Time-Resolved Synchrotron X-ray Diffraction on Pulse Laser Heated Iron in Diamond Anvil Cell

Abstract

We present time-resolved synchrotron x-ray diffraction to probe the ε-δ phase transition of iron during pulse-laser heating in a diamond anvil cell. The system utilizes a monochromatic synchrotron x-ray beam, a two-dimensional pixel array x-ray detector and a dual beam, double side laser-heating system. Multiple frames of the diffraction images are obtained in real-time every 22 ms over 500 ms of the entire pulse heating period. The results show the structural evolution of iron phases at 17 GPa, resulting in thermal expansion coefficient 1/V(ΔV/ΔT)p = 7.1×10−6 /K for ε-Fe and 2.4×10−5 /K for γ-Fe, as well as the evidence for metastability of γ-Fe at low temperatures below the ε-γ phase boundary.