Subnanosecond phase transition dynamics in laser-shocked iron

Hwang, H.; Galtier, E.; Cynn, H.; Eom, I.; Chun, S. H.; Bang, Y.; Hwang, G. C.; Choi, J.; Kim, T.; Kong, M.; Kwon, S.; Kang, K.; Lee, H. J.; Park, C.; Lee, J. I.; Lee, Yongmoon; Yang, W.; Shim, S. -H.; Vogt, T.; Kim, Sangsoo; Park, J.; Kim, Sunam; Nam, D.; Lee, J. H.; Hyun, H.; Kim, M.; Koo, T. -Y.; Kao, C. -C.; Sekine, T.; Lee, Yongjae

doi:10.1126/sciadv.aaz5132

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Subnanosecond phase transition dynamics in laser-shocked iron

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Abstract

Iron is one of the most studied chemical elements due to its sociotechnological and planetary importance; hence, understanding its structural transition dynamics is of vital interest. By combining a short pulse optical laser and an ultrashort free electron laser pulse, we have observed the subnanosecond structural dynamics of iron from high-quality x-ray diffraction data measured at 50-ps intervals up to 2500 ps. We unequivocally identify a three-wave structure during the initial compression and a two-wave structure during the decaying shock, involving all of the known structural types of iron (α-, γ-, and ε-phase). In the final stage, negative lattice pressures are generated by the propagation of rarefaction waves, leading to the formation of expanded phases and the recovery of γ-phase. Our observations demonstrate the unique capability of measuring the atomistic evolution during the entire lattice compression and release processes at unprecedented time and strain rate.

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Hwang, H., Galtier, E., Cynn, H., Eom, I., Chun, S. H., Bang, Y., Hwang, G. C., Choi, J., Kim, T., Kong, M., Kwon, S., Kang, K., Lee, H. J., Park, C., Lee, J. I., Lee, Yongmoon, Yang, W., Shim, S. -H., Vogt, T., Kim, Sangsoo, Park, J., Kim, Sunam, Nam, D., Lee, J. H., Hyun, H., Kim, M., Koo, T. -Y., Kao, C. -C., Sekine, T., Lee, Yongjae. 2020-06-05. Subnanosecond phase transition dynamics in laser-shocked iron. https://doi.org/10.1126/sciadv.aaz5132

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