that the dominant slip system in the plastic deformation of the crystal is {101}<01>. A part of the crystal is intergrown with the α-PbO₂ structure in a topotaxial relationship: [010]_Rt // [001]_α-PbO2. Based on topological analysis, the single crystal rutile would have transformed to the α-PbO₂ structure via the calcium-fluoride structure concomitantly with shear deformation. Meanwhile, the shocked powdered rutile consists mainly of particles with pervasive entangled dislocations and recrystallized particles, where the α-PbO₂ structure did not occur at all. Considering the absence of stacking faults, a possible dominant slip system in the shocked powdered rutile is {110}[001].