Physical properties in polydomain c/a/c/a phase PbTiO3 ferroelectric thick films: effect of thermal stresses

The thermal stress dependence of the physical properties of polydomain PbTiO3 films on different substrates are investigated using a nonlinear Ginzburg–Landau–Devonshire thermodynamic model as a function of deposition temperature T G and thermal expansion coefficients. It is found that the thermal strain has a large impact on the ferroelectric polarization states and other physical properties for the thicker ferroelectric thin films. Extrinsic contributions from 90° domain wall displacements are found to dramatically impact the dielectric, pyroelectric, and piezoelectric responses. Most importantly, the dielectric and piezoelectric constants in the polydomain c/a/c/a phase is much larger than that of the monodomain c phase, while the results are opposite for the ferroelectric polarization and pyroelectric coefficient. Careful choice of thermal stress and domain states allows one to harness the intrinsic and extrinsic contributions to obtain large physical responses. Our work is in good agreement with experimental results and phase–field simulation.