2014 年 56 巻 1 号 p. 15-21
We are developing an ultra-short pulse powder X-ray diffraction method using X-ray pulses of high brilliance and femtosecond pulse width from the X-ray free-electron laser apparatus in SACLA, Japan. The distinctive feature of this method is detection of anisotropic crystal structure deformation during non-thermal process. We have applied this method to some materials, including chalcogenide Ge-Sb-Te, porous coordination polymers, hydroxyhydrides, etc. In this review, we will introduce some preliminary results of observation of photo-induced anisotropic lattice expansion in a non-thermal process in a metastable face-centered cubic Ge2Sb2Te5 crystal.