Artificial Morphotropic Phase Boundary Associated with Nano-Clustering in Lead Zirconate – Lead Titanate Composite Films

Many ferroelectrics, such as lead zirconate titanate, are widely known to exhibit excellent ferroelectric and piezoelectric properties near the morphotropic phase boundary (MPB), where two phases coexist in a solid solution form. Nano-clustering by aerosol deposition (AD) enables multiphase films to be prepared from distinct phases at room temperature. Herein, nano-clustered (NC) antiferroelectric xPbZrO₃ (PZ) – ferroelectric (1-x)PbTiO₃ (PT) films are fabricated to assess the possibility for artificial MPB (aMPB) behavior. This is done by comparing the composition-dependent ferroelectric and piezoelectric properties with those of solid solution (SS) Pb(Zr_x,Ti_1-x)O₃ (PZT) films. The origin of the aMPB behavior in the NC PZ-PT film is verified through phase field modeling to be the internal local depolarization field generated in AFE. Both the SS PZT film and the NC PZ-PT film exhibited the largest dielectric constants (ɛ_r) of 820 and 650, and large signal piezoelectric constant (d_33,f*) of 86 and 82 pm V⁻¹, respectively, at a near-MPB composition (x = 0.5) compared to those of the Ti-rich (x = 0.1) and Zr-rich (x = 0.9) compositions, indicating aMPB behavior. The aMPB behavior induced by the nano-clustering is expected to be expanded to combinations of various material compositions that do not form solid solutions.