Cohesive properties of PbBi/Fe3O4 and PbBi/(Fe,Cr)3O4 interfaces

Abstract

First principles calculations reveal that the effects of PbBi on the cohesive properties of Fe₃O₄ and (Fe,Cr)₃O₄: PbBi can reduce the cohesive strength of the oxides, and the contents of O and Cr on the O-terminated oxide side play a significant role in the cohesive properties of the PbBi/Fe₃O₄ and PbBi/(Fe,Cr)₃O₄ interfaces. Specifically, the performance of oxidation decreases more significantly under the conditions of insufficient oxygen, and a high ratio of Cr of the subsurface of oxides can lead to the reduction of the cohesive properties of O-terminated interfaces. Calculations also show that the Pb–O-terminated interfaces are energetically favorable and are more stable than the Bi–O-terminated surfaces due to the strong bond of Pb–O, while the Bi–Cr and Bi–Fe interfaces are more stable than the Pb–Cr and Pb–Fe interfaces. Moreover, it is found that the stability and cohesion of the PbBi/Fe₃O₄ and PbBi/(Fe,Cr)₃O₄ interfaces will decrease when the oxygen concentration is insufficient or the degree of wetting of PbBi of oxides is low, and the PbBi/Fe₃O₄ interface is more sensitive to these conditions. The bond-dissociation energies and electronic structures provide a deep understanding of various interface properties, and the obtained results are in good agreement with experimental measurements in the literature.