Crystallographic preferred orientation in wüstite (FeO) through the cubic-to-rhombohedral phase transition

• Published in: Physics and chemistry of minerals Vol. 39; no. 8; pp. 613 - 626
• Main Authors: Kaercher, P., Speziale, S., Miyagi, L., Kanitpanyacharoen, W., Wenk, H.-R.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer-Verlag 01.09.2012; Springer Nature B.V
• Subjects: Alignment; Ambient temperature; Crystallography; Crystallography and Scattering Methods; Deformation; Diamond anvil cells; Diffraction patterns; Earth and Environmental Science; Earth Sciences; Geochemistry; Light diffraction; Light sources; Mineral Resources; Mineralogy; Original Paper; Phase transitions; Planes; Polycrystals; Preferred orientation; Slip; Texture; Wustite; X-ray diffraction; Diamond anvil cell; Wüstite; Preferred orientation; Phase transition
• ISSN: 0342-1791; 1432-2021
• DOI: 10.1007/s00269-012-0516-x

Magnesiowüstite, (Mg 0.08 Fe 0.88 )O, and wüstite, Fe 0.94 O, were compressed to ~36 GPa at ambient temperature in the diamond anvil cell (DAC) at the Advanced Light Source. X-ray diffraction patterns were taken in situ in radial geometry in order to study the evolution of crystallographic preferred orientation through the cubic-to-rhombohedral phase transition. Under uniaxial stress in the DAC, {100} c planes aligned perpendicular to the compression direction. The {100} c in cubic became { } r in rhombohedral and remained aligned perpendicular to the compression direction. However, the {101} c and {111} c planes in the cubic phase split into { } r and { } r , and (0001) r and { } r , respectively, in the rhombohedral phase. The { } r planes preferentially aligned perpendicular to the compression direction while { } r oriented at a low angle to the compression direction. Similarly, { } r showed a slight preference to align more closely perpendicular to the compression direction than (0001) r . This variant selection may occur because the 〈 〉 r and [0001] r directions are the softer of the two sets of directions. The rhombohedral texture distortion may also be due to subsequent deformation. Indeed, polycrystal plasticity simulations indicate that for preferred { }〈 〉 r and { }〈 〉 r slip and slightly less active { }〈 〉 r slip, the observed texture pattern can be obtained.