Strain Engineering in Electrochemical Activity and Stability of BiFeO Perovskites.

Strain engineering is widely employed to manipulate the intrinsic relationship of activity and the crystal structure, while the mechanism and rational strategy toward high-performance devices are still under investigation. Here straining engineering is utilized to manipulate a series of a typical perovskite structures via introducing different types of heteroions (BiMFeO, M = Ca or Y ion). The space group 3 in BiFeO perovskites is found to be maintained with substituting a certain amount of heteroions at Bi sites (<5%), while it would shift into either space groups 4 (with Ca substitute) or (with Y substitute) beyond some critical doping amounts (>5%). Such a transformation is linked with the mismatched crystal strain induced by the heteroions substituted at Bi sites, while the activity, stability, and energy storage capability of BiMFeO have been essentially varied. The results offer a strategy for manipulating stability and activity of perovskites in electrochemical energy conversion and storage.