Ferroelectric properties of BaZrO3/PbZrO3 and SrZrO3/PbZrO3 superlattices: An ab-initio study

Ferroelectric properties of tetragonal (BaZrO3)(1)/(PbZrO3)(n) and (SrZrO3)(1)/(PbZrO3)(n) superlattices are studied as the ratio of PbZrO3 was changed (n = 1-3) in the superlattices using density functional theory (DFT) method as well as an electrostatic model. We show that PbZrO3-an antiferroelectric in bulk displays ferroelectric behavior in the superlattices combined with the paraelectric cubic (BaZrO3) or (SrZrO3). The electrostatic model and the DFT calculations show that the polarization and the tetragonality (c/a ratio) are reduced in the BaZrO3/PbZrO3 and SrZrO3/PbZrO3 superlattices with respect to the bulk tetragonal PbZrO3. Moreover, the polarization and the tetragonality of superlattices increase with increasing the fraction of PbZrO3 in superlattices. The estimated polarization of the (BaZrO3)(1)/(PbZrO3)(1) superlattice is (36.21 mu C/cm(2)), while it is (56.82 mu C/cm(2)) for the (BaZrO3)(1)/(PbZrO3)(3) superlattice. The estimated polarization of the (SrZrO3)(1)/(PbZrO3)(1) superlattice is (55.28 mu C/cm(2)), while it is (64.86 mu C/cm(2)) for the (SrZrO3)(1)/(PbZrO3)(3) superlattice. These ferroelectric superlattices have good lattice matching with many Heusler alloys and they could be very useful as ferroelectric substrates to these systems. (C) 2014 AIP Publishing LLC.