Systematic study of structure and piezoelectric properties of Pb(Ni1/3Nb2/3)O3-PbTiO3 by in situ synchrotron diffraction

Lead-based ferroelectric materials are extensively employed in industrial applications and everyday life due to their excellent ferroelectric and piezoelectric performance. Pb(Ni_1/3Nb_2/3)O₃-PbTiO₃ (PNN-PT) is a typical binary relaxor ferroelectric system, whose refined structure and piezoelectric properties have not been systematically investigated. In this study, evolution of electric field-based crystal structure and variation of ferroelectric, piezoelectric, as well as dielectric properties with composition and temperature of (1 ? x)PNN-xPT (0.32 ≤ x ≤ 0.36) ceramics were studied in full detail. The optimal performance is obtained at 0.66PNN-0.34PT with maximum piezoelectric coefficient d₃₃ of 560 pC/N and large dielectric constant of 28 684. In situ high-energy synchrotron diffraction was employed to determine structural origins of enhanced properties of 0.66PNN-0.34PT. Interestingly, crystal structure of poled 0.66PNN-0.34PT ceramic is determined to be single monoclinic phase. Furthermore, both its lattice parameters and volume variation present butterfly shape under electric field. It is demonstrated that macroscopic strain of 0.66PNN-0.34PT stems mainly from intrinsic structure. The present study provides evidence for the relationship between microstructure and macroscopic properties, which is beneficial to the design of new materials with piezoelectric properties.