Enhancement of spontaneous polarization in lead zirconate titanate thin films by Dy3+ substitution

Spontaneous polarization can be enhanced by increasing the crystal anisotropy of tetragonal Pb(Zr,Ti)O3 [PZT] lattice by Zr and Ti-site substitution with Dy3+ cations. Spontaneous polarization (Ps) in epitaxial film of 2% Dy3+-substituted tetragonal Pb(Zr0.40Ti0.60)O3 [Dy–PZT] was compared with that of nonsubstituted Pb(Zr0.40Ti0.60)O3 [PZT] to investigate intrinsic contribution of the Dy3+ substituion to the Ps improvement. Epitaxial thin films of PZT and Dy–PZT with (111) orientations were grown on (111)cSrRuO3//(111)Pt//(100)YSZ//(100)Si substrates by chemical solution deposition. The saturated polarization values of PZT and Dy-PZT films with (111) orientation were 41 and 48 µC/cm2, respectively. The estimated Ps values of PZT and Dy–PZT films from the saturation polarization values were 71 and 84 µC/cm2, respectively. The Ps value of this PZT was in good agreement with previous reports. The increase in Ps of the epitaxial Dy3+-substituted PZT film is attributed to the enhancement of the crystal anisotropy, i.e., tetragonality, of the tetragonal PZT lattice. This shows that the enhancement of the ferroelectricity of the tetragonal PZT films can be achieved by ion substitution, just as it can in Bi4Ti3O12-based film.
journal article