a1 Department of Materials Science and Engineering, University of Maryland, College Park, Maryland 20742; and Institute for Chemical Research, Kyoto University, Kyoto 611-0011, Japan
a2 Department of Materials Science and Engineering, University of Maryland, College Park, Maryland 20742
a3 Department of Physics and Astronomy, Rowan University, Glassboro, New Jersey 08028
a4 Department of Materials Science and Engineering, University of Maryland, College Park, Maryland 20742
We review our work on combinatorial search and investigation of morphotropic phase boundaries (MPBs) in chemically substituted BiFeO3 (BFO). Utilizing the thin-film composition spread technique, we discovered that rare-earth (RE = Sm, Gd, and Dy) substitution into the A-site of the BFO lattice results in a structural phase transition from the rhombohedral to the orthorhombic phase. At the structural boundary, both the piezoelectric coefficient and the dielectric constant are substantially enhanced. It is also found that the observed MPB behavior can be universally described by the average A-site ionic radius as a critical parameter, indicating that chemical pressure effect due to substitution is the primary cause for the MPB behavior in RE-substituted BFO. Our combinatorial investigations were further extended to the A- and B-site cosubstituted BFO in the pseudoternary composition spread of (Bi1−x Sm x )(Fe1−y Sc y )O3. Clustering analysis of structural and ferroelectric property data of the fabricated pseudoternary composition spread reveals close correlations between the structural and ferroelectric properties. We show that the evolution in structural and ferroelectric properties is controlled solely by the A-site Sm substitution and not the B-site Sc substitution.
(Received July 23 2012)
(Accepted August 30 2012)
This paper has been selected as an Invited Feature Paper.