Irradiation induced metastable phase formation in thermally immiscible Co-Ag multilayers

摘要

The micro structural evolution of Ar~+ ion irradiated Co/Ag multilayers with the fluence range of 1 x 10~(16)-7 x 10~(16) ions/cm~2 is studied by transmission electron microscopy. The electron diffraction pattern of as-prepared sample shows the sharp lines from both Co and Ag. Ag nanoparticles were observed after irradiation to a fluence of 1 x 10~(16) ions/cm~2. Upon irradiation to a fluence of 7 x 10~(16) ions/cm~2, a new metastable phase, Ag_3Co, with hcp structure (DO_(19)) and having nanosized grains, is observed. The formation of irradiation induced metastable phase in Co/Ag multilayer system is discussed based on total energy calculations and kinetic considerations.