Influence of Zr doping on the structure and ferroelectric properties of BiFeO3 thin films

We have prepared thin films of BiFe1-xZrxO3 (x=0.0-0.15) by chemical solution deposition on Pt/Si substrates. Structural characterization of the films using x-ray diffraction and Raman spectroscopy suggests lattice distortion upon doping for x<0.15. This also appears to be the limit for pure phase formation. Ferroelectric measurements reveal that Zr doping leads to reduction in the remnant polarization and an increase in the coercive field, attributed to lattice distortion. Dielectric measurements indicate that the doped compositions exhibit absence of low frequency relaxation, usually associated with defects and grain boundaries. Absence of Fe2+ in our films was verified using x-ray photoelectron spectroscopy. Role of Zr in controlling the film's properties has been explained in terms of changes in the bond strength.