Cheng Sun¹, D. Sprouster², S. Gill², M. Topsakal², L. Ecker², J. Gan¹; ¹Idaho National Laboratory, ²Brookhaven National Laboratory

Self-organization of gas bubbles can cause the formation of gas bubble superlattice in materials under ion irradiation. Here we report the formation of noble gas (He, Ne, Ar and Kr) bubble superlattice in bcc metals (Mo, Fe, W) under ion irradiation. Transmission electron microscopy (TEM) and synchrotron-based small angle X-ray scattering (SAXS) are used to characterize the evolution of gas bubble lattice constant and bubble size, and X-ray Absorption Near Edge Structure (XANES) is used to measure the pressure of ordered Kr bubbles. The stability of gas bubble superlattice under irradiation and thermal annealing is also discussed. Our study advances the understanding on formation mechanism of gas bubble superlattice and provides new insights on the design of stable defect superlattice in harsh environments.