Metastable Phase Formation in the Immiscible Ru–Pd System Studied byAb InitioCalculation and Ion Mixing

Abstract

In the equilibrium immiscible Ru-Pd system, the total energies for five possible structures, i.e., A15, D0 9 , D0 19 , L1 2 , and L6 0 , with a stoichiometry of RuPd 3 were calculated as a function of lattice constants, based on the Vienna Ab Initio Simulation Package (VASP). The calculation results predicted that the D0 19 , L1 2 , and L6 0 structures were relatively stable and had similar energies, if the spin polarization effect of the Ru atoms was considered, and that the L1 2 structure was the most stable one, if the spin polarization effect was considered to be depressed by the crystal field. Interestingly, in ion mixing experiments, a metastable crystalline Ru-Pd phase of fcc structure was indeed obtained in the Ru-Pd multilayered films with an overall composition of Ru 20 Pd 80 and its lattice constant determined by diffraction analysis also confirmed the relevance of the ab initio calculations.