Shock-driven amorphization and melting in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msub> <mml:mi>Fe</mml:mi> <mml:mn>2</mml:mn> </mml:msub> <mml:msub> <mml:mi mathvariant="normal">O</mml:mi> <mml:mn>3</mml:mn> </mml:msub> </mml:mrow> </mml:math>
Céline Crépisson, Alexis Amouretti, M. Harmand, C. Sanloup, P. G. Heighway, Sam Azadi, D. McGonegle, Thomas F. Campbell, Juan Pintor, D. A. Chin, Eric A. Smith, Linda Hansen, Alessandro Forte, Thomas Gawne, Hae Ja Lee, Bob Nagler, Yuanfeng Shi, G. Fiquet, François Guyot, Mikako Makita, A. Benuzzi‐Mounaix, T. Vinci, Kohei Miyanishi, Norimasa Ozaki, T. A. Pikuz, Hirotaka Nakamura, Keiichi Sueda, T. Yabuuchi, Makina Yabashi, J. S. Wark, D. N. Polsin, S. M. Vinko
Abstract
We present measurements on <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"> <a:mrow> <a:msub> <a:mi>Fe</a:mi> <a:mn>2</a:mn> </a:msub> <a:msub> <a:mi mathvariant="normal">O</a:mi> <a:mn>3</a:mn> </a:msub> </a:mrow> </a:math> amorphization and melt under laser-driven shock compression up to 209(10) GPa via time-resolved x-ray diffraction. At 122(3) GPa, a diffuse signal is observed indicating the presence of a noncrystalline phase. Structure factors have been extracted up to 182(6) GPa showing the presence of two well-defined peaks. A rapid change in the intensity ratio of the two peaks is identified between 145(12) and 151(12) GPa, indicative of a phase change. The noncrystalline diffuse scattering is consistent with shock amorphization of <c:math xmlns:c="http://www.w3.org/1998/Math/MathML"> <c:mrow> <c:msub> <c:mi>Fe</c:mi> <c:mn>2</c:mn> </c:msub> <c:msub> <c:mi mathvariant="normal">O</c:mi> <c:mn>3</c:mn> </c:msub> </c:mrow> </c:math> between 122(3) and 145(12) GPa, followed by an amorphous-to-liquid transition above 151(12) GPa. Upon release, a noncrystalline phase is observed alongside crystalline <e:math xmlns:e="http://www.w3.org/1998/Math/MathML"> <e:mrow> <e:mi>α</e:mi> <e:mtext>−</e:mtext> <e:msub> <e:mi>Fe</e:mi> <e:mn>2</e:mn> </e:msub> <e:msub> <e:mi mathvariant="normal">O</e:mi> <e:mn>3</e:mn> </e:msub> </e:mrow> </e:math> . The extracted structure factor and pair distribution function of this release phase resemble those reported for <g:math xmlns:g="http://www.w3.org/1998/Math/MathML"> <g:mrow> <g:msub> <g:mi>Fe</g:mi> <g:mn>2</g:mn> </g:msub> <g:msub> <g:mi mathvariant="normal">O</g:mi> <g:mn>3</g:mn> </g:msub> </g:mrow> </g:math> melt at ambient pressure.