Femtosecond laser synthesis of the high-pressure phase of iron

The synthesis of the high-pressure epsilon phase of iron, which has not been observed under a conventional shock compression, was attained using a femtosecond laser. The lower pressure and temperature alpha phase (bcc) transforms to the gamma phase (fcc) at higher temperatures and to the epsilon phase (hcp) at higher pressures. A shock induced alpha to epsilon phase transition in iron is one of the most famous transitions under high pressure. The induced high-pressure epsilon phase by a conventional shock loading returns to the epsilon phase and it is not quenched after the shock release because this transition is considered to be diffusionless. Crystalline structures in a recovered iron sample after the ferntosecond laser (800 nm, 120 fs, 10(14) W/cm(2)) irradiation were determined using the electron diffraction and the synchrotron X-ray diffraction methods. These results show the existence of the epsilon phase and the fee structure in the recovered iron. The femtosecond laser-driven shock wave may have the potential to synthesis high-pressure phases of other materials that has not been done using the conventional shock wave.