Composition dependence of electro-optic effect in (111)/(11−1)-oriented epitaxial rhombohedral Pb(Zr x Ti1−x )O₃ thin films prepared by chemical solution deposition

Epitaxial rhombohedral Pb(Zr x Ti 1− x )O 3 (PZT) thin films with different compositions ( x = 0.7–0.55) were fabricated on SrRuO 3 /SrTiO 3 (111) substrates by chemical solution deposition. The domain volume fraction and lattice constants of the thin films varied systematically with the PZT composition. All films exhibited strong ferroelectricity, with remnant polarization values comparable to theoretically estimated values. The effective linear electro-optic (EO) coefficient ( r c ) was not constant with respect to the applied field but varied with the magnitude of AC field due to dynamic domain motion, reaching its maximum value at a certain electric field. The rate of change in r c due to the reversible ferroelastic domain motion, as well as the electric field at which r c peaked, were dependent on the PZT composition. These results indicate that precise control of domain structure and composition is essential to enhance the EO response of thin films.